@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 {49865, title = {Density fractionation and 13C reveal changes in soil carbon following woody encroachment in a desert ecosystem}, journal = {Biogeochemistry}, volume = {112}, year = {2013}, month = {03/2013}, pages = {409-422}, chapter = {409}, abstract = {Woody encroachment has dramatically changed land cover patterns in arid and semiarid systems (drylands) worldwide over the past 150 years. This change is known to influence bulk soil carbon (C) pools, but the implications for dynamics and stability of these pools are not well understood. Working in a Chihuahuan Desert C4 grassland encroached by C3 creosote bush (Larrea tridentata), we used two density fractionation techniques (2 and 7 pool density fractionations) and isotopic analysis to quantify changes in C pools and dynamics among vegetation microsites typical of an encroachment scenario (remnant intact grassland, shrub subcanopies, and in shrub intercanopy spaces within a shrubencroached area). The C concentration of bulk soils varied with microsite, with almost twice the C in shrub subcanopies as in intercanopy spaces or remnant grasslands. Estimated SOC accumulation rates from Larrea encroachment (4.79 g C m-2 year-1 under canopies and 1.75 g C m-2 year-1 when intercanopy losses were taken into account) were lower than reported for higher productivity Prosopis systems, but still represent a potentially large regional C sink. The composition of soil C varied among microsites, with the shrub subcanopy C composed of proportionally more light fraction C (\1.85 g cm-3) and C that was soluble in sodium polytungstate. Grassland soils contained very little carbonate C compared to shrub subcanopies or shrub intercanopy spaces. Stable isotope analyses indicate that inputs from C3 shrubs were incorporated into all density fractions, even in heavy fractions in which shrub inputs did not change overall C concentration. The seven density fractionation yielded unexpected \ð13C patterns, where the two heaviest fractions were strongly depleted in 13C, indicating strong fractionation following organic matter inputs. These results suggest that the utility of isotope mixing models for determining input sources may be limited in systems with similar fractionation patterns. We propose a five pool model for dryland soil C that includes a relatively dynamic light fraction, aggregate and heavy fractions that are stable in size but that reflect dynamic inputs and outputs, a potentially large and seasonally dynamic pool of soluble C, and a large pool of carbonate C. Combined, these results suggest that dryland soil C pools may be more dynamic than previously recognized.}, keywords = {black grama grass, Bouteloua, carbonates, creosotebush, dryland, Jornada, Larrea, soil carbon stabilization, soil organic matter, woody encroachment}, doi = {10.1007/s10533-012-9735-y}, url = {/files/bibliography/13-020.pdf}, author = {Heather L. Throop and Kate Lajtha and Kramer, Marc} } @conference {50133, title = {Shifts in species dominance at a biome transition zone: Importance of asymmetric competition to long-term trends}, booktitle = {2009 LTER All Scientist Meeting}, year = {2009}, abstract = {Landscapes at the Sevilleta LTER site are dominated or codominated by two perennial grasses from different biomes, Bouteloua eriopoda (black grama) from the Chihuahuan Desert and B. gracilis (blue grama) from the shortgrass steppe, and the Chihuahuan Desert shrub Larrea tridentata (creosotebush). We used a long-term removal study to examine inter-specific interactions between these dominant species, and to determine which species would eventually dominate following the removal of the others. Plants of the dominant species were removed from 5 3m x 4m plots in 1995 at five sites that were either dominated by one of the three species (blue grama grasslands, black grama grasslands, cresootebush shrublands) or at ecotones codominated by two species (blue grama/black grama; black grama/creosotebush