@article {JRN55184, title = {Herbivory Effects on Ephedra spp. in the Chihuahuan Desert}, journal = {Open Journal of Ecology}, volume = {10}, year = {2020}, month = { February 2020}, pages = { 37-44 }, abstract = {

Two species of Ephedra: E. trifurca and E. torreyana inhabit shrub and grassland habitats in the northern Chihuahuan Desert. E. torreyana is limited to black grama grasslands where grasses are taller than the shrub. E. torreyana is heavily browsed by vertebrates and E. trifurca is browsed during some years. We established an experiment with cylindrical exclosures that excluded rabbits and rodents, rabbits but accessible to rodents, for comparison with E. torreyana plants available to all herbivores. Plants accessible to all vertebrate herbivores were significantly smaller with shorter stem lengths than plants in exclosures. We concluded that E. torreyana in black grama grassland are largely hidden from vertebrate herbivores and that intense herbivory reflects the degraded state of the study site which makes the E. torreyana evergreen shrubs apparent to vertebrates.

}, keywords = {Desert Cottontail Rabbits (Sylvilagus auduboni), desertification, Ephedra torreyana, Ephedra trifurca, Exclosures, Jackrabbits (Lepus californicus)}, doi = {10.4236/oje.2020.102003}, url = {files/bibliography/20-007.pdf}, author = {Walter G. Whitford and Yosef Steinberger} } @book {JRN55181, title = {Exploring a Desert Experiences of an Ecologist/Naturalist in a New Mexico Desert}, year = {2017}, pages = {189}, abstract = {

The book focuses on the ecology of the northern Chihuahuan Desert with chapters on geomorphology, landscapes, climate, vegetation,(special chapters on Creosotebush and Mesquite) mammals, reptiles, ephemeral aquatic systems, ants, termites, insects on plants, ground dwelling arthropods, and soil fauna. Descriptions of studies and field experiments are provided to show how the information was obtained.

}, keywords = {ants, climate, creosotebush, ecology, ephemeral aquatic systems, geomorphology, ground dwelling arthropods, insects on plants, landscapes, mammals, mesquite, northern Chihuahuan Desert, reptiles, soil fauna., termites, vegetation}, url = {files/bibliography/17-Whitford_Exploring-a-Desert.pdf}, author = {Walter G. Whitford} } @article {49914, title = {Do long-lived ants affect soil microbial communities?}, journal = {Biology and Fertility of Soils}, volume = {48}, year = {2012}, month = {01/15/2012}, pages = {227-233}, chapter = {227}, abstract = {

This study was designed to test the hypothesis that desert ant species that build nests that remain viable at a particular point in space for more than a decade produce soil conditions that enhance microbial biomass and functional diversity. We studied the effects of a seed-harvester ant, Pogonomyrmex rugosus, and two generalist ant species, Aphaeonogaster cockerelli and Myrmecocystus depilis, on soil microbial communities. Microbial biomass was higher in P. rugosus-modified soils than in reference soils when soil water content was higher than 3\%. Microbial biomass was either higher in reference soils or exhibited no difference in reference soils and nest-modified soils of A. cockerelli and M. depilis. There were differences in microbial functional diversity and microbial community level physiological profiles (MicroResp method) between ant-nest-modified and reference soils of the three ant species on some sampling dates. Temporal pattenrs of soil microbial communities associated with the ant species resulted from differences in soil moisture, density, and species composition of the annual plant c0ommunities associated with the ant nests and in reference areas. Differences in annual plant communities associated with ant nests and surrounding areas resulted in different chemical inputs into the soil organic-matter pools. This study shows that generalizations about the effects of long-lived ant nests on soil biota in arid regions must consider feeding behaviors of the ant species and temporal patterns of rainfall.

}, keywords = {ant, aphaenogaster cockerelli, Climate-Community-level physiological profile, CLPP, functional diversity, honeypot ant, microbial biomass, MicroResp method, Myrmecocystus debilis, Pogonomyrmex rugosus}, doi = {10.1007/s00374-011-0619-4}, url = {/files/bibliography/12-014.pdf}, author = {Walter G. Whitford and O. Ginzburg and Berg, Naama and Yosef Steinberger} } @article {49913, title = {Effects of seasonal grazing, drought, fire, and carbon enrichment on soil icroarthropods in a desert grassland}, journal = {Journal of Arid Environments}, volume = {83}, year = {2012}, month = {06/01/2012}, pages = {10-14}, chapter = {10}, abstract = {

This study was designed to test hypotheses about the combined effects of short-term, seasonal grazing with seasonal drought, fire, and carbon enrichment on soil microarthropod communities in a Chihuahuan Desert grassland. The study was conducted in eighteen 0.5 ha plots following three consecutive years of treatment: six plots intensively grazed in summer, six in winter, and six not grazed. There was no difference in perennial grass cover on the summer-grazed and winter-grazed plots. Intensive seasonal grazing had no effect on the abundance and community composition of soil microarthropods. Within each plot there were six subplots: summer rain-out, winter rain-out, burned, glucose amendment, rainout control and burn-glucose control. Fire and carbon enrichment had no significant effect on soil microarthropod abundance or community composition. The average number of microarthropods ranged from 8915 {\textpm} 1422 m-2 in the ungrazed, unburned plots to 7175 {\textpm} 1232 m-2 in the winter-grazed, unburned plots. Microarthropod densities in the glucose-amended plots were 8917 {\textpm} 4902 m-2 in the winter-grazed plots and 10,731 {\textpm} 863 m-2 in the glucose-amended, summer-grazed subplots. The prostigamatid mite, Tydeus sp., was the most abundant microarthropod taxon in all treatment plots. {\textcopyright} 2012 Elsevier Ltd. All rights reserved

}, keywords = {carbon enrichment, cattle, drought, fire, perennial grass cover, prostigmatid mite, rain-out shelter, soil microarthropods}, doi = {10.1016/j.jaridenv.2012.03.021}, url = {/files/bibliography/12-017.pdf}, author = {Walter G. Whitford and Yosef Steinberger} } @article {50002, title = {Effects of simulated storm sizes and nitrogen on three Chihuahuan Desert perennial herbs and a grass}, journal = {Journal of Arid Environments}, volume = {75}, year = {2011}, month = {09/2011}, pages = {861-864}, chapter = {861}, abstract = {Establishment and growth of three perennial herbs and a small tussock grass were studied in an experiment that provided simulated rainfall of 6 mm week_1 or 25 mm once per month and nitrogen fertilization in combination with the different simulated rainfall regimes. Wild onion, Allium macropetalum, failed to establish in plots receiving 25 mm month_1 simulated rainfall. The perennial composite, Bahia absinthifolia, occurred at higher densities in plots that were not irrigated but there were no differences in biomass in any of the irrigation or fertilization treatments. Desert holly, Perezia nana, failed to establish in nitrogen fertilized plots and developed higher abundance and biomass in plots receiving 25 mm month_1. Nitrogen fertilization had either no effect or an adverse effect on the perennial herbs. The tussock grass, Dasychloa pulchella exhibited highest abundance and biomass with 6 mm week_1 added water plus nitrogen. Since global climate change will affect both rain storm frequency and size and atmospheric nitrogen deposition, the results of this study are applicable to understanding vegetation responses climate change.}, keywords = {abundance, biomass, fertilization, irrigation}, doi = {10.1016/j.jaridenv.2011.03.007}, url = {/files/bibliography/11-010.pdf}, author = {Walter G. Whitford and Yosef Steinberger} } @inbook {50065, title = {Herbivore-plant interactions and desertification in arid lands}, booktitle = {All Flesh is Grass}, series = {Cellular Origin, Life in Extreme Habitats and Astrobiology}, number = {16}, year = {2010}, pages = {239-256}, publisher = {Springer-Verlas}, organization = {Springer-Verlas}, abstract = {Arid lands around the world have experienced or are currently experiencing degradation that is known as desertification. Animal-plant interactions that have an effect on desertification are among the most important function of animals in arid ecosystems. Desertification has been defined as land degradation in arid and semiarid areas that is the result of various factors, including climate variation and human activities. The interactions between animals and plants affect desertification arid environments in a number of ways. These interactions may exacerbate desertification processes or contribute to the stability of desertified ecosystems. Some animal-plant interactions are direct, e.g., herbivory, while others are indirect, e.g., seed dispersal and soil modification. Animal-plant interactions that contribute to changes in the structure of plant communities or the spread of alien plant species may enhance some degradation processes such as soil erosion or contribute to soil stability and resistance to degradation.}, keywords = {herbivory, plant-animal interactions}, url = {/files/bibliography/10-037.pdf}, author = {Walter G. Whitford and Yosef Steinberger} } @article {50064, title = {Pack rats (Neotoma spp.): Keystone ecological engineers?}, journal = {Journal of Arid Environments}, volume = {74}, year = {2010}, note = {//NMSU,USDA//LTER V//entered 07/23/2010; pdf available}, month = {2010}, pages = {1450-1455}, chapter = {1450}, abstract = {

The potential role of two species of pack rats (Neotoma albigula) and Neotoma micropus) as keystone ecological engineers was examined by estimating the species diversity of invertebrates living in the nest middens, and nitrogen mineralization rates in soils associated with the middens. Although pack-rat middens in tarbush (Flourensia cernua) shrublands were smaller than those in creosotebush (Larrea tridentata) shrublands, they housed a higher abundance and diversity of arthropods. The Neotoma spp. middens were an important microhabitat for crickets (Gryllus sp.), wolf spiders (Lycosa spp.), and lycid beetle larvae (Lycidae) in all of the shrub habitats. There were five arthropod taxa that occupied all middens in the creosotebush shrubland, and 12 arthropod taxa that occupied all middens in the tarbush shrubland. Soils associated with pack-rat middens had significantly higher soil organic-matter content than reference soils. Nitrogen mineralization was significantly higher in soils associated with pack-rat middens than in reference soils. Neotoma spp. create habitats with moderate microclimates that are essential for several invertebrates, thus contributing to maintenance of biodiversity. The effects of middens on soil organic matter and nitrogen mineralization create nutrient-rich patches. Neotoma spp. affect biodiversity and critical ecosystem processes, thus supporting the designation of keystone ecological engineers. {\textcopyright} 2010 Published by Elsevier Ltd.

}, keywords = {habitat, mineralization, species diversity, stick nest, woodrat}, doi = {10.1016/j.jaridenv.2010.05.025}, url = {/files/bibliography/10-050.pdf}, author = {Walter G. Whitford and Yosef Steinberger} } @article {50153, title = {Harvester ants (Hymenoptera: Formicidae) discriminate among artificial seeds with different protein contents}, journal = {Sociobiology}, volume = {53}, number = {2B}, year = {2009}, month = {03/2009}, pages = {549-558}, chapter = {549}, abstract = {

Workers of colonies of the western harvester ant, Pogonomyrmex occidentalis, were recruited to patches of artificial seed of the same caloric value but different protein content. Rates of forager returns with artificial seeds containing five percent protein were nearly twice those of zero percent protein. Differences in foraging rates on artificial seeds of ten and twenty percent protein compared to foraging rates on zero percent protein seeds were not different from the comparison of foraging rates on five percent and zero percent protein seeds. There were no differences in foraging rates on zero percent protein seeds, 0.5 percent and one percent protein seeds. P. occidentalis presented with patches containing equal amounts of zero, five, ten, and twenty percent protein seeds returned equal amounts of each protein content seed type to the colonies. When presented with high quality seed patches in the same location for four successive days, the rates of forager returns increased over time. When seed patch locations were switched, P. occidentalis\&$\#$39; rate of return of zero protein content seeds was the same as for the five percent protein seeds at that location the previous day. Seeds with protein content between one and two percent represent a threshold for seed quality that affects the foraging rate of P. occidentalis workers.

}, keywords = {food choices, Harvester ants, journal, Pogonomyrmex occidentalis, protein}, url = {/files/bibliography/09-009.pdf}, author = {Walter G. Whitford and Yosef Steinberger} } @article {50302, title = {Effects of three species of Chihuahuan Desert ants on annual plants and soil properties}, journal = {Journal of Arid Environments}, volume = {72}, year = {2008}, month = {04/2008}, pages = {392-400}, chapter = {392}, abstract = {We tested the hypothesis that ant species, which occupy the same nest for a decade or longer, would modify nest soils by increasing soil nutrients and microorganisms resulting in increased biomass, density, cover and species richness of annual plants. We measured soil properties and annual plants on nest soils of three species of Chihuahuan Desert ants (Pogonomyrmex rugosus--seed harvester, Aphaenogaster cockerelli--generalist forager, and Myrmecocystus depilis--liquid collector-insect scavenger) in comparison to paired reference soils at several locations. There were no differences in nest and reference total soil nitrogen of M. depilis and of P. rugosus on three catena soils. Total soil nitrogen of nest-modified soils was higher than of reference soils of A. cockerelli and P. rugosus in a desert grassland site. Soil microbial biomass and respiration were not significantly different among ant species at most locations with the exception of P. rugosus at the base of the catena. Annual plant biomass was higher on M. depilis and A. cockerelli nest soils than on the reference soils. Annual plant biomass was higher on P. rugosus nest soils than on reference soils at the base of the catena and in the grassland but not at the mid-slope and top of the catena. The effects of long-lived ant colony nests on soil properties and vegetation vary in time and space but are independent of the feeding behavior of the ant species.}, keywords = {aphaenogaster cockerelli, Generalist foragers, Honey-pot ants, microbial biomass, myrmecocystus depilis, Persistent nests, Pogonomyrmex rugosus, soil respiration}, doi = {doi:10.1016/j.jaridenv.2007.07.012}, url = {/files/bibliography/08-055.pdf}, author = {Walter G. Whitford and Barness, G. and Yosef Steinberger} } @article {50400, title = {Seed harvester ants (Polonomyrmex rugosus) as "pulse" predators}, journal = {Journal of Arid Enviornments}, volume = {70}, year = {2007}, month = {03/2007}, pages = {549-552}, abstract = {Seed harvesting ants, Pogonomyrmex rugosus, collected grass cicadas at a high rate (\>5 min-1 taken into the nest) at one location where cicada emergence exceeded 3m-2. Dry conditions in the winter-spring resulted in no annual plants in the northern Chihuahuan Desert. P. rugosus colonies were inactive in areas where grass cicada emergence was less than 1 m-2. P. rugosus initiate intense predatory activity in response to pulse of large numbers of prey. This study demonstrates that predatory behavior of seed harvesting ants is not limited to incidental encounters with prey during seed harvesting activities. Pulse predation demonstrates the importance of protein to seed harvester ant colonies.}, keywords = {Beameria vanosa, forage ecology, grass cicadas}, doi = {10.1016/j.jaridenv.2007.01.005}, url = {/files/bibliography/07-015.pdf}, author = {Walter G. Whitford and E. Jackson} } @inbook {50522, title = {Chihuahuan Desert Fauna: Effects on Ecosystem Properties and Processes}, booktitle = {Structure and Function of a Chihuahuan Desert Ecosystem: The Jornada Basin Long-Term Ecological Research Site}, year = {2006}, month = {July 1, 2006}, pages = {247-265}, publisher = {Oxford University Press}, organization = {Oxford University Press}, chapter = {12}, address = {New York, NY}, abstract = {This chapter addresses the direct and indirect effects of animals on ecosystem processes and/or their effects on ecosystem properties. This has been the primary focus of animal studies on the Jornada Experimental Range (JER) and the Chihuahuan Desert Rangeland Research Center (CDRRC) during the twentieth century. Early studies dealt with animal species that were thought to reduce the amount of primary production that was available to support livestock. With the establishment of the International Biological Programme (IBP) in the late 1960s and its premise that ecosystems could be modeled based on the energy flow conceptual model, animal studies were designed to measure energy flow through consumer populations. Those studies yielded estimates of consumption of live plant biomass between 1 and 10\% of the annual net primary production. It was concluded that, in most ecosystems, consumers process only a small fraction of the net primary production as live plant material and consumers play important roles in ecosystems as regulators of ecosystem processes and a less important role in energy flow. This hypothesis has been the focus of animal studies in the Jornada Basin for nearly 30 years. Studies of animals as regulators of ecosystem processes led to the expansion of this hypothesis to include the effects of animals on ecosystem properties. Expanding the spatial scale of studies from the patch to the watershed and landscape engendered hypotheses that animals have an effect on processes at those scales because of animal activities that affect redistribution of soil and organic matter.}, keywords = {Chihuahuan Desert, Jornada Basin, LTER, synthesis book}, url = {/files/bibliography/06-063.pdf}, author = {Walter G. Whitford and Brandon T Bestelmeyer}, editor = {Kris Havstad and L. Huenneke and W. H. Schlesinger} } @article {50836, title = {The functional significance of cemented nest caps of the harvester ant, Pogonomyrmex maricopa}, journal = {Journal of Arid Environments}, volume = {53}, year = {2003}, note = {//USDA//LTER IV//}, month = {2003}, pages = {281-284}, abstract = {

Harvester ants, Pogonomyrmex maricopa, construct cemented caps on the sand mound nests in a fine sand dune area. The caps are approximately 60\% calcium carbonate that is transported from the underlying calcium carbonate layers. The caps protect the nest structure from being eroded away during high-wind periods. Partial erosion of the cemented caps adds calcium carbonate to the sand dune soils.

}, keywords = {ant nest, soil effects, ant, calcium carbonate, ant, harvester ant, ant, Pogonomyrmex, article, articles, calcium carbonate, ants, journal, journals, wind erosion, ants}, doi = {10.1006/jare.2002.1039}, url = {files/bibliography/JRN00399.pdf}, author = {Walter G. Whitford} } @inbook {50954, title = {Ants}, booktitle = {Encyclopedia of Soil Science}, year = {2002}, month = {July 8, 2002}, pages = {76-79}, publisher = {Marcel Dekker, Inc.}, organization = {Marcel Dekker, Inc.}, address = {Columbus, OH}, abstract = {Ants are among the most ubiquitous insects on the planet. They occur in all biomes except for the extreme polar regions. In the biomes where ants are abundant, they affect many soil processes that contribute to the creation of patch mosaics that characterize the soils and vegetation of many landscapes. The abundance and diversity of soil-nesting ants varies from as high as 7,000 colonies per hectare in tropical savanna to as few as 3-4 colonies per hectare on some periodically flooded, fine-textured soil, desert landscape units. Soil-nesting ants affect critical ecosystem processes, such as nutrient cycling and water redistribution. Ant nest mounds vary from a few centimeters in height and diameter to less than 1 m in height and less than 2 m diameter. Ant nests consist of underground, branched networks of galleries and chambers. Surficial chambers are connected to lower chambers by vertical galleries with branching lateral galleries. Galleries and chambers vary in size and number depending on the species of ant. For example, Lasius neoniger, an abundant ant species in temperate North America, constructs tubular galleries of 1.5-5.0 mm in diameter and chambers of 10-20 mm diameter and 30-50 mm in length. The volume of L. neoniger nests range from 20-250 cm (to the third power) and are confined to the upper 70 cm of soil (3). Other species construct nests to depths ranging from 50 cm to greater than several meters, depending on species-specific behavior, soil type, and landscape position. Soil profile mixing, texture, physical and chemical property modification of mound soils, soil macroporosity, and geomorphological attributes of ant nest mounds vary with species-specific colony longevity, body size, and numbers of workers of a colony, soil type, and landscape position. The pedturbation effects of ants are, therefore, dependent on the species composition of the ant community, geomorphic history, soil properties, and topographic position of a landscape unit. Because most studies of the effects of ants on soils have focused on one or two species, a comprehensive analysis of the combined effects of all ant species on the soils of an ecosystem cannot be made.}, url = {/files/bibliography/02-084.pdf}, author = {Walter G. Whitford}, editor = {R. (ed.) Lal} } @book {50953, title = {Ecology of Desert Systems}, year = {2002}, month = {March 1, 2002}, publisher = {Academic Press}, organization = {Academic Press}, address = {New York, NY}, abstract = {

Conventional wisdom considers deserts stark, harsh regions that support few living things. Most people also believe that water alone makes the desert bloom. Ecology of Desert Systems challenges these conventional views. This volume explores a broad range of topics of interest to ecosystem, population, community, and physiological ecologists. Climate, weather patterns, geomorphology, and wind and water processes are examined as variables that affect the distribution of biota through fundamental ecosystem processes. Descriptions of morphological, behavioral, and physiological adaptations of desert biota illuminate, through the lens of patch dynamics, principles for understanding observed patterns of primary production, nutrient cycling, and the effects of consumers. Desertification and the techniques for monitoring and quantifying it is examined within the framework of desert ecosystem patterns and processes. With 12 chapters and over 70 figures and tables, Ecology of Desert Systems is the only book that covers the entire desert ecosystem at this academic level. Readers are provided with an excellent reference framework for their desert ecology research.

}, keywords = {community, desert systems, ecology, physiological ecology, population, research}, url = {https://www.elsevier.com/books/ecology-of-desert-systems/whitford/978-0-12-815055-9}, author = {Walter G. Whitford}, editor = {Walter G. Whitford} } @article {51061, title = {Establishment and effects of establishment of creosotebush, Larrea tridentata, on a Chihuahuan Desert watershed}, journal = {Journal of Arid Environments}, volume = {47}, number = {1}, year = {2001}, month = {January 1, 2001}, pages = {1-10}, abstract = {Creosotebush (Larrea tridentata) seedlings were planted in plots that were irrigated, plots that were irrigated and fertilized with ammonium nitrate, and plots that were not amended in three plant communities on a Chihuahuan Desert watershed: ungrazed black grama (Bouteloua eriopoda) grassland, creosotebush shrubland, and overgrazed grassland. No seedlings were planted in one-half of the area of each plot. No seedlings survived in the black grama grassland or the creosotebush shrubland 2 years after planting. Growth of established creosotebush shrubs was highest in plots with the lowest grass cover. Fifteen years after the seedlings were planted in the overgrazed grassland, the area under the shrubs was nearly devoid of perennial grasses and forbs. The aggregate stability of the soils under the established creosotebush shrubs was significantly lower than the soils in the unplanted split-half of the plots. Electrical conductivity, calcium, and nitrate were significantly lower in soils under shrubs than soils in the unplanted split-half of the plots. There were also significant reductions in densities of annual plants growing under the shrubs than in the unplanted split-half of the plots. Successful establishment of creosotebush in desert grasslands is dependent upon the presence of large patches of soil with no perennial plant cover. Intense grazing by domestic livestock creates microsites and landscape characteristics favorable for seed dispersal, germination and establishment of creosotebush. Soil changes resulting from shrub establishment reduce the probability of reestablishing perennial grasses in creosotebush-dominated shrubland.}, keywords = {Chihuahuan Desert, creosotebush, effects, establishment, Larrea tridentata}, url = {/files/bibliography/01-057.pdf}, author = {Walter G. Whitford and R. M. Nielson and A.G. de Soyza} } @inbook {51060, title = {Invertebrates: Their effects on the properties and processes of desert ecosystems}, booktitle = {Ecology of Desert Environments}, year = {2001}, month = {January 1, 2001}, pages = {333-356}, publisher = {Scientific Publishers}, organization = {Scientific Publishers}, address = {Jodhpur, India}, abstract = {This book chapter summarizes the role of invertebrate animals as regulators of ecosystem processes and their effects on the properties of ecosystem properties in arid lands. Several groups of invertebrates are key players in decomposition and nutrient cycling processes. Soil nematodes that feed on bacteria and fungi regulate the population growth of these soil microbes, thereby affecting the rates of decomposition, nitrogen mineralization, and rates of cycling of other nutrients. Soil nematode populations are regulated by predation by several taxa of mites. Fungal feeding mites are also directly involved in mineralization processes and are key invertebrates in nutrient cycling because they maintain activity in dry soils. Soil bacteria, protozoans and nematodes cease activity when soil water potentials fall below the wilting point for agronomic plants. The most important arid soil animals are termites. Termites supplant earthworms in arid soils as the animals that process dead plant material. Termites process between 30\% and 70\% of dead plants, depending upon the species, and also process much of the dung of large herbivores. Because of the efficiency of the microflora and microfauna in the hind gut of termites, most of the plant material they consume is converted to carbon dioxide and water. There is a strong negative correlation between termite abundance and soil organic matter in Chihuahuan Desert rangelands and African rangelands. Termites are primarily responsible for the low organic carbon content of desert rangeland soils.Pedogenesis (soil formation) in arid environments is significantly affected by invertebrate animals. Desert snails consume large quantities of soil algae, grind surfaces of exposed limestone and grind soil crusts. Their fecal material is chemically and physically different from the materials that are ingested, thereby contributing to soil formation. Burrowing and nest building by ants, isopods, and burrowing spiders results in soil turnover with subsoil deposited on the surface. This activity is functionally similar to plowing but over geological time periods. Termites build above-ground nests and foraging galleries and sheeting from subsurface soils, thereby contributing to soil turnover and pedogenesis.In arid rangeland soils invertebrates directly affect hydrological properties of soil by the production of macropores. Macropores are continuous tubes or spaces (voids) in the soil with diameters larger than spaces in which capillary water movement occurs. During rains, water moves down macropores by bulk flow. Bulk flow is rapid and quickly wets deep soil layers around macropores. Arthropods in order of relative importance for the production of macropores in arid rangelands are: termites, ants, isopods, burrowing spiders, cicadas, and beetles. Emperical measurements of the effects of subterranean termites on hydrology have shown that infiltration rates on plots with termites are more than double those on plots with termites eliminated.Several species of ants and termites have been documented to be responsible for producing fertile patches in arid rangelands and thereby affecting plant production and plant species composition of the patches. Insects not only affect plant production by changing soil fertility, some species of Cerambicid beetles and Bostrichid beetles stimulate productivity of mesquite (Prosopis glandulosa) by girdling or boring into stems to provide safe sites for larval development. Mesquite exhibits compensatory growth by producing a number of stem leaders at nodes below the girdle or bore entrance. The pruning of shrubs by girdling and boring insects exacerbates the problem of shrublands that resist control efforts and remain in a degraded state.}, keywords = {arid lands, decomposition, ecosystem processes, invertebrates, macropores, properties}, url = {/files/bibliography/01-055.pdf}, author = {Walter G. Whitford}, editor = {Prakash, I.} } @article {51198, title = {Ants as indicators of exposure to environmental stressors in North American desert grasslands}, journal = {Environmental Monitoring and Assessment}, volume = {54}, year = {1999}, month = {1999}, pages = {143-171}, abstract = {

The relative abundance of ant species was measured by pit-fall trapping at 44 sites in southern New Mexico and southeastern Arizona, U.S.A.. Sites were selected for study based on documentation of a history of disturbance or protection from disturbance, exposure to varying intensities of livestock grazing, dominance by an exotic species of plant and vegetation change resulting from disturbance or restoration efforts. Ant community composition, relative abundance of species, and species richness were the same on disturbed and undistrubed sites. None of the metrics based on hypothesized responses of ants to disturbance clearly distinguished between disturbed and undisturbed sites. Ant communities on sites where restoration efforts have resulted in distinct differences in vegetative cover and composition were similar to the ant communities on degraded unrehabilitated sites on the same soil type. Ant communities in riparian cottonwood gallery forests in Arizona and New Mexico were similaar but differed from the assemblages in exotic salt cedar and native ash riparian woodlands. Ant species exhibited remarkable resistance to human-induced disturbance in these rangeland areas. In grasslands dominated by the South African grass, Eragrostis lehmanniana Nees, large seed harvesting ants, Pogonomyrmex spp., were greatly reduced in abundance compared to native grasslands. Other ants metrics were not different in E. lehmanniana grasslands and native grasslands. We conclude that ants cannot be used as indicators of exposure to stress, ecosystem health or of rehabilitation success on rangeland ecosystems. Ants are also not useful indicators of faunal biodiversity in rangeland ecosystems.

}, keywords = {environmental stressors, exposure indicators}, doi = {10.1023/A:1005858918860}, url = {/files/bibliography/535.pdf}, author = {Walter G. Whitford and Justin Van Zee and M. S. Nash and W. E. Smith and Jeffrey E. Herrick} } @article {51201, title = {Biopedturbation by mammals in deserts: A review}, journal = {Journal of Arid Environments}, volume = {41}, number = {2}, year = {1999}, month = {February 1, 1999}, pages = {203-230}, abstract = {

Disturbance-caused patchiness is important for development and maintenance of spatial and temporal heterogeneity in ecosystems. Mammals are important agents of biopedturbation (soil disturbance by organisms) which is a major source of patchiness in arid ecosystems. The contribution of soil disturbance by mammals to heterogeneity is a function of the size and longevity of the soil disturbance. Foraging pits produced by a variety of mammals are relatively short-lived features that trap plant litter and seeds that are rapidly buried. These form nutrient-rich germination sites. High water infiltration rates, a low bulk density rooting environment, and frequently increased soil nutrient content (especially mounds of central-place foragers and larder-hoarders) characterize warren complexes. Productivity tends to be higher on these mounds and the vegetation tends to differ in composition and richness from the surrounding areas. Soil ejected from fossorial mammal burrow systems is generally of low bulk density, erodes readily, and varies greatly with respect to concentration of nutrients and organic matter depending upon the species and landscape in which the species lives. The variability in soil properties of fossorial burrow system ejecta mounds precludes generalizations about the effects of these disturbances on vegetation. Long-lived features such as Mima-like mounds and heuweltjies are nutrient-rich features that support high productivity and a distinct floral assemblage. There is a significant relationship between longevity of mammal soil disturbance and size of the disturbance: longevity in years=9.33 Area0.735. The data suggest that pedturbation by mammals can be an important force in pedogenesis, in structuring landscapes, and in maintaining heterogeneity in ecosystems. Data on mammalian pedturbation is based on scattered autecological studies. There is a need for long-term studies that focus on biopedturbation (soil disturbance by invertebrates and vertebrates) as a process at scales from the patch to the landscape.

}, keywords = {Biopedturbation, burrows, deserts, disturbance, fossorial rodents, patch dynamics, small mammals, soil properties}, doi = {10.1006/jare.1998.0482}, url = {/files/bibliography/696.pdf}, author = {Walter G. Whitford and F. R. Kay} } @article {51199, title = {Effects of habitat characteristics on the abundance and activity of subterranean termites in arid southeastern New Mexico (Isoptera)}, journal = {Sociobiology}, volume = {34}, number = {3}, year = {1999}, month = {December 1, 1999}, pages = {493-504}, abstract = {

Amitermes wheeleri was the most abundant termite species in most of the habitats. Gnathamitermes tubiformans was the most abundant subterranean termite species in habitats dominated by creosotebush, Larrea tridentata. Subterranean termite abundance measured by numbers of termites extracted from baits, mass of paper removed from baits, proportion of dung pats attacked, and quantities of surface foraging galleries all indicated that subterranean termites were most abundant in mesquite (Prosopis glandulosa) dune and creosotebush habitats and least abundant in grassland and shinnery oak (Quercus harvardii) habitats. Subterranean termite abundance was not affected by soil stability but by the dominant vegetation. Subterranean termites consumed more than 80\% of the creosotebush leaf litter from litter bags between August and December. There was no evidence that termites consumed shinnery oak leaves or grass stems and leaves.

}, url = {/files/bibliography/697.pdf}, author = {Walter G. Whitford} } @article {51196, title = {Effects of repeated drought on soil microarthropod communities in the northern Chihuahuan Desert}, journal = {Biology and Fertility of Soils}, volume = {28}, number = {2}, year = {1999}, month = {April 1, 1999}, pages = {117-120}, abstract = {

Soil microarthropods were sampled in plots centered on creosotebushes (Larrea tridentata) and in plots centered on mesquite (Prosopis glandulosa) coppice dunes. Nine plots in each area were covered by rain-out shelters with greenhouse plastic roofs which excluded natural rainfall and nine plots received natural rainfall. There were differences in the abundance of several mite taxa in soils from the mesquite coppice dune plots. Some taxa (Stigmaeidae, Nanorchestidae and Entomobryidae) occurred in significantly lower numbers in the soils of the drought plots. Other taxa (Tarsonemidae and Cunaxidae) were more abundant in the drought plots in the mesquite coppice dunes. There were no significant differences in the abundance of any of the dominant taxa of soil microarthropods in the drought and control plots centered on creosotebush. In the creosotebush habitat, there were significantly fewer Prostigmata in the plots exposed to drought. In an area with both creosotebush and mesquire, there were no significant differences in microarthropod population responses to drought and in recovery from drought. The differences in responses of soil microarthropods to drought in creosotebush and mesquite habitats are attributed to the differences in soil stability, litter accumulations, and microclimate associated with the shrubs.

}, keywords = {community, soil microarthropod, drought, soil microarthropod, journal, journals, soil, microarthropod}, doi = {10.1007/s003740050471}, url = {/files/bibliography/99-002.pdf}, author = {Walter G. Whitford and Sobhy, H. M.} } @article {51200, title = {Seasonal and diurnal activity patterns in ant communities in a vegetation transition region of southeastern New Mexico (Hymenoptera: formicidae)}, journal = {Sociobiology}, volume = {34}, number = {3}, year = {1999}, month = {December 1, 1999}, pages = {477-491}, abstract = {

The densities of active ant colonies were estimated in three habitats: creosotebush shrubland, grassland, and shinnery-oak mesquite dunes. Diurnal foraging patterns were studied at bait boards. Species richness of ant communities in this transitional region (8-12 species) was considerably lower than Chihuahuan Desert ant communities in an area with lower annual average rainfall. The numerically dominant species was Forelius pruinosus. Crematogaster spp. Was subdominant in all of the habitats and exhibited relatively constant activity throughout the growing season. Harvers ants, Pogonomyrmex spp. Exhibited different seasonal activity patterns in the three habitats. One species, Trachymyrmex septentrionalis, was not recorded until October, when its nests were conspicuous with discarded leaf fragments around the entrances. Several species of ants feeding at bait board extended their foraging times in comparison to colonies of the same species too distant from the bait boards for foragers to reach the baits. Only one species (Pogonomyrmex apache) exhibited a high-tolerance foraging behavior by initiating foraging at the bait boards after soil surface temperatures exceeded 40{\textordmasculine}C and other species had ceased foraging. Foraging activity of most species continued throughout the day when cloud cover reduced soil surface temperatures to 40{\textordmasculine}C during midday.

}, keywords = {ant communities, diurnal activity, seasonal activity, vegetation transition}, url = {/files/bibliography/695.pdf}, author = {Walter G. Whitford} } @article {51197, title = {Using resistance and resilience measurements for {\textquoteleft}fitness{\textquoteright} tests in ecosystem health}, journal = {Journal of Environmental Management}, volume = {57}, number = {1}, year = {1999}, month = {September 1, 199}, pages = {21-29}, abstract = {

The resistance and resilience of perennial grasses and a small shrub to a natural disturbance (drought) were measured on stress gradients that were produced by domestic livestock in desert grassland ecosystems in the northern Chihuahuan Desert of New Mexico, USA. Both survivorship of grasses and a sub-shrub (Gutierrezia sarothrae) during a drought (a measure of resistance) and re-establishment of plant cover following a drought (a measure of resilience) were reduced in the intensely stressed ecosystems in comparison to the lightly stressed ecosystems. The compromise of the resistance and resilience characteristics of an ecosystem can be used as a {\guillemotleft}fitness{\guillemotright} test for the health of ecosystems. Fitness tests can provide early warning of ecosystem degeneration and allow intervention to reduce or eliminate anthropogenic stress on the ecosystems.

}, keywords = {disturbance, ecosystem health, fitness test, grazing, resilience, resistance, stress, survivorship}, doi = {10.1006/jema.1999.0287}, url = {/files/bibliography/534.pdf}, author = {Walter G. Whitford and D. J. Rapport and A.G. de Soyza} } @article {51258, title = {Contribution of pits dug by goannas (Varanus gouldii) to the dynamics of banded mulga landscapes in eastern Australia}, journal = {Journal of Arid Environments}, volume = {40}, number = {4}, year = {1998}, month = {December 1, 1998}, pages = {453-457}, abstract = {

The densities of pits made by goannas Varanus gouldii were estimated in the three distinct zones of banded mulga landscapes (erosion slope, interception zone, and mulga grove) in paddocks of a grazing study in northwestern New South Wales, Australia. In lightly and moderately grazed paddocks, soil pits were significantly more abundant in the interception zones (M = 119{\textbullet}7m to the -2 degree) than in the groves and erosion slopes (M = 16{\textbullet}m to the -2 degree). In the overgrazed paddock, there were no differences in densities of pits in any of the zones. In the groves and erosion slopes, approximately 70-80\% of the pits contained litter, seeds, and fruits. However, on the erosion slopes, less than 20\% of the pits contained litter and seeds. The data support the hypothesis that soil disturbance by Varanus lizards produces a positive feedback mechanism for the viability of the interception zone and the functioning of banded vegetation landscapes.

}, keywords = {Australia, banded vegetation, goannas, grazing, landscapes, lizard, pits, seeds}, doi = {10.1006/jare.1998.0464}, url = {/files/bibliography/645.pdf}, author = {Walter G. Whitford} } @inbook {51257, title = {The desert grasslands}, booktitle = {Ecosystem Health}, year = {1998}, month = {1998}, pages = {313-323}, publisher = {Blackwell Science, Inc.}, organization = {Blackwell Science, Inc.}, chapter = {20}, address = {Malden, MA}, abstract = {

The desert grasslands are widely distributed in North America, occupying much of southeastern Arizona, the southern half of New Mexico, and west Texas in the United States and extending southward through 13 states in Mexico, from Sonora to Puebla. They represent more than 500,000 km2 of basin and valley lands that skirt the hills and mountain ranges of southwestern North America (McClaran 1995). The entire geographic range of the desert grasslands has seen a rapid decline in grass cover and an increase in cover by woody shrubs, especially mesquite (Prosopis spp.) and creosotebush (Larrea tridentata). Traditionally, the desert grasslands have supported extensive stands of perennial bunch grasses, known colloquially as the grama grasses, which reproduce primarily by stolons. Other, smaller bunch grasses occupied habitat patches such as infrequently inundated swales that support a cover of tabosa grass, Hilaria mutica.

}, url = {/files/bibliography/639.pdf}, author = {Walter G. Whitford}, editor = {D. J. Rapport and Costanza, R. and Epstein, P.R. and C. Gaudet and Levins, R.} } @inbook {51256, title = {Validation of indicators}, booktitle = {Ecosystem Health}, year = {1998}, month = {1998}, pages = {205-209}, publisher = {Blackwell Science, Inc.}, organization = {Blackwell Science, Inc.}, chapter = {12}, address = {Malden, MA}, abstract = {

Assessing the health of any ecosystem requires the measurement of a number of indicators. For an assessment of ecosystem health to have real value, it must not only address status, but also evaluate the risk of that status changing to a less healthy state. Although numerous indicators of ecosystem health have been proposed (Rapport et al 1985; National Research Council 1993), few have been tested to date. Such testing must incorporate evaluation of the indicator{\textquoteright}s sensitivity so as to provide unambiguous and reliable values for the assessment of ecosystem status. Indicator sensitivity must also be known so as to enable an evaluation of the risk of change in the health status of the ecosystem.

}, url = {/files/bibliography/640.pdf}, author = {Walter G. Whitford}, editor = {D. J. Rapport and Costanza, R. and Epstein, P.R. and C. Gaudet and Levins, R.} } @article {51255, title = {Vegetation, soil, and animal indicators of rangeland health}, journal = {Environmental Monitoring Assessment}, volume = {51}, year = {1998}, month = {June 1, 1998}, pages = {179-200}, abstract = {

We studied indicators of rangeland health on benchmark sites with long, well documented records of protection from stress by domestic livestock or histories of environmental stress and vegetation change. We measured ecosystem properties (metrics) that were clearly linked to ecosystem processes. We focused on conservation of soil and water as key processes in healthy ecosystems, and on maintenance of biodiversity and productivity as important functions of healthy ecosystems. Measurements from which indicators of rangeland health were derived included: sizes of unvegetated patches, cover and species composition of perennial grasses, cover and species composition of shrubs and herbaceous perennials, soil slaking, and abundance and species composition of the bird fauna. Indicators that provided an interpretable range of values over the gradient from irreversibly degraded sites to healthy sites included: bare patch index, cover of long-lived grasses, palatability index, and weighted soil surface stability index. Indicators for which values above a threshold may serve as an indicator of rangeland health include: cover of plant species toxic to livestock, cover of exotic species, and cover of increaser species. Several other indicator metrics were judged not sensitive nor interpretable. Examples of application of rangeland health indicators to evaluate the success of various restoration efforts supported the contention that a suite of indicators are required to assess rangeland health. Bird species diversity and ant species diversity were not related to the status of the sample site and were judged inadequate as indicators of maintenance of biodiversity.

}, doi = {10.1023/A:1005987219356}, url = {/files/bibliography/641.pdf}, author = {Walter G. Whitford and A.G. de Soyza and Justin Van Zee and Jeffrey E. Herrick and Kris Havstad} } @article {51313, title = {Desertification and animal biodiversity in the desert grasslands of North America}, journal = {Journal of Arid Environments}, volume = {37}, year = {1997}, month = {1997}, pages = {709-720}, abstract = {

Studies of breeding birds and small mammals were conducted at a series of sites that form a gradient of severity of desertification. Desert grassland sites represented the least changed landscape units and mesquite coppice dunes represented the most severe degradation, an irreversibly degraded landscape unit. The hypothesis that desertification reduces species diversity was not supported by the data. Species richness and diversities (Shannon-Weaver H') of breeding birds were higher in the desertified areas than in the grassland with one exception. Data from a site dominated by the exotic African grass, Eragrostis lehmanniana, in south-eastern Arizona showed that breeding bird diversity was lower at that site than at a site in the same region that was dominated by native grasses. Species richness, diversity (H'), and abundance of small mammals were also higher in desertified areas than in desert grassland. Most grassland species of birds and mammals persist in the desertified habitats and species that are characteristic of shrublands colonize desertified desert grasslands. This accounts for the increases in species richness. However some species such as the banner-tailed kangaroo rat, Dipodomys spectabilis, are eliminated when grassland degrades to mesquite coppice dune or eroded creosotebush communities. These data suggest that other measures of faunal biodiversity such as keystone species may be better measures of the impact of desertification on animal biodiversity.

}, keywords = {biodiversity, breeding birds, desert grasslands, desertification, exotic species, rodents}, doi = {10.1006/jare.1997.0313}, url = {/files/bibliography/600.pdf}, author = {Walter G. Whitford} } @conference {51312, title = {Desertification and biodiversity}, booktitle = {International Symposium and Workshop Combating Desertification: Connecting Science with Community Action}, year = {1997}, month = {May 12-16, 1997}, pages = {Abstract 44}, address = {Tucson, AZ}, abstract = {

Desertification is widely recognized as causing dramatic and frequently irreversible changes in the composition and cover of vegetation and loss of soil and soil productivity. Conventional wisdom holds that such change should result in equally dramatic changes in faunal biodiversity. Intensive study of breeding birds, winter birds, ant communities, soil microarthropods, small mammals, and ground arthropods failed to provide clear or consistent patterns that could be related to the degree of degradation and/or exposure to chronic anthropogenic stressors. We examine the problem of measurements of faunal biodiversity in rangeland ecosystems. Measurements that include data on keystone species, critical link species, exotic and alien species, and distribution of life forms may provide better assessment opportunities and have the potential for incorporation into monitoring systems. Examples of these data are given for Chihuahuan Desert ecosystems.

}, author = {Walter G. Whitford and P.U. Alkon and W. E. Smith and Justin Van Zee} } @article {51311, title = {Stemflow contribution to the "fertile island" effect in creosotebush, Larrea tridentata}, journal = {Journal of Arid Environments}, volume = {35}, year = {1997}, month = {1997}, pages = {451-457}, abstract = {

Stemflow, throughfall and bulk precipitation were collected on six creosotebushes (Larrea tridentata) during 18 events in the summer rainy season in the northern Chihuahuan Desert. The average stemflow was 16{\textperiodcentered}8 {\textpm} 1{\textperiodcentered}9\%; throughfall averaged 64{\textperiodcentered}7 {\textpm} 3{\textperiodcentered}2\%. The concentration of all ions measured were significantly higher in stemflow than in the bulk precipitation. Total nitrogen, sulfate, and calcium concentrations were more than an order of magnitude higher in the stemflow than in the bulk precipitation. Concentration of ions in the upper 10 cm of soil were generally higher in soils under shrubs than in soils between shrubs. Measured quantities of ions in dry-fall were of sufficient magnitude to account for the increased concentration in stemflow water of most ions. Increases in nitrogen in stemflow water may be due to biological activity of stem crust micro-organisms in addition to dry-fall. Dry-fall that collects on the leaves and stems of this desert shrub may contribute to the {\textquoteleft}fertile island{\textquoteright} effect on the soils under the canopies of creosotebushes.

}, keywords = {bulk precipitation, creosotebush, dryfall, Larrea tridentata, soil fertility, stemflow, throughfall}, doi = {10.1006/jare.1996.0164}, url = {/files/bibliography/602.pdf}, author = {Walter G. Whitford and John P. Anderson and P.M. Rice} } @article {51378, title = {The importance of the biodiversity of soil biota in arid ecosystems}, journal = {Biodiversity and Conservation}, volume = {5}, year = {1996}, month = {1996}, pages = {185-195}, abstract = {

The importance of soil biota in maintaining ecosytem integrity is examined by a review of studies of soil processes and soil biota in arid ecosystems. In decomposition and mineralization processes, there is a temporal succession of microarthropod and nematode species. Tydeid mites are keystone species in the early stages of decomposition. Soil pore neck size variation affects the spatial distribution of soil biota and requires that species differ in size to provide efficient processing of organic matter. In arid ecosystems, the sub-set of soil biota that is active at any point in time is determined by the soil water potential and soil temperature. The structure of soil microarthropod assemblages is similar in several arid regions of the world and abundance and diversity are directly related to quantity of litter accumulations and soil organic matter. The unique life histories and behavioural characteristics of desert soil macrofauna (termites and ants) determine the effects of these organisms on soil properties and soil formation. The soil biota, by affecting the spatial and temporal distribution of essential sesources (water and nutrients), are essential to the maintenance of the ecosystem integrity of arid ecosystems.

}, keywords = {ants, diversity, functional groups, keystone species, microarthropods, nematodes, protozoans, termites}, doi = {DOI: 10.1007/BF00055829}, url = {/files/bibliography/504.pdf}, author = {Walter G. Whitford} } @proceedings {51379, title = {Maintaining soil processes for plant productivity and community dynamics}, volume = {II}, year = {1996}, month = {1996}, pages = {33-37}, abstract = {

Rangeland soil biota affect soil properties and processes that control the availability of water and nutrients that are essential for the maintenance of productivity and vegetation composition. oil processes mediated by soil biota include decomposition, nutrient immobilization and mineralization, storage and release of water and nutrients, nitrogen fixation and denitrification, production of plant growth factors and nutrient uptake by mycorrhizae. oil biotic processes control aggregate creation and maintenance, soil macropore formation, and spatial-temporal patterns of soil organic matter and nutrients.

}, keywords = {community dynamics, plant productivity, soil processes}, author = {Walter G. Whitford and Jeffrey E. Herrick} } @article {51428, title = {Desertification: Implications and limitations of the ecosystem health metaphor}, volume = {I(28)}, year = {1995}, month = {1995}, pages = {273-292}, abstract = {

The semi-arid and arid regions of the world may provide some valuable insights into the applicability of the ecosystem {\textquotedblleft}health{\textquotedblright} and ecosystem {\textquotedblleft}medicine{\textquotedblright} metaphors. These regions provide an example of the applications and limitations of the metaphor because they have experienced and continue to experience degradation and change. Attempts at rehabilitation of degraded areas has proven to be expensive or impossible. Those parameters that are frequently examined to determine the {\textquotedblleft}health{\textquotedblright} of ecosystems may be more robust in ecosystems that are generally considered to be degraded than in those perceived as healthy. Most such areas have suffered loss of productivity as measured by the capacity to support livestock and human inhabitants. Those losses in livestock productivity resulted from changes in the biological and physical characteristics of the ecosystems within these regions.

}, doi = {10.1007/978-3-642-79464-3_17}, url = {/files/bibliography/JRN00186.pdf}, author = {Walter G. Whitford}, editor = {D. J. Rapport and C. Gaudet and P. (eds.) Calow} } @inbook {51431, title = {Diversity, spatial variability, and functional roles of invertebrates in desert grassland ecosystems}, booktitle = {The Desert Grassland}, year = {1995}, note = {//NMSU, USDA//LTER III//ProCite field[6]: In}, month = {1995}, pages = {152-195}, publisher = {University of Arizona Press}, organization = {University of Arizona Press}, address = {Tucson, AZ}, abstract = {

Any analysis of the community structure and functional roles of desert grassland invertebrates is constrained by the fact that there are few, if any, patches of grasslands undisturbed by humans and their domestic livestock. The desert grasslands currently exist as scattered patches surrounded by large expanses of desertscrub or as a grassland matrix with shrubs. Much of the area that was desert grassland in the 1850s is now classified as desertscrub (Buffington and Herbel 1965; York and Dick-Peddie 1969). Further, the remaining desert grassland remnants are diverse in terms of soil characteristics and grass species composition. In some areas, exotic introduced grasses have become dominant; in others, remnant grasslands are dominated by species of grasses that are relatively unpalatable to domestic livestock. The invertebrate fauna of desert grasslands is incredibly diverse and includes several phyla. while mammal, bird, reptile, and vascular plant species occur in the tens to hundreds, invertebrate species in desert grasslands number in the thousands or tens of thousands, and many of the less conspicuous species have never been described by taxonomists. Much of this fauna is never seen by the casual observer. If you were asked, "What invertebrates did you see on your morning walk in the desert grassland?" your response would probably be "ants." Ants are the most conspicuous and, along with unseen subterranean termites, the most numerous macroinvertebrates in arid environments. However, the fauna of desert grasslands includes many microscopic organisms and many large but cryptic species as well as the obvious and familiar ones (Crawford 1981; Wallwork 1982). Most of what we know about desert grassland invertebrates and their general life history characteristics is based on data from economically important species (Crawford 1981).

}, keywords = {biodiversity, invertebrates, book, books, chapter, chapters, ecosystem dynamics, invertebrates, grassland, invertebrate community, invertebrate community, invertebrate,grassland, report, reports}, url = {files/bibliography/JRN00188.pdf}, author = {Walter G. Whitford and Gregory S. Forbes and G. I. H. Kerley}, editor = {M.P. McClaran and T.R. Van Devender} } @proceedings {51429, title = {Morphological variation in creosotebush, Larrea tridentata: effects on ecosystem properties}, volume = {Gen. Tech. Rep. INT-GTR-338}, year = {1995}, note = {//NMSU//NONE, LTER//ProCite field[6]: InProCite field[8]: Compilers}, month = {1996}, pages = {195-198}, publisher = {U.S. Department of Agriculture, Forest Service, Intermountain Research Station}, address = {Las Cruces, NM}, abstract = {

Morphological characteristics of creosotebush canopies (angle of exterior stems), size of litter layer and sub-canopy soil chemistry were measured on several sites on the Jornada Experimental Range. Soils under canopies of inverted cone shaped shrubs had little or no litter layer and significantly lower total soil nitrogen and soil carbon than soils under canopies of hemispherically shaped shrubs. In Death Valley, creosotebushes growing in braided washes were predominantly inverted cone shaped. The morphological characteristics of creosotebushes appear to vary with soil type and with mean annual rainfall. The proportional distribution of different morphotypes of creosotebush affects the heterogeneity of creosotebush dominated ecosystems.

}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, Larrea, morphology, precipitation, shrub morphology, proceeding, proceedings, shrub, morphology, soil, shrub morphology}, url = {/files/bibliography/506.pdf}, author = {Walter G. Whitford and E. Martinez-Meza and A.G. de Soyza}, editor = {J.R. Barrow and McArthur, E.D. and R. E. Sosebee and R. J. Tausch} } @article {51430, title = {Persistence of desertified ecosystems: explanations and implications}, journal = {Environmental Monitoring Assessment}, volume = {37}, year = {1995}, month = {1995}, pages = {319-332}, abstract = {

Studies of rainfall partitioning by shrubs, responses of shrub-dominated ecosystems to herbicide treatment, and experiments using drought and supplemental rainfall were conducted to test the hypothesis that the shrub-dominated ecosystems that have replaced desert grasslands are resistant and resilient to disturbance. Between 16 and 25\% of the intercepted rainfall is channelized to deep soil storage by stemflow and root channelization. Stemflow water is nutrient enriched and contributes to the {\textquotedblleft}islands of fertility{\textquotedblright} that develop under desert shrubs. Drought and rainfall augmentation experiments during the growing season after 5 consecutive years of summer drought found that (1) growth of creosotebushes, Larrea tridentata, was not significantly affected, (2) perennial grasses and forbs disappeared on droughted plots, (3) nitrogen mineralization increased in the short term, and (4) densities and biomass of spring annual plants increased on the droughted plots. Doubling summer rainfall for 5 consecutive years had less-significant effects. Coppice dunes treated with herbicide in 1979 to kill mesquite (Prosopis glandulosa) had the same frequency of occurrence of the shrub as the untreated dunes when remeasured in 1993. These data indicate that the shrub-dominated ecosystems persist because they are resistant and resilient to climatic and anthropogenic stresses.

}, keywords = {desertified, ecosystems, explanations, implications}, doi = {DOI: 10.1007/BF00546898}, url = {/files/bibliography/464.pdf}, author = {Walter G. Whitford and G. Martinez-Turanzas and E. Martinez-Meza} } @proceedings {51432, title = {Persistence of desertified ecosystems: Explanations and implications}, volume = {Reprinted from Environmental Monitoring and Assessment, Volume 37, Nos. 1-3, 1995}, year = {1995}, note = { //NMSU, USDA//LTER III//ProCite field[6]: In}, month = {October 24-29, 1}, pages = {319-332}, publisher = {Kluwer Academic Publishers}, address = {Tucson, Arizona}, abstract = { Studies of rainfall partitioning by shrubs, responses of shrub-dominated ecosystems to herbicide treatment, and experiments using drought and supplemental rainfall were done to test the hypothesis that the shrub-dominated ecosystems that have replaced desert grasslands are resistant and resilient to disturbance. Between 16 and 25\% of the intercepted rainfall is channelized to deep soil storage by stemflow and root channelization. Stemflow water is nutrient enriched and contributes to the \"islands of fertility\" that develop under desert shrubs. Drought and rainfall augmentation experiments during the growing season after 5 consectuvie years of summer drought found that (1) growth of creosotebushes, Larrea tridentata, was not significantly affected, (2) perennial grasses and forbs disappeared on droughted plots, (3) nitrogen mineralization increased in the short term, and (4) densities and biomass of spring annual plants increased on the droughted plots. Doubling summer rainfal for 5 consecutive years had less-significant effects. Coppice dunes treated with herbicide in 1979 to kill mesquite (Prosopis glandulosa) had the same frequency of occurrence of the shrub as the untreated dunes when remeasured in 1993. These data indicate that the shrub-dominated ecosystems persist because they are resistant and resilient to climatic and anthropogenic stresses.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, desertification, shrubs, desertification,Prosopis dunelands, herbicide impact, Prosopis duneland, proceeding, proceedings, rainfall simulation,Larrea, shrub, desertification, shrub, stemflow, stemflow, shrub}, isbn = {0-7923-3919-3}, author = {Walter G. Whitford and G. Martinez-Turanzas and E. Martinez-Meza}, editor = {D. A. Mouat and Charles F. Hutchinson} } @article {51427, title = {Variability in soils and vegetation associated with harvester ant (Pogonomyrmex rugosus) nests on a Chihuahuan Desert watershed}, journal = {Biology and Fertility of Soils}, volume = {20}, year = {1995}, month = {1995}, pages = {169-173}, abstract = {

The effects of harvester ant (Pogonomyrmex rugosus) nests on the density and cover of spring annual plants and on soil characteristics were measured at three locations characterized by different soils and dominant vegetation on a desert watershed. There were few differences in vegetation and soils associated with harvester ant nests at locations at the base of the watershed where brief periods of flooding and sediment deposition occur at periodic intervals. At mid-slope locations, there were significant increases in total nitrogen, inorganic phosphorus, and cover (biomass) of four species of spring annuals at the edges of nest disks when compared with reference sites. The spring annuals that exhibited increased cover were species that increase biomass as a function of available nitrogen. At a clay-loam, Scleropogon-Hilaria, grassland site, there were significant reductions in the concentrations of Ca2+ and Mg2+, significant increases in nitrate and total nitrogen, but a significant increase in cover in only one species of annual plant. The data demonstrate that the effects of ants on soil properties and vegetation vary with site location and soil type.

}, keywords = {annual plants, desert, Harvester ants, Pogonomyrmex rugosus, soil nutrients, spatial variability}, doi = {10.1007/BF00336554}, url = {/files/bibliography/463.pdf}, author = {Walter G. Whitford and DiMarco, R.} } @conference {51465, title = {Persistence of desertified ecosystems: explanations and implications}, booktitle = {International Symposium and Workshop on Desertification in Developed Countries: Why Can{\textquoteright}t We Control It?}, year = {1994}, month = {October 24-29, 1}, pages = {18-19}, address = {Tucson, AZ}, abstract = {

Desertification in much of the southwestern U.S. and northern Mexico has resulted in the replacement of perennial grasslands with desert scrublands. Scrublands dominated by C3 shrubs exhibit long-term persistence, resist control efforts, and are resilient in areas where control and revegetation with grasses have been attempted. Experiments using 5 consecutive years of summer drought using \"rain-out\" shelters and 5 consecutive years of approximately doubling the summer rainfall resulted in no significant changes in annual net above-ground primary production of creasotebush, barren tridentata, in either of the treatments. There were significant changes in species composition and above-grind net primary production of spring annual plants and some reduction of perennial grasses and fortis in droughted plots. There were small changes in decomposition rates and nitrogen mineralization potential but no quantitative differences in the Studies of shrub water budgets demonstrated that between 6 percent and 25 percent of the intercepted rainfall was translocated to deep soil storage by stemflow and root channelization. Nutrient minerals in stemflow water on creosotebush were 5 to 10 times more concentrated in stemflow than in thrnttghfsli and bulk precipitation. These data demonstrate that once shrubs are established, islands of resource enrichment of water and nutrients develop under the shrubs. The result is self-reinforcing systems that are resistant to disturbance. The characteristics of the shrub-dominated ecosystems documented in the experiments demonstrate that they are likely to persist with climate change. The data from these studies suggest that management of desertified landscapes in North America should focus on maintaining the residual grasslands and on the economic uses of the shrub-dominated ecosystems.

}, keywords = {desert scrublands, desertification, desertified landscapes, maintaining grasslands, management}, author = {Walter G. Whitford and G. Martinez-Turanzas and E. Martinez-Meza} } @book {51552, title = {Biogeochemical consequences of desertification}, series = {The Science of Global Change, The Impact of Human Activities on the Environment}, year = {1992}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//ProCite field[6]: InProCite field[32]: ASC Symposium Series 483}, month = {1992}, pages = {352-359}, publisher = {American Chemical Society}, organization = {American Chemical Society}, address = {Washington, D. C.}, abstract = {

Processes that reduce the productivity of arid and semi-arid lands, collectively known as desertification, affect more than 3 billion hectares or more than 80\% of such lands. The degradation process results in redistribution of water and nutrients, loss of find soil fractions and replacement of palatable plants with undesirable plants. These changes frequently uncouple rainfall and productivity on a temporal scale. This uncoupling is probably due to modification of the nitrogen cycle as a result of the desertification processes. Changes in vegetation can produce changes in fluxes of radiatively active gasses and a variety of organic volatiles to the atmosphere. Redistribution of soil water may produce "hot" spots for denitrification and for ammonia volatilization that differ in extent both spatially and temporally from undesertified ecosystems. Dust from desertified areas can modify the chemistry of rainfall in areas distant from the dust source.

}, keywords = {biogeochemistry,desertification, book, books, chapter, chapters, community, desertification, desertification, biogeochemistry, report, reports}, doi = {10.1021/bk-1992-0483.ch018}, author = {Walter G. Whitford}, editor = {Dunnette, D. A. and R. J. O{\textquoteright}Brien (eds.)} } @proceedings {51550, title = {Effects of climate change on soil biotic communities and soil processes}, volume = {124-136}, year = {1992}, note = {//??//LTER II//Listed in LTER3 proposal as citing LTER2 support//ProCite field[6]: In}, month = {1992}, publisher = {Yale University Press}, keywords = {abstract, abstracts, climate, soil biota, climate, soil processes, community, soil biota, community,soil biotic, conference, conference proceedings, conferences, proceeding, proceedings, soil processes}, author = {Walter G. Whitford}, editor = {Petters, R. L. and Lovejoy, T. E. (eds.)} } @article {51551, title = {The importance of subterranean termites in semi-arid ecosystems in south-eastern Australia}, journal = {Journal of Arid Environments}, volume = {22}, year = {1992}, note = {//OTHER//NONE//}, month = {1992}, pages = {87-91}, abstract = {

In mulga, Acacia aneura, woodland in north-western New South Wales, Australia, subterranean termites, constructed foraging galleries over organic debris, litter fragments, litter trains, dead wood, dead grass in perennial grass clumps and kangaroo and sheep dung. The larger quantities of litter, litter trains and dead wood in the mulga groves resulted in higher cover of termite gallery sheeting in this habitat, 6.56+-1.02\%, than in the intergrove erosion slopes, 2.2.8+-0.32\%. In the upper 20 cm of soil there were 52.1 storage galleries m-2. In mallee-spinifex habitats in south-western New South Wales, there was no evidence of subterranean termite feeding on dung or the dead stems of spinifex grass, Triodia iritans, but dead stems of mallee, Eucalyptus spp. were galleried and etched by termites. The numbers of sub-surface termite storage galleries in this habitat averaged 137.5 m-2. These galleries ranged between 4.5 and 49.0 cm3. These data suggest that subterranean termites in these Australian ecosystems may be more important as detritivores and in their effects on hydrological properties of soil than has been documented for subterranean termites in the Chihuahuan Desert of North America.

}, keywords = {article, articles, Australia,termites, decomposition,termite, journal, journals, termite,Australia}, doi = {10.1016/S0140-1963(18)30659-1}, url = {files/bibliography/92-JrnArdEnvnmnts-Whitford-2.pdf}, author = {Walter G. Whitford and J. Ludwig and J. Noble} } @article {51598, title = {Subterranean termites and long-term productivity of desert rangelands}, journal = {Sociobiology}, volume = {19}, number = {1}, year = {1991}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1991}, pages = {235-243}, abstract = {

Studies of soil properties, growth and species composition of vegetation, hydrology and patterns of organic matter removal were made on plots where termites had been eliminated and on plots with subterranean termites present. Subterranean termites affected all of the parameters measured. There was a negative correlation between termite abundance/activity and soil organic matter. Soils of termite free plots have lower infiltration and water storage but higher soil nitrogen. These soil properties have an effect on the species composition and productivity vegetation. The importance of subterranean termites as effectors of soil properties and vegetation suggests that these animals are key consumers in desert rangelands.

}, keywords = {article, articles, decomposition, termites, hydrology, infiltration, termites, journal, journals, pesticide, Chlordane, rangeland,productivity,termites, termite, soil organic matter, termite,decomposition, termite,productivity, termites, infiltration}, url = {files/bibliography/JRN00141.pdf}, author = {Walter G. Whitford} } @article {51700, title = {Abiotic controls on the functional structure of soil food webs}, journal = {Biology and Fertility of Soils}, volume = {8}, year = {1989}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {1-6}, abstract = {

The hypothesis that the trophic structure of soil food webs changes as a result of the abiotic environment was examined by reviewing studies of soil biota. In dry soils with a water potential below -1.5 MPa, most bacteria, protozoans, and many species of nematodes are not active. These taxa persist in the soil in a state of anhydrobiosis. Because soil fungi grow at soil water potentials of -6.0 to -8.0 MPa, soil food webs in dry environments appear to be fungal-based and fungal grazers in dry environments appear to be predominantly fungiphagous mites. There is indirect evidence that some species of fungiphagous mites remain inactive in dry soils in a state of "crytobiosis". In habitats where there is insufficient vegetative cover to shade and modify the soil surface, the functional soil food web consists of fungi and a few taxa of soil acari for extended periods of time.

}, keywords = {abiotic,food webs, anhydrobiosis, article, articles, bacteria,food web, cryptobiosis, food web, abiotic controls, fungi,food web, journal, journals, mite,food web, nematode,food web, protozoa,food web, soil, food web}, doi = {10.1007/BF00260508}, url = {files/bibliography/JRN00089.pdf}, author = {Walter G. Whitford} } @article {51697, title = {Contributions of soil fauna to decomposition and mineralization processes in semiarid and arid ecosystems}, journal = {Arid Soil Research and Rehabilitation}, volume = {3}, year = {1989}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {199-215}, abstract = {

This review examines the following questions: (1) do soil fauna play an important regulatory role in decomposition and mineralization processes in arid and semiarid ecosystems? (2) if important, what are the mechanisms of the rate regulation, and (3) what are the management implications of these relationships? Because termites process more than half of the surface litter in hot deserts, this review focuses on faunal effects on buried litter and roots. Elimination of soil arthropods reduced rates of mass loss and coupled mass loss to soil moisture. With arthropods present soil moisture accounted for less than 50\% of the variation in mass loss. Other experiments demonstrated that regulation of mass loss results from predatory mites regulating the population density of grazers, thereby preventing overgrazing of the fungi and bacteria. The regulation of microbial grazers by soil microarthropods also affects rates of mineralization and nutrient immobilization. Populations of small fungus grazing mites (Tarsonomidae) affect mineralization directly. Microarthropods tend to uncouple mineralization from abiotic constraints. Fluctuations in microbial populations and soil fauna are more a function of substrate availability than of abiotic regulation. Pulses in organic matter inputs result in periods of nutrient immobilization, the extent of which is a function of the rate of recovery of populations of key soil microarthropods.

}, keywords = {article, articles, decomposition, belowground, decomposition,soil fauna, journal, journals, microarthropod, also SEE , soil fauna,decomposition, soil fauna,mineralization processes, soil, microarthropods, soil, microbial, soil, mites}, doi = {10.1080/15324988909381199}, url = {files/bibliography/JRN00092.pdf}, author = {Walter G. Whitford and L. W. Parker} } @article {51698, title = {Effects of organic amendments on soil biota on a degraded rangeland}, journal = {Journal of Range Management}, volume = {42}, number = {1}, year = {1989}, note = {//OTHER//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {56-60}, abstract = {

Rehabilitation of degraded rangeland requires rebuilding the soil, including soil biota. In this study wheat straw, bark and wood chips, and dried municipal sludge were placed on native range plots in northcentral New Mexico. Organic amendments had little or no effects of decomposition of straw, litter respiration, soil respiration, biomass of soil microflora, and populations of most of the soil biota in the second year of the study. The differences in soil nematode and microarthropod population densities and straw decomposition occurred only in the bark and wood chip mulched plots in year 1. The absence of differences in year 2 may have been the result of below-average rainfall. The wood chip bark mulch was visibly present at the end of year 2 but the other mulches were not. There may be long-term benefits from application of recalcitrant mulches like wood chips and bark, but the less recalcitrant mulching like straw and low application rates of sludge produce no measurable benefit.

}, keywords = {article, articles, journal, journals, microarthropod,nutrients, nematode,organic amendment, organic amendments, rangeland, microarthropods, soil biota,organic amendments}, doi = {10.2307/3899659 }, url = {files/bibliography/JRN00095.pdf}, author = {Walter G. Whitford and Earl F. Aldon and D. W. Freckman and Yosef Steinberger and L. W. Parker} } @article {51699, title = {Effects of water and nitrogen supplementation on phenology, plant size, tissue nitrogen, and seed yield of Chihuahuan Desert annual plants}, journal = {The Southwestern Naturalist}, volume = {34}, number = {4}, year = {1989}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {546-549}, abstract = {

We measured nitrogen content of plant parts, seed yield, and plant mass of four species of spring annual plants grown under different water and soil nitrogen conditions. We hypothesized that nitrogen would have little effect or a detrimental effect of the nitrogen-fixing legume A. nuttallianus. We hypothesized that water would have the greatest effect of the species of annuals that exhibit little or no growth response to soil nitrogen availability (E. diffusum and E. nuttallianus). Plant tissue nitrogen and seed production were hypothesized to increase in the nitrogen fertilizer-responsive species. L. lasiocarpum and C. stevioides.

}, keywords = {annual plant, biomass, annual plant, nutrient amendment, annual plant, phenology, annual plant, seed yield, annual plant,rainfall simulation, annual plants, biochemistry, article, articles, journal, journals, nitrogen,annual plants, phenology,annual plants, rainfall simulation, annual plants, seed yield,annual plants}, doi = {10.2307/3671516 }, url = {files/bibliography/JRN00096.pdf}, author = {Walter G. Whitford and Julio R. Gutierrez} } @book {51696, title = {The long-term effects of habitat modification on a desert rodent community}, series = {Patterns in the Structure of Mammalian Communities}, volume = {No. 28}, year = {1989}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//ProCite field[6]: In}, month = {1989}, pages = {33-43}, publisher = {Special Publications Museum, Texas Tech University}, organization = {Special Publications Museum, Texas Tech University}, address = {Lubbock, Texas}, abstract = {

Data are presented from the results of a 14-year study of changes in composition of a desert rodent community following habitat perturbation. We studied rodent populations in an area where herbicide treatment reduced shrub cover from 19.7 percent to less than one percent and increased grass cover from 1.3 percent to 22.3 percent. In the first two years following the perturbation, Dipodomys ordii was the most abundant species in the shrub habitats. From 1976 through 1984, the rodent community in both areas was dominated by D. merriami and D. ordii was absent or occurred at low densities in both habitats. Species richness was highest in 1976 and 1985 following successive \"wet\" seasons. In 1985, following three above average wet seasons, D. ordii once again became the most abundant rodent in the grass habitat. Neotoma micropus increased in abundance with increased grass cover. These results suggest interspecific competition between D. ordii and D. merriami during average to dry periods of limited resources. Successive wet seasons allow D. ordii, which has higher fecundity, to increase because resources are not limiting during such periods. Successive wet seasons result in increased species richness due to immigration of opportunistic species like Sigmodon hispidus and Reithrodontomys megalotis.

}, keywords = {book, books, chapter, chapters, Dipodomys,habitat modification, Neotoma,habitat modification, Reithrodontomys,habitat modification, report, reports, rodent community,habitat modification, rodent,habitat modification, Sigmodon,habitat modification}, isbn = {978-0896721739}, url = {files/bibliography/89-PatStrutofMamComm-Whitford.pdf}, author = {Walter G. Whitford and Yosef Steinberger}, editor = {Morris, D. W. and Abramsky, Z. and Fox, B. J. and Michael R. Willig} } @proceedings {51750, title = {Decomposition and nutrient cycling in disturbed arid ecosystems}, year = {1988}, note = {//NMSU//LTER I//ProCite field[6]: In}, month = {1988}, pages = {136-161}, publisher = {Westview Press}, abstract = {

Several studies focused on the effects of organic mulches of soil biota and soil processes in surface mined areas are reviewed. The effects of overgrazing and subsequent rangeland degradation on soil processes are described. Amending mine spoil materials with recalcitrant mulch materials, bark and wood chips, resulted in increased abundances and diversity of soil microflora and microfauna which resulted in decomposition rates similar to unmined soils. Other organic mulches, straw and sewage sludge, had short term or no effect on biota and decomposition. On surface mined areas reconstructed by contouring with a surface layer of topsoil amended with straw, the soil biota and processes were most similar to unmined soil the first year post restoration and diverged greatly by the fourth year. This restoration procedure failed to maintain a viable soil biota. Addition of organic amendments to intact but degraded rangeland had no long-term effect on soil processes, soil biota or vegetative production. In arid rangelands the shift in vegetation from grassland to shrubland has resulted in lowered nitrogen availability as evidenced by low total soil nitrogen and reduced nitrogen mineralization potential.

}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, decomposition, disturbed ecosystem,reclamation, mine reclamation, nitrogen mineralization, nutrient cycling, proceeding, proceedings, rangeland, surface mine reclamation, soil biota, soil restoration}, doi = {10.4324/9780429314216-7}, author = {Walter G. Whitford}, editor = {Allen, E. B. (ed.)} } @article {51749, title = {Decomposition of roots in a Chihuahuan Desert ecosystem}, journal = {Oecologia}, volume = {75}, year = {1988}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1988}, pages = {8-11}, abstract = {

Mass losses of tethered buried roots of two woody shrubs and two herbaceous annuals buried in plots irrigated at 25 mm/moth-1, 6 mm/week-1 and no irrigation were measured. At the end of 1 year, 10-15\% of the mass of the herbaceous annual roots remained and 60\% of the mass of woody shrub roots remained. There were no differences in mass loss attributable to added water. Rates of mass losses of roots in the Chihuahuan Desert were equal to or higher than those reported from mesic ecosystems. Roots of woody shrubs had relatively constant C:N ratios through the experiment. There was significant N immobilization in Baileya multiradiata roots. Percent mass loss of grass roots, Erioneuron pulchellum, and herbaceous annual roots, B. multiradiata, in plots without termites was 15\%. These data suggest that subterranean termites are responsible for most of the mass loss and mineralization of carbon and nitrogen in dead grass and herbaceous roots in the northern Chihuahuan Desert.

}, keywords = {article, articles, decomposition, roots, decomposition,roots, journal, journals, nitrogen immobilization, pesticide, Chlordane, rainfall simulation, decomposition, buried roots, root,decomposition, termite,decomposition}, doi = {10.1007/BF00378807}, url = {files/bibliography/JRN00072.pdf}, author = {Walter G. Whitford and Stinnett, K. and John P. Anderson} } @article {51751, title = {Effects of harvester ant (Pogonomyrmex rugosus) nests on soils and a spring annual, Erodium texanum}, journal = {The Southwestern Naturalist}, volume = {33}, year = {1988}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1988}, pages = {482-485}, abstract = {

Based on the observations of Erodium texanum and the literature, I hypothesized that the density and biomass of E. texanum would be higher around the nest discs of Pogonomyrmex rugosus because of higher soil nutrient levels. Elevated soil nutrients at the edges of mounds of seed harvesting ants have been described in other areas.

}, keywords = {ant nest, Erodium, ant nest, soil effects, ant nests,nutrients, ant, harvester,Pogonomyrmex, article, articles, Erodium,ant nest effects, insect, also SEE , journal, journals, nutrients,ant nests, Pogonomyrmex,soil effects, soil properties, ant nests}, doi = {10.2307/3672218 }, url = {files/bibliography/JRN00077.pdf}, author = {Walter G. Whitford} } @article {51748, title = {Effects of rainfall supplementation on microarthropods on decomposing roots in the Chihuahuan Desert}, journal = {Pedobiologia}, volume = {31}, year = {1988}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1988}, pages = {147-155}, abstract = {

As part of a study designed to test the hypothesis that single large quantity rainfall events would result in higher rates of root decomposition than small frequent rainfall events or no supplemental water, we sampled the microarthropods associated with the decomposing roots. We hypothesized that supplemental water would not only affect the rates of decomposition but would also affect the species composition and biomass of the micrfauna feeding on the microflora on the roots. We further hypothesized that the successional trends in microarthropod populations observed on buried litter by Santos and Whitford (1981) would be similar on decomposing roots.

}, keywords = {article, articles, decomposition, microarthropods, decomposition,roots, journal, journals, microarthropod,decomposition, microarthropod,rainfall simulation, rainfall simulation, microarthropods, rainfall simulation,decomposition, root,decomposition}, doi = {10.1007/BF00378764}, url = {files/bibliography/JRN00078.pdf}, author = {Walter G. Whitford and Stinnet, K. and Yosef Steinberger} } @article {51752, title = {The Jornada LTER site}, journal = {LTER Network News}, volume = {3}, year = {1988}, note = {//NMSU//LTER I//}, month = {1988}, pages = {7}, abstract = {The Jornada LTER has experienced a major change in principle investigators and a modification of program objectives. In January 1988, four new P.I.{\textquoteright}s joined the Jornada team: Dr. William Schlesinger (Duke University); Dr. Wesley Jarrell (University of California-Riverside); Dr. Ross Virginia (San Diego State University); and Dr. Laura Huenneke (New Mexico State University). The modification of program objectives is a change from focusing on hypotheses built around temporal and spatial variability with work focused on a single watershed to hypotheses built around the concept that desertification has changed a previously uniform distribution of resources to a patchy distribution of resources. We hypothesize that this shift in distribution of resources has disrupted temporal linkages among ecosystems and ecosystem processes. In order to address questions concerning desertification processes, we have set up research at several new locations on the Jornada and are working to increase collaborative efforts with the USDA programs at the Jornada.}, keywords = {article, articles, journal, journals, review,Jornada LTER research}, author = {Walter G. Whitford} } @proceedings {51801, title = {How desertification affects nitrogen limitation of primary production of Chihuahuan Desert watersheds}, volume = {General Technical Report RM-150}, year = {1987}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//ProCite field[6]: In}, month = {Octoer 12-16, 19}, pages = {143-153}, publisher = {USDA Forest Service}, address = {Tucson, Arizona}, abstract = {It is hypothesized that the shift from perennial clump grasses to shrub dominated ecosystems in the Chihuahuan Desert has resulted in a change from predominantly water limited ecosystems to nitrogen-water limited ecosystems. In shrublands nitrogen and water are concentrated in patches under individual shrubs. This patchiness affects the temporal linkage between water inputs and nitrogen availability. Nitrogen and water availability are also affected by redistribution of organic matter by wind, water and animals. Shifts from grassland to shrubland results in increased temporal and spatial variability of these essential resources for plant production. Models for predicting primary productivity on desert landscapes must include linkage between mechanistic nitrogen models and broad spatial scale organic matter transport and accumulation models.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, desertification,primary production, model, desertification, model,primary production, nitrogen,primary production, primary production,nitrogen, proceeding, proceedings}, author = {Walter G. Whitford and J. F. Reynolds and Gary L. Cunningham}, editor = {Earl F. Aldon and Carlos E. Gonzale Vicente and Moir, William H. (eds.)} } @book {51865, title = {Decomposition and nutrient cycling in deserts}, series = {Pattern and Process in Desert Ecosystems}, year = {1986}, note = {//NMSU//LTER I//ProCite field[6]: In}, month = {1986}, pages = {93-117}, publisher = {University of New Mexico Press}, organization = {University of New Mexico Press}, address = {Albuquerque, New Mexico}, abstract = {

The results of the recent International Biological Program and other studies suggest that nutrients, especially nitrogen, may limit productivity in desert ecosystems when moisture is available. Few studies examined decomposition processes in desert ecosystems prior to the initiation of our work, but here were fairly extensive efforts focused on nitrogen processes in desert ecosystems as part of the International Biological Program. In this review, I will address the problem of both decomposition and nutrient cycling processes in desert ecosystems and attempt, wherever possible, to demonstrate the relationships between these processes and primary productivity. Since these processes are mediated via the soil biota, I will emphasize soil biotic interactions and their importance, where these are known or suspected.

}, keywords = {book, books, chapter, chapters, decomposition, desertification, decomposition, desertification, mineralization, ecosystem, desertification, nutrient cycling, report, reports}, doi = { 10.1016/B978-012747261-4/50010-9}, url = {files/bibliography/86-EclgyOfDsrtSystm-Whitford.pdf}, author = {Walter G. Whitford}, editor = {Walter G. Whitford} } @proceedings {51863, title = {Pattern in desert ecosystems: water availability and nutrient interactions}, volume = {Vol. 3A/B}, year = {1986}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//ProCite field[6]: In}, month = {1986}, pages = {109-117}, publisher = {Hebrew University Press}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, nutrient, interactions, proceeding, proceedings, water, availability}, author = {Walter G. Whitford} } @article {51862, title = {Rainfall and decomposition in the Chihuahuan desert}, journal = {Oecologia}, volume = {68}, year = {1986}, note = {//NMSU//LTER//}, month = {1986}, pages = {512-515}, abstract = {

We tested the hypothesis that rates of decomposition in a desert should be higher following single large rain events of 25 mm than evenly spaced 6 mm events and that supplemental rainfall should result in higher populations of soil biota. There were no significant differences in mass losses of creosotebush, Larrea tridentata, leaf litter on plots receiving water supplementation and no added water. On some sampling dates, there were higher mass losses in the 6 mm/week-1 treatment. Weekly rainfall produced higher coefficients of variation in mass losses than the other rainfall regimes. A single event pulse compared with weekly pulses of rainfall during the normal "dry" period resulted in no differences in mass losses. Microarthropods and nematodes exhibited numerical responses to supplemental rainfall but the litter microflora did not. These studies provide direct experimental evidence that the conventional wisdom linking decomposition to rainfall in deserts is wrong. The studies also suggest that the effects of litter fauna on surface litter decomposition are minimal; therefore, future studies should focus on activities of the microflora.

}, keywords = {article, articles, decomposition, litter microflora, decomposition, microarthropods, decomposition, nematodes, decomposition,rainfall, journal, journals, Larrea,decomposition, litter,decomposition, microarthropod,decomposition, microarthropod,rainfall simulation, precipitation,decomposition, rainfall simulation, decomposition, rainfall, SEE }, doi = {10.1007/BF00378764}, url = {files/bibliography/JRN00040.pdf}, author = {Walter G. Whitford and Yosef Steinberger and William P. MacKay and L. W. Parker and D. W. Freckman and J. A. Wallwork and Danforth Weems} } @article {51864, title = {Soil movement by desert ants}, journal = {The Southwestern Naturalist}, volume = {31}, year = {1986}, note = {//OTHER//NONE//}, month = {1986}, pages = {273-274}, abstract = {

Estimates of quantities of soil moved by the activities of ants from the soil profiel to the surface in a shinnery oak (Quercus harvardii) - mesquite (Prosopis glandulosa) area 40 km east of Carlsbad, NM. Soils were sandy loams. The average quantity of soil moved to the surface by ants during the period of surface activity (May - September) was 84.2 +/- 4 g m-2.\ 

The area is characterized by spring and summer rainfall 304 mm and a frost free period from March through October. We established twelve permanent 1 m2 plots in which we collected all the new soil of the nests of the ant colonies in these quadrats. This soil was placed in bags identified number, returned to the laboratory, dried and weighed. The quantities of soil (x \± SD) transported from deep in the soil profile to the surface workings (i.e., cleaning tunnels, new chambers, etc.) were as follows: May 8, 17.4 \± June 10, 13.5 \± 8.8 g/m-2; July 10, 2.1 \± 1.8 g/m-2; August 9, 9.8 \± 7.5 g/m-2; and, 26, 43.1 \± 19.1g/m-2.

}, keywords = {ant, soil movement, article, articles, journal, journals, soil movement, ants}, doi = {10.2307/3670582 }, url = {files/bibliography/86-SWNat-Whitford.pdf}, author = {Walter G. Whitford and Douglas Schaefer and Wendy Wisdom} } @proceedings {51982, title = {The contributions of soil fauna to nutrient cycles in desert systems}, year = {1983}, note = { //NMSU//LTER I//ProCite field[6]: In}, month = {19821983}, pages = {49-59}, publisher = {Imprimeur Dieu-Brichart, Ottignies-Louvain-la-Neuve}, address = {Louvain-la-Neuve, Belgium}, abstract = { A significant fraction of the nitrogen turnover and of other nutrients in the Chihuahuan desert is through termites and back to the system by the termite predators. Important fluxes of N through termites include consumption of dead plant material, fixation of atmospheric N by gut symbionts and production of N enriched gallery carton. Use of biocides to eliminate soil fauna showed that nitrogen was immobilized in ephemeral plant roots and absence of microarthropods resulted in marked reduction of nitrogen turnover and increased soil organic nitrogen. In untreated roots, nitrogen fluxes were primarily a function of microarthropod activity but in the absence of microarthropods, bacteriophagous nematodes and protozoans accounted for most of the N fluxes.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, decomposition, nutrient cyling, nematode, nutrient cycling, nitrogen cycling, nutrient cycling, soil fauna, proceeding, proceedings, Prostigmata, soil fauna, nutrient cycling, termite, nutrient cycling}, author = {Walter G. Whitford and D. W. Freckman and L. W. Parker and Douglas Schaefer and Perseu F. Santos and Yosef Steinberger}, editor = {Lebrun, Ph. and Andr{\'e}, H. M. and De Medts, A. and C. Gr{\'e}goire-Wibo, C. and Wauthy, G. (eds.)} } @article {52024, title = {Contributions of subterranean termites to the {\textquoteright}economy{\textquoteright} of Chihuahuan desert ecosystems}, journal = {Oecologia (Berlin)}, volume = {55}, year = {1982}, note = {//NMSU//US-IBP//}, month = {1982}, pages = {298-302}, abstract = {

We examined the role of subterranean termites in decomposition of cattle dung, various herbaceous plant species and wood in a Chihuahuan desert ecosystem. From July-September, termites removed dung at a rate of 0.63 g/day-1 accounting for a percent mass loss of 19.5-100\%. During the autumn subterranean termites consumed more than 50\% of the leaves of the shrub Larrea tridentata, the grass Erioneuron pulchellum and annual plant Lepidium lasiocarpum and Baileya multiradiata but used very little of two other annuals Eriastrum diffusum and Eriogonum trichopes. Yucca inflorescence stalks on plots with termites lost 23\% of their original mass in 30 months while those on termite free soils lost 11\%. Elimination of termites resulted in reduction of fluff grass, Erioneuron pulchellum biomass, thereby affecting the structure of the ecosystem.

}, keywords = {article, articles, decomposition,termites, journal, journals, pesticide, Chlordane, termite,decomposition}, doi = {10.1007/BF00376915}, url = {files/bibliography/82-Oecologia-Whitford.pdf}, author = {Walter G. Whitford and Yosef Steinberger and George Ettershank} } @article {52023, title = {Effects of initial litter accumulation and climate on litter disappearance in a desert ecosystem}, journal = {The American Midland Naturalist}, volume = {108}, number = {1}, year = {1982}, note = {//NMSU//NONE//}, month = {1982}, pages = {105-110}, abstract = {

We examined monthly litter disappearance from initial concentrations of 50g, 100g, 150g and 200g m-2. Approximately 35\%-50\% of the litter disappeared each month from May-September. In March and April litterfall input exceeded litter loss. Litter loss was consistently higher in the 100g m-2 accumulation than from the other concentrations. Stepwise regression analysis showed that litter loss varied as a function of soil temperature at 15 cm (r2= 0.40) and that initial litter quantity was the second most important variable (increased r2 to 0.45). Monthly litter disappearance was apparently independent of monthly rainfall. Abiotic variables gave an r2 of 0.48, suggesting that much of the seasonal variation in litter disappearance is attributable to the soil biota. Suppression of microarthropods by treating the soil with chlordane insecticide resulted in marked reduction in litter disappearance.

}, keywords = {article, articles, decomposition, abiotic factors, decomposition, microarthropods, decomposition,litter, herbicide, chlordane, journal, journals, Larrea,decomposition, litter,decomposition}, doi = { 10.2307/2425298 }, url = {files/bibliography/82-AmMdlndNtrlt-Whitford.pdf}, author = {Walter G. Whitford and Robert Repass and L. W. Parker and Ned Z. Elkins} } @book {52022, title = {The role of nematodes in decomposition in desert ecosystems}, series = {Nematodes in Ecosystems}, year = {1982}, note = {//NMSU//NONE, LTER//ProCite field[6]: In}, month = {1982}, pages = {98-117}, publisher = {University of Texas Press}, organization = {University of Texas Press}, address = {Austin}, abstract = {Although nematodes are numerous in the soils of most ecosystems, their contribution to soil respiration is relatively small (Sohlenius 1980). Thus, judged on the basis of energy flow through an ecosystem, nematodes would have to be considered a minor component of such systems. However, the contribution of a groups of organisms to the functioning of a system cannot be judged solely on the basis of the quantity of energy processed by that group. Chew (1974) suggested that while consumers may be relatively unimportant in energy flow, they may play important roles as rate regulators. In this paper we review our findings to date on the role of nematodes in desert soil ecosystems and show how various guilds of free-living nematodes apparently regulate rates of decomposition, thus eventually affecting nutrient cycling processes.}, keywords = {book, books, chapter, chapters, decomposition,nematodes, nematode,decomposition, pesticide,nematode, report, reports}, author = {Walter G. Whitford and D. W. Freckman and Perseu F. Santos and Ned Z. Elkins and L. W. Parker}, editor = {D. W. Freckman} } @article {52064, title = {Ant communities of southeastern longleaf pine plantations}, journal = {Environmental Entomology}, volume = {10}, number = {2}, year = {1981}, note = {//OTHER//NONE//}, month = {1981}, pages = {183-185}, abstract = {

The ant community in a recent replant longleaf pine plantation on the Savannah River Plant, S.C. had the greatest species diversity and richness when compared to mature, thinned and burned pine plantations. Four species of ants dominated all pine plantations: Crematogaster lineolata (Say), Aphaenogaster traetae Forel, Aphaenogaster fulva Roger and Conomyrma insana Roger. There is an apparent relationship between the channelization of stumps, snags and dead logs by termites and densities of Crematogaster spp. Recent burning of pine straw had no measurable effect on the dominant tree bole/stump nesting species.

}, keywords = {ant community, longleaf pine, article, articles, journal, journals, longleaf pine, ant communities}, doi = {10.1093/ee/10.2.183}, url = {files/bibliography/81-EnvEnt-Whitford.pdf}, author = {Walter G. Whitford and Gentry, J. B.} } @article {52063, title = {Diurnal migration and responses to simulated rainfall in desert soil microarthropods and nematodes}, journal = {Soil Biology and Biochemistry}, volume = {13}, year = {1981}, note = {//LOCAL//NONE//}, month = {1981}, pages = {417-425}, abstract = {

Diurnal patterns of microarthropod abundance in surface leaf litter were related to its moisture content. Leaf litter moisture was nearly 7\% by weight at 0800 h but fell to less than 1 \% by mid-day. Oribatid and tydeid mites moved into litter in the early morning and back into the soil before mid-day. There were no significant differences in numbers of nematodes in litter or soil and 78098\% of the nematodes were anhydrobiotic (coiled) in soil and litter at all times sampled. Following simulated rainfall there were fewer microarthropods in litter at mid-day in the absence of marked decreases in soil and litter moisture content. During drying, there were gradual reductions in numbers and species diversity of litter microarthropods. Nematode numbers did not change as litter dried. Anhydrobiotic nematodes in the soil increased from 14\% on day 1 to 85\% on day 4. Between 24 and 36 h after simulated rainfall, the proportion of anhydrobiotic litter nematodes increased from 35 to 80\%. Within 1 h after simulated rainfall, there were marked increases in numbers and diversity of microarthropods in surface litter. No collembolans were extracted from dry litter controls but the wet litter was dominated by isotomid, sminthurid and onychiurid collembolans. There were increases in numbers and diversity of oribatid, tydeid and gamasid mites in the wet surface litter within 1 h after wetting compared to controls.

}, keywords = {article, articles, journal, journals, microarthropod,diurnal migration, microarthropod,simulated rainfall, nematode,diurnal migration, nematode,rainfall simulation, rainfall simulation}, doi = {10.1016/0038-0717(81)90087-0}, url = {files/bibliography/81-SoilBioandBioChem-Whitford.pdf}, author = {Walter G. Whitford and D. W. Freckman and Ned Z. Elkins and L. W. Parker and Parmalee, Rob and Janice Phillips and Tucker, Suzanne} } @article {52062, title = {Exceptions to the AET model: deserts and clear-cut forest}, journal = {Ecology}, volume = {62}, number = {1}, year = {1981}, note = {//NMSU//NONE//}, month = {1981}, pages = {275-277}, abstract = {

Here, we show that the attractive correlation between AET and decomposition does not necessarily apply to all vegetation types nor to severely disturbed sites. Decomposition is higher than predicted by the AET model in deserts where AET is low, and lower than predicted for a mesic clear-cut forest where AET values are higher than uncut forests. We suggest that the attractive simplicity of the AET decomposition relationship fails in these systems because it does not account for marked changes in microclimate produced by ecosystem perturbation like clear-cutting, or for biotic adaptations in desert ecosystems.

}, keywords = {article, articles, evapotranspiration,model, journal, journals, model, decomposition, model,evapotranspiration}, doi = {10.2307/1936687 }, url = {files/bibliography/81-Ecology62-Whitford.pdf}, author = {Walter G. Whitford and Meentemeyer, V. and Timothy R Seastedt and Cromack, K. Jr. and Crossley, D. A. Jr. and Perseu F. Santos and Todd, R. L. and Waide, J. B.} } @article {52065, title = {Foraging ecology of seed-harvesting ants, Pheidole spp in a Chihuahuan Desert ecosystem}, journal = {The American Midland Naturalist}, volume = {105}, number = {1}, year = {1981}, note = {//NMSU//US-IBP//}, month = {1981}, pages = {159-167}, abstract = {

Seasonal activity, factors affecting foraging activity and forage selection were studied in three species of Pheidole (Hyminoptera: Formicidae) on a watershed in the southern New Mexico Chihuahuan Desert. Pheidole spp. exhibited a seasonal pattern in numbers of active colonies with most colonies active in July coincident with onset of summer rains and seed drop by annual plants. Pheidole militicida occurred only on the deeper soils of the lower watershed while Ph. rugulosa and Ph. xerophila occurred on the entire watershed. The three Pheidole spp. were active only at soil temperatures between 15-35C and were most active at sunrise. Analysis of factors affecting foraging intensity using a stepwise discriminant function and regression showed evaporation and soil surface temperature to be the strongest influences and seed availability to rank second. However, the factors included in the analysis accounted for less than 50\% of the variance in all three species. Pheidole militicida collected mostly forb seeds while Ph. xerophila utilized primarily grass seeds, especially the seeds of fluff grass Erioneuron pulchellum.

}, keywords = {ant, foraging, ant, Pheidole, ant, seed-harvesting, article, articles, journal, journals, Pheidole,foraging}, doi = {10.2307/2425021 }, url = {files/bibliography/81-TheAmMidNtlt-Whitford.pdf}, author = {Walter G. Whitford and D. J. DePree and Hamilton, Patrick and George Ettershank} } @proceedings {52114, title = {Conference Proceedings}, year = {1980}, note = { //NMSU//NONE//ProCite field[2]: Arthropods and detritus decomposition in desert ecosystemsProCite field[6]: In}, month = {July 29 - August}, pages = {770-778}, publisher = {Office of Pesticide and Toxic Substances, Environmental Protection Agency}, address = {Syracuse, New York}, abstract = { Studies of the soil fauna of the worlds\&$\#$39; deserts are limited (Wallwork, 1970, 1972; Wood, 1971; Freckman, Mankau, and Ferris, 1975) and there have been no quantitative studies of the role of soil fauna in decomposition and nutrient release from plant litter. In 1977 we initiated a series of studies to examine the roles of various taxa of desert soil fauna in decomposition and in mineral release processes. In this paper we review selected portions of these studies in order to illustrate the relationships of termites, microarthropods, nematodes and soil microflora in litter decomposition in North American desert ecosystems.}, keywords = {abstract, abstracts, arthropod, decomposition, litter, conference, conference proceedings, conferences, decomposition, litter, microarthropods, decomposition, litter, nematodes, decomposition, litter, soil microflora, decomposition, litter, termites, detritus decomposition, SEE , microarthropod, decomposition, nematode,decomposition, pesticide, Chlordane, proceeding, proceedings, soil microflora,decomposition, termite, decomposition}, author = {Walter G. Whitford and Perseu F. Santos}, editor = {Dindal, Daniel L. (ed.)} } @article {52112, title = {Foraging ecology of two Chihuahuan Desert ant species: Novomessor cockerelli and Novomessor albisetosus}, journal = {Insectes Sociaux}, volume = {27}, number = {2}, year = {1980}, note = {//NMSU//US-IBP//}, month = {1980}, pages = {148-156}, abstract = {

Novomessor albisetosus and N. cockerelli foraged most intensively in the evening and morning at soil surface temperatures between 20 C and 40 C. They were not active in the middle of the night and mid-day. In both species, colonies provided with supplementary seeds increased their foraging intensity. N. cockerelli colonies which were provided with high protein food (tuna fish) extended their foraging time and remained active until soil surface temperatures reached lethal levels. Nearly half of the natural forage of N. cockerelli was insects or insect parts which accounted for only 6.6\% of the forage of N. albisetosus. Approximately 10\% of the workers of N cockerelli entered and were apparently accepted by colonies other then their \"home\" colony. This study demonstrates the importance of both forage availability and forage quality as determinants of activity and forage selection of Novomessor sp.

}, keywords = {ant, Novomessor, ant,foraging, article, articles, foraging,ant, journal, journals, Novomessor,foraging}, issn = {0020-1812}, doi = {10.1007/BF02229250}, url = {files/bibliography/80-Insectes Sociaux-Whitford.pdf}, author = {Walter G. Whitford and Elaine DePree and P. Johnson} } @article {52113, title = {Surface litter breakdown in a Chihuahuan Desert ecosystem}, journal = {Pedobiologia}, volume = {20}, year = {1980}, note = {//NMSU//NONE//}, month = {1980}, pages = {243-245}, abstract = {In a study of distribution patterns of litter and microarthropods we (Santos et al. 1978) found that microarthropod density was highly correlated with amount of surface litter in a Chihuahuan desert creosotebush community. Based on that relationship we hypothesized that the rate of litter decomposition would vary directly with the amount of surface litter present. This paper reports on experiments designed to test that hypothesis and to examine the relationship between quantity of surface litter, microarthropod density and plant growth.}, keywords = {article, articles, decomposition, microarthropod, decomposition,litter, journal, journals, microarthropod, decomposition, pesticide, Chlordane}, author = {Walter G. Whitford and Bryant, Martha and George Ettershank and Jennifer Ettershank and Perseu F. Santos} } @article {52139, title = {Behavior of a predator and its prey: the horned lizard (Phrynosoma cornutum) and harvest ants (Pogonomyrmex spp)}, journal = {Ecology}, volume = {60}, number = {4}, year = {1979}, note = {//NMSU//US-IBP//}, month = {1979}, pages = {686-694}, abstract = {

Horned lizards, Phrynosoma cornutum, were observed between sunrise and sunset in order to record the time spent at different behaviors and the prey taken. Two ant species, Pogonomyrmex desertorum and Pogonomyrmex rugosus, were the most important prey. The behavioral responses of these prey species were studied by subjecting them to varying levels of simulated predation.... The horned lizards have evolved a foraging strategy that allows maximization of prey availability over weeks or a month rather than per hour or day. Estimates of horned lizard densities, ingestion rates, and numbers of potential prey suggest that horned lizard numbers are regulated by the availability and productivity of Pogonomyrmex spp. These estimates also suggest Pogonomyrmex spp. colonies are extremely productive, essentially replacing the entire worker population each year.

}, keywords = {ant,harvester, article, articles, behavior, also SEE , behavior,ants, foraging,ants, journal, journals, lizard, foraging behavior, lizard,horned lizard,Phrynosoma, Phrynosoma,foraging behavior, Pogonomyrmex,predation, predation, lizards-ants, reptile, also SEE }, doi = {10.2307/1936605}, url = {files/bibliography/79-Ecology-Whitford.pdf}, author = {Walter G. Whitford and Bryant, Martha} } @article {52175, title = {Effects of shrub defoliation on grass cover and rodent species in Chihuahuan Desert ecosystem}, journal = {Journal of Arid Environments}, volume = {1}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {237-242}, abstract = {

Treatment of a nine-hectare desert shrub community with an herbicide (dicamba) resulted in reduction of the live canopy of creosotebush, Larrea tridentata, and an increase in coverage of bush muhly, Muhlenbergia porteri. After treatment, Dipodomys merriami was replaced by Dipodomys ordii as the dominant species. On untreated control areas, D. merriami maintained dominance. These changes are interpreted to result from a release of growth inhibition of M. porteri by creosotebush and habitat structure selection in Dipodomys.

}, keywords = {article, articles, Dipodomys,shrub defoliation, grass cover,shrub defoliation, herbicide, dicamba, journal, journals, Larrea,defoliation, Muhlenbergia,shrub defoliation, rodent,shrub defoliation, shrub defoliation, shrub defoliation,grass cover, shrub defoliation,rodents, shrub,defoliation}, url = {files/bibliography/78-.JAE-Whitford.pdf}, author = {Walter G. Whitford and Dick-Peddie, Scott and Walters, David and J. Ludwig} } @article {52176, title = {The effects of twig girdlers (Cerambycidae) and node borers (Bostrichidae) on primary production in mesquite (Prosopis glandulosa)}, journal = {Journal of Arid Environments}, volume = {1}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {345-350}, abstract = {

Production of leaves and shoots on branches of mesquite shrubs which had been girdled by the mesquite twig girdler (Oncideres rhodisticta) was compared with the production of unaffected branches on girdled and ungridled shrubs. We made similar comparisons on mesquite which had been subjected to simulated girdling or terminal node destruction of 40-80 per cent of the branches. There was no significant difference in shoot and leaf growth in either natural or simulated damaged plants compared to controls. These studies suggest that the timing of the activity of stem-destroying insects may be important in minimizing damage to the plant.

}, keywords = {article, articles, Bostrichidae, Cerambycidae, journal, journals, node borer, primary production, Prosopis, Prosopis,node borer, Prosopis,twig girdler, twig girdler}, doi = {10.1016/S0140-1963(18)31715-4}, url = {files/bibliography/78-JournalArdEnvnmnts-Whitford.pdf}, author = {Walter G. Whitford and D. J. DePree and R. K. Johnson} } @proceedings {52172, title = {Foraging by seed-harvest ants}, year = {1978}, note = {//NMSU,USDA//NONE//ProCite field[6]: In}, month = {1978}, pages = {107-110}, publisher = {Cambridge University Press}, abstract = {A review of published studies on the foraging of seed-harvesting ants.}, keywords = {abstract, abstracts, ant, foraging, ant, Novomessor, ant, Pogonomyrmex, ant, Veromessor, conference, conference proceedings, conferences, food habits, also SEE , insect, also SEE , proceeding, proceedings}, author = {Walter G. Whitford}, editor = {Brian, M. V. (ed.)} } @article {52174, title = {Foraging in seed-harvester ants, Pogonomyrmex spp}, journal = {Ecology}, volume = {59}, number = {1}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {185-189}, abstract = {

Pogonomyrmex rugosus, a group forager, foraged preferentially on seeds of plant species which shed large quantities of seeds a 1 time. Pogonomyrmex desertorum, an individual forager took seeds in relation to their availability but concentrated on grass seeds late in the growing season. Pogonomyrmex californicus selected seed species which allowed it to avoid contact with its congeners. During a dry year, P. rugosus exhibited little selectivity, supporting the idea that selectivity should be decreased under conditions of low food abundance. Pogonomyrmex spp. removed a significant fraction of the seed production of only 1 species, Bouteloua barbata. It is suggested that Pogonomyrmex foraging may affect the relative abundance of plant species.

}, keywords = {ant, competition, ant, seed production, ant,foraging, ants, seed selection, article, articles, food habits,ants, journal, journals, Pogonomyrmex,competition, seed, production, seed, selection}, doi = {10.2307/1936647 }, url = {files/bibliography/78-Ecology-Whitford.pdf}, author = {Walter G. Whitford} } @article {52173, title = {Structure and seasonal activity of Chihuahuan Desert ant communities}, journal = {Insectes Sociaux}, volume = {25}, number = {1}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {79-88}, abstract = {

In a desert area with abundant annual plants the largest feeding guild was grammivores (nine species). In an area with few annual plants, the largest feeding guild was omnivores (eight species). Within a guild there is little overlap in body length of workers. Species in which there was overlap in body length of workers exhibited marked differences in diet and seasonal activity. Variation in precipitation and productivity between years resulted in differences in seasonal activity, hence considerable variation in the structure of the ant community through time.

}, keywords = {ant community,behavior, article, articles, community, ant, behavior, gramnivore,ant community, journal, journals, omnivores,ant community}, issn = {0020-1812}, doi = {10.1007/BF02224487}, author = {Walter G. Whitford} } @article {52200, title = {Seasonal and yearly fluctuations in Chihuahuan Desert lizard communities}, journal = {Herpetologica}, volume = {33}, year = {1977}, note = {//NMSU//NONE//}, month = {1977}, pages = {54-65}, abstract = {

Two lizard communities, each consisting of seven residents plus several transient or immigrant species, were studied between 1970 and 1975 on a Chihuahuan desert watershed. Lizard species diversity was correlated with the previous 2 yr rainfall. H\&$\#$39; varied between 1.28 and 1.91. The change in diversity in these lizard communities resulted from the influx of transient species and increase in numbers of resident species during a 2-yr wet period and the reverse during drought periods. The influx of transients and immigrants appeared to be related to the expansion of suitable habitat and the proximity to a source area for immigrants. The density of adult Cnemidophorus tigris nearly doubled in 1 yr which was attributed to above average overwinter survival of hatchlings. Seasonal activity periods of adults and hatchlings were longer during dry years than wet years. During wet years adults and juveniles of most species exhibited allochronic activity. Densities of most resident species varied directly with changes in productivity and relative abundance and activity of arthropods. Sceloporus magister numbers remained relatively constant over the 5 yr and this appeared to be related to availability of suitable habitat.

}, keywords = {article, articles, community, lizard, journal, journals, lizard, community, lizard,Cnemidophorus, lizard,Sceloporus}, url = {files/bibliography/77-Herpetologica-Whitford.pdf}, author = {Walter G. Whitford and Creusere, F. Michael} } @article {52222, title = {Changes in O2 consumption, body water and lipid in burrowed desert juvenile anurans}, journal = {Herpetologica}, volume = {32}, number = {1}, year = {1976}, note = {//NMSU//US-IBP//}, month = {1976}, pages = {23-25}, abstract = {

Juvenile Scaphiopus hammondi, Bufo debilis and Bufo cognatus (1-6 weeks post-metamorphosis) were allowed to burrow in soil containers in an environment chamber adjusted to simulate soil temperature conditions in the field. Approximately 50\% of the S. hammondi survived 6 months during which time body H2O changed from 86\% to 75\% and body lipid from 3.2\% to 2.0\%. Bufo cognatus did not burrow and died within 1 month. Bufo debilis made shallow burrows after the soil was mechanically broken and survived 3 months. O2 consumption of burrowed juvenile S. hammondi was 25\% of nonburrowed. O2 consumption of S. hammondi and the bufonid juveniles was higher than that of adults proportionate to the body size differences.

}, keywords = {amphibian, physiology, anuran, physiology, article, articles, journal, journals}, url = {files/bibliography/76-Hptlg-Whitford.pdf}, author = {Walter G. Whitford and Kenneth H. Meltzer} } @article {52221, title = {Comparative ecology of the harvester ants Pogonomyrmex barbatus (F. Smith) and Pogonomyrmex rugosus (Emery)}, journal = {Insectes Sociaux}, volume = {23}, number = {2}, year = {1976}, note = {//NMSU//US-IBP//}, month = {1976}, pages = {117-132}, abstract = {

Factors affecting local geographic distribution, foraging behavior and activity, forage selection, numbers of foragers per colony, nest spacing and nest structure of Pogonomyrmex rugosus and Pogonomyrmex barbatus were studied. There were seasonal differences in foraging activity. P. barbatus was more active in early summer and foraged at night while P. rugosus was more active in mid-summer foraging at night during July. Both species exhibited forage preference for grass seeds but took a variety of other materials. Where both species inhabited the same area they had an index of overlap for forage of 0.7. The colonies of both species were randomly distributed. Colony density was approximately 20 per hectare in areas supporting one or both species. There was no evidence of intraspecific aggression and foraging areas of colonies of the same species overlapped considerably. P. barbatus and P. rugosus avoid competition by habitat selection. Interspecific aggression probably accounts for the lack of overlap in local distribution.

}, keywords = {ant, distribution,Pogonomyrmex, ant,comparative ecology, ant,foraging behavior,Pogonomyrmex, article, articles, foraging,Pogonomyrmex, journal, journals, Pogonomyrmex,comparative ecology}, url = {files/bibliography/76-Insectes Sociaux-Whitford.pdf}, author = {Walter G. Whitford and P. Johnson and Ramirez, John} } @article {52220, title = {Temporal fluctuations in density and diversity of desert rodent populations}, journal = {Journal of Mammalogy}, volume = {57}, number = {2}, year = {1976}, note = {//NMSU//US-IBP//}, month = {1976}, pages = {351-369}, abstract = {

Species composition and density were studied in two areas on a watershed in the Chihuahuan Desert in southern New Mexico. The upper portion of the watershed, a creosotebush community, supported \"resident\" populations of Dipodomys merriami, Perognathus penicillatus, Neotoma sp., and Onychomys torridus. The lower portion of the watershed, which drained into a grass-covered dry lake, supported Sigmodon hispidus, Reithrodonomys megalotis, Dipodomys ordii, and Spermophilus spilosoma, in addition to the species found in the creosotebush area.... Changes is species diversity in tie was correlated with rainfall and productivity. The dynamics of these Chihuahuan Desert rodent communities are considered in terms of immigration and extinction as the suitability of habitat islands change through time.

}, keywords = {article, articles, community, rodents, demography,rodents, Dipodomys,demography, journal, journals, Neotoma,demography, Perognathus,demography, rodent,demography, rodent,Dipodomys, rodent,Neotoma, rodent,Perognathus, rodent,population dynamics}, doi = {10.2307/1379694}, url = {files/bibliography/76-Journal of Mammalogy-Whitford.pdf}, author = {Walter G. Whitford} } @article {52219, title = {Water loss in Chihuahuan Desert ants}, journal = {Physiological Zoology}, volume = {48}, number = {4}, year = {1976}, note = {//NMSU//US-IBP//}, month = {1976}, pages = {390-397}, abstract = {

This study was designed to evaluate differences in desiccation rates in six species of Chihuahuan desert ants as related to size, foraging behavior, and geographical distribution. During the first 8 h of exposure, all species of seed harvesters had similar desiccation rates, and Formica perpilosa, a plant-exudate feeder, had a higher desiccation rate and lower desiccation resistance than the harvesters. Desiccation rate and desiccation resistance were not correlated with foraging behavior in Pogonomyrmex sp. and Novomessor cockerelli but were similar to those of ants from the Sahara Desert. There was no relationship between body size and desiccation rate and resistance, but female sexuals of N. cockerelli had lower rates and greater resistance than workers and male sexuals of the same species.

}, keywords = {ant,behavior, ant,water loss, article, articles, journal, journals}, url = {files/bibliography/76-Physiological Zoology-Whitford.pdf}, author = {Walter G. Whitford and Carol Ann Kay and Aileen Schumacher} } @article {52258, title = {Comparative ecology of the harvester ants Pogonomyrmex barbatus (F. Smith) and Pogonomyrmex rugosus (Emery)}, year = {1975}, note = {//??//US-IBP//}, month = {1975}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {ant,harvester, book, books, chapter, chapters, pogonomyrmex, report, reports}, isbn = {Research Memorandum 75-28}, author = {Walter G. Whitford and P. Johnson and Ramirez, John} } @article {52257, title = {Factors affecting foraging activity in Chihuahuan Desert harvester ants}, journal = {Environmental Entomology}, volume = {4}, number = {5}, year = {1975}, note = {//NMSU//US-IBP//}, month = {1975}, pages = {689-696}, abstract = {

The foraging activity of 4 species of harvester ants as affected by soil surface temperature, saturation deficit at the soil surface, light and forage availability was studied in a desert grassland area 40 km NNE of Las Cruces, N.M. Pogonomyrmex sp. were capable of locomotor activity at temperatures between ca. 5 and 53 C and Novomessor cockerelli between 4 and 52 C. Pogonomyrmex sp. exhibited maximum foraging intensity at 45 C and N. cockerelli at 20 C. Forager population sizes varied among species: 1000-6000 in P. rugosus, ca. 1000 in P. californicus and N. cockerelli; and ca. 200-600 in P. desertorum. P. rugosus exhibited peak foraging activity and had the greatest number of colonies active following drought periods, ceasing foraging when granaries were filled, and foraged at night during midsummer. P. desertorum and P. californicus were strictly diurnal and did not exhibit hoarding behavior. P. desertorum responded to soil wetting by shifting activity between watered and unwatered controls directly in response to differences in soil surface temperature. Soil wetting stimulated intense activity in P. rugosus at a time when controls were inactive. Foraging in harvester ants seemed to be primarily affected by forage availability, secondarily by microclimate, with historical factors and interspecific competition as contributing parameters in some species.

}, keywords = {ant, foraging, article, articles, foraging,ants, journal, journals, Novomessor,foraging, Pogonomyrmex,foraging}, doi = {10.1093/ee/4.5.689}, url = {files/bibliography/75-EnvEnto-Whitford.pdf}, author = {Walter G. Whitford and George Ettershank} } @article {52256, title = {Foraging behavior of Chihuahuan Desert harvester ants}, journal = {The American Midland Naturalist}, volume = {95}, number = {2}, year = {1975}, note = {//USDA//US-IBP//}, month = {1975}, pages = {455-458}, abstract = {

Foraging behavior was studied on a desert grassland site 40 km NNE of Las Cruces, New Mexico. The number of workers foraging decrease logarithmically with distance from colony when individual seeds were evenly distributed and varied directly with seed density. Some colonies of Pogonomyrmex rugosus exhibited group foraging while others did not. Foraging territories of individual colonies of P. rugosus were irregular in shape and overlapped considerably with foraging territories of adjacent colonies of P. rugosus.

}, keywords = {ant,foraging behavior, article, articles, food habits, also SEE , foraging,Pogonomyrmex, harvester ant,SEE , journal, journals, Novomessor,foraging behavior, pogonomyrmex, Pogonomyrmex,foraging behavior}, doi = {10.2307/2424409 }, url = {files/bibliography/75-AmMidldNat-Whitford.pdf}, author = {Walter G. Whitford} } @article {52254, title = {The impact of consumers in a desert ecosystem}, year = {1975}, note = {//??//US-IBP//}, month = {1975}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, consumers, report, reports}, isbn = {Research Memorandum 75-22}, author = {Walter G. Whitford} } @article {52255, title = {Jornada validation site report}, year = {1975}, note = {//NMSU//US-IBP//}, month = {1975}, institution = {Utah State University}, address = {Logan, Utah}, abstract = {Drought conditions characterized the first six months of 1974-- a continuation of conditions which began in late summer of 1973. Because of drought conditions, there was a virtual absence of spring annuals, and many species of plants such as Panicum obtusum, Hymenoxys odorata, Hilaria mutica, Larrea tridentata, etc., exhibited no growth until after the first rains, July 4. The only plants exhibiting new growth in spring were those which appear to be more independent of water like Prosopis glandulosa and Yucca elata. Mammals and lizards exhibited decreases in species diversity and densities in early summer 1974, but their populations recovered during the wet summer and fall. Ant and termite activity was low or absent depending on the area until after the summer rains started. Termites consumed all species of buried native vegetation and also ate through the control bags s we were unable to obtain quantitative data on feeding rates. Microbial studies continued this year showed little activity during the dry months of January through June. Litter production data followed the phenology of the plants. Larrea tridentata dropped more bark and twigs than the other species studied. On the spray site, we found that the rodent fauna had switched from a desert fauna dominated by Dipodomys merriami and Perognathus penicillatus to a grassland fauna dominated by Dipodomys ordii and Perognathus flavus. This shift was obviously not related to soil differences.}, keywords = {anurans, Bufo, anurans, distribution patterns, anurans, Scaphiopus, anurans, surface activity, bajada, ants, bajada, arthropods, bajada, climate, bajada, decomposition, bajada, herbicides, bajada, insects, bajada, plants, bajada, reptiles, bajada, soil bacteria, bajada, soil enzymes, bajada, soil thermophiles, bajada,birds, bajada,lagomorphs, bajada,rodents, bird, Swainson{\textquoteright}s hawk, food habits, book, books, chapter, chapters, decomposition, termites, food habits, Swainson{\textquoteright}s hawk, playa, ants, playa, arthropods, playa, climatic, playa, decomposition, playa, flooding, playa, insects, playa, microbial activity, playa, plants, playa, productivity, playa, reptiles, playa, rodents, playa,birds, playa,lagomorphs, report, reports, termite, Amitermes, termite, decomposition, termite, Gnathamitermes, termite, Reticulitermes, US-IBP,validation site report}, isbn = {Research Memorandum 75-4}, author = {Walter G. Whitford} } @article {52253, title = {Studies on wood borers, girdlers, and seed predators of mesquite}, year = {1975}, note = {//??//US-IBP//}, month = {1975}, pages = {15-21}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, girdlers, Prosopis, mesquite, plant production,Prosopis, Prosopis,girdlers, Prosopis,seed predators, Prosopis,wood borers, report, reports, seed predators, wood borers}, isbn = {Research Memorandum 75-26}, author = {Walter G. Whitford and R. K. Johnson and D. J. DePree} } @article {52252, title = {US/IBP Desert Biome Research Memorandum 72-26}, year = {1975}, note = {ProCite field[2]: Studies on wood borers, girdlers and seed predators of mesquite.ProCite field[6]: In}, month = {1975}, pages = {15-21 pp.}, edition = {3}, abstract = {The study was designed to determine the response of honey mesquite (Prosopis glandulosa) to varying levels of insect damage. Because of difficulties encountered in getting the insects to affect the plants in varying degrees, damage of the type done by the mesquite twig girdler (Oncideres sp.) and a node borer (family Bostrichidae) was simulated.....}, keywords = {book, books, chapter, chapters, report, reports}, isbn = {Final Report}, author = {Walter G. Whitford and R. K. Johnson and D. J. DePree} } @article {52288, title = {Jornada validation site report}, year = {1974}, note = {//??//US-IBP//}, month = {1974}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, report, reports, US-IBP,validation site report}, isbn = {Research Memorandum 74-4}, author = {Walter G. Whitford} } @article {52321, title = {Air temperatures, air relative humidity, and solar radiation studies at the Jornada site}, year = {1973}, note = {//??//US-IBP//}, month = {1973}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {air temperature, book, books, chapter, chapters, climate, relative humidity, report, reports, solar radiation}, isbn = {Research Memorandum 71-5, 72-4, 73-4, 74-4}, author = {Walter G. Whitford and J. Ludwig} } @article {52323, title = {Annual and perennial grass and forb production in a desert ecosystem}, year = {1973}, note = {//??//US-IBP//}, month = {1973}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, forb,production, grass, production, report, reports}, isbn = {Research Memorandum 73-29}, author = {Walter G. Whitford} } @article {52322, title = {Food items foraged by herbivorous ants in a desert ecosystem}, year = {1973}, note = {//??//US-IBP//}, month = {1973}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {ant, herbivorous, ant,diet, book, books, chapter, chapters, herbivory,ants, report, reports}, isbn = {Research Memorandum 73-29}, author = {Walter G. Whitford} } @article {52320, title = {Forager population estimates in a desert ecosystem}, year = {1973}, note = {//??//US-IBP//}, month = {1973}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, forager population, population,forager, report, reports}, isbn = {Research Memorandum 73-29}, author = {Walter G. Whitford} } @article {52316, title = {Foraging intensity of herbivorous ants in a desert ecosystems}, year = {1973}, note = {//??//US-IBP//}, month = {1973}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {ant,foraging, ant,herbivorous, book, books, chapter, chapters, herbivory,ants, report, reports}, isbn = {Research Memorandum 73-29}, author = {Walter G. Whitford} } @article {52318, title = {Jornada validation site}, year = {1973}, note = {//??//US-IBP//}, month = {1973}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, report, reports, US-IBP,validation site}, isbn = {Research Memorandum 73-4}, author = {Walter G. Whitford} } @article {52317, title = {Nearest neighbors in herbivorous ant colonies}, year = {1973}, note = {//??//US-IBP//}, month = {1973}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {ant colonies, book, books, chapter, chapters, herbivory,ants, report, reports}, isbn = {Research Memorandum 73-32}, author = {Walter G. Whitford} } @article {52319, title = {Soil temperatures at 10 and 50 cm for the Jornada site}, year = {1973}, note = {//??//US-IBP//}, month = {1973}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, report, reports, soil temperature}, isbn = {Research Memorandum 73-4}, author = {Walter G. Whitford and J. Ludwig and T. O{\textquoteright}Laughlin} } @article {52351, title = {Demography and role of herbivorous ants in a desert ecosystem as functions of vegetation, soil and climate variables}, year = {1972}, note = {//??//US-IBP//}, month = {1972}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {ant,demography, ant,herbivorous, book, books, chapter, chapters, demography,ants, herbivory,ants, report, reports}, isbn = {Research Memorandum 72-32}, author = {Walter G. Whitford and George Ettershank} } @article {52349, title = {Intensity of foraging activity as a function of temperature, humidity, light, food availability, and soil moisture in a desert ecosystem}, year = {1972}, note = {//??//US-IBP//}, month = {1972-73}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, foraging activity,abiotic factors, foraging activity,food availability, report, reports}, isbn = {Research Memorandum 72-32, 73-29, 73-32.}, author = {Walter G. Whitford} } @article {52350, title = {Jornada validation site report}, year = {1972}, note = {//??//US-IBP//}, month = {1972}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, report, reports, US-IBP,validation site report}, isbn = {Research Memorandum 72-4}, author = {Walter G. Whitford} } @article {52378, title = {Jornada validation site report}, year = {1971}, note = {//??//US-IBP//}, month = {1971}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, report, reports, US-IBP,validation site report}, isbn = {Research Memorandum 71-4}, author = {Walter G. Whitford} } @article {52379, title = {Oxygen consumption and water metabolism in a carnivorous mouse}, journal = {Comparative Biochemistry and Physiology}, volume = {40A}, year = {1971}, note = {//LOCAL//NONE//}, month = {1971}, pages = {797-803}, abstract = {

1. Unlike most desert rodents, grasshopper mice, Onychomys torridus, exhibited not reduction in basal metabolic rate from that predicted for mice their size and had high pulmocutaneous water loss.

2. Their thermal neutral zone was 30-35 C.

3. Fecal and urinary water losses were a function of water intake.

4. Food intake increased with water deprivation and the mice could maintain their weight on a beef liver diet containing 72\% water.

5. Data from this study suggest that problems of water balance in this species are most severe in winter.

}, keywords = {article, articles, journal, journals, metabolism,Onychomys, Onychomys,physiology, physiology,Onychomys, rodent, grasshopper mouse,Onychomys, rodent,metabolism, rodent,Onychomys}, doi = {10.1016/0300-9629(71)90265-9}, url = {files/bibliography/71-CompBiochemistry\&Physlogy-Whitford.pdf}, author = {Walter G. Whitford and Marsha R. Conley} } @article {52403, title = {Responses of a population of Ambystoma tigrinum to thermal and oxygen gradients}, journal = {Herpetologica}, volume = {26}, number = {3}, year = {1970}, note = {//USDA//NONE//}, month = {1970}, pages = {372-376}, abstract = {

At water temperatures below 15 C, Ambystoma tigrinum moved in response to oxygen and thermal gradients, remaining in shallow water during the day and returning to deep water at night. Under these conditions, activity was reduced. In the absence of thermal and oxygen gradients at water temperatures below 15 C, movements were random. At water temperatures above 15 C, movement was random and activity increased. Temperature appeared to be the most important factor governing winter and spring activity and light seemed most important in governing summer activity.

}, keywords = {Ambystoma,thermoregulation, amphibian, Ambystoma, amphibian, thermoregulation, amphibian,tiger salamander,Ambystoma, article, articles, journal, journals, physiology,amphibians}, url = {files/bibliography/70-Herpetologica-Whitford.pdf}, author = {Walter G. Whitford and Massey, Marvin} } @article {52428, title = {Aerial and aquatic respiration in axolotl and transformed Ambystoma tigrinum}, journal = {Herpetologica}, volume = {24}, number = {3}, year = {1969}, note = {//USDA//NONE//}, month = {1969}, abstract = {

Studies dealing with the role of the skin, lungs, and buccopharyngeal cavity in respiration in salamanders (Whitford and Hutchison, 1963, 1965, and 1966) have been confined to an analysis of gas exchange in an air environment. In the semidesert and desert areas of the Southwest, populations of the tiger salamander, Ambystoma tigrinum, spend much of their life in semi-permanent or permanent bodies of water. Consequently, an evaluation of the role of the various respiratory surfaces in this species must be conducted in an aquatic environment to determine the role of the skin, lungs, and gills in aquatic respiration when the animals are able to obtain atmospheric oxygen by surfacing. In New Mexico some populations are composed of both transformed and neotenic adults (axolotls). The factors leading to the failure of metamorphosis are not know nor is the adaptive significance of neoteny in these populations understood. Studies of gas exchange in both life forms of adult A. tigrinum could aid in an interpretation of ecological and physiological adaptations to pond environments.

}, keywords = {Ambystoma,respiration, amphibian, Ambystoma, amphibian,physiology, article, articles, journal, journals, physiology,amphibian}, url = {files/bibliography/69-Herpetologica-Whitford.pdf}, author = {Walter G. Whitford and Sherman, Robert E.} } @book {52427, title = {Heart rate and changes in body fluids in aestivating toads from xeric habitats}, series = {Physiological Systems in Semiarid Environments}, year = {1969}, note = {//LOCAL//NONE//ProCite field[6]: In}, month = {1969}, pages = {125-133}, publisher = {University of New Mexico Press}, organization = {University of New Mexico Press}, address = {Albuquerque, New Mexico}, abstract = {Mayhew (1965) reported that in parts of California the spadefoot toad Scaphiopus couchi is forced to remain underground for more than 1 year. It is apparent that anurans inhabiting desert environments must have evolved some mechanisms to survive for extended periods of time in underground burrows. Some of the adaptations of the spadefoot toad S. couchi were studied by McClanahan (1967). He found that emerging S. couchi had high concentrations of urea in their body fluids and that water loss in dehydration was principally from interstitial fluids. My studies of burrowed desert anurans were designed to evaluate gross metabolic changes by monitoring heart rate and to observe changes in body fluids during aestivation. These studies should serve as the basis for further studies on the adaptive mechanisms of desert anurans.}, keywords = {amphibian, aestivating toad, anuran, aestivation, anuran, metabolism, book, books, Bufo,physiology, chapter, chapters, metabolism, aestivating toad, physiology,anuran, report, reports, Scaphiopus,physiology}, author = {Walter G. Whitford}, editor = {Hoff, C. C. and Riedesel, M. L. (eds.)} } @article {52443, title = {Physiological responses to temperature and desiccation in the endemic New Mexico plethodontids, Plethodon neomexicanus and Aneides hardii}, journal = {Copeia}, volume = {2}, year = {1968}, note = {//LOCAL//NONE//}, month = {1968}, pages = {247-251}, abstract = {

Measurements of the critical maximum (CTM), oxygen consumption, and heart rate of Plethodon neomexicanus and Aneides hardii were made for comparison with similar data for other members of the family Plethodontidae. At an acclimation temperature of 20 C, the mean CTM for A. hardii was 33.3 C, and for P. neomexicanus, 33.5 C. Mean oxygen consumption increased from 30.9 u1/g/hr at 5 C to 93.9 u1/g/hr at 25 C in A. hardii and from 35.4 u1/g/hr at 5 c to 60.9 u1/g/hr at 25 C in P. neomexicanus. The metabolism-temperature (M-T) curve for P. neomexicanus was similar to that of Desmognathus quadramaculatus, and eastern plethodontid, but the M-T curve of A. hardii was more comparable to that of a lunged salamander. Heart rate increase directly with temperature in both species. The mean heart rate increased from 22/min at 10 C to 64/min at 25 C in A. hardii and from 24/min at 10 C to 73/min at 25 C in P. neomexicanus. The low CTM recorded for these species may be related to the low temperatures characteristic of their microhabitat. The difference in M-T curves in these species may reflect differences in surface area-mass relationships resulting in differences in cutaneous gas exchange.

}, keywords = {amphibian, Aneides, amphibian, physiology, amphibian, Plethodon, amphibian,desiccation, amphibian,salamander,Aneides, amphibian,salamander,Plethodon, Aneides,physiology, article, articles, journal, journals, physiology, amphibian, Plethodon,physiology, salamander, also SEE }, doi = {10.2307/1441750 }, url = {files/bibliography/68-Copeia1_Whitford.pdf}, author = {Walter G. Whitford} } @article {52458, title = {Observations on territoriality and aggressive behavior in the western spadefoot toad (Scaphiopus hammondii)}, journal = {Herpetologica}, volume = {23}, number = {4}, year = {1967}, note = {//LOCAL//NONE//}, month = {1967}, pages = {318}, abstract = {

On 7 June 1967 I had an opportunity to observe the spacing of calling males and aggressive behavior in the western spadefoot toad, Scaphiopus hammondii, while collecting in a flooded pecan grove in Las Cruces, Dona Ana Co., N. M. Soon after entering the grove where a large number of S. hammondii were calling, it was apparent that the distribution of calling males was not random. The rows of pecan trees formed a natural grid which simplified observations of the distribution of calling males. Three or four males called in an area of approximately 440 square feet circumscribed by pecan trees in the corners. The toads were separated from each other by at least 10 feet.

}, keywords = {amphibian, also SEE , anuran, Scaphiopus, anuran,behavior, article, articles, behavior, Scaphiopus, behavior,also SEE , journal, journals, Scaphiopus,behavior}, url = {files/bibliography/67-Herp-Whitford.pdf}, author = {Walter G. Whitford} }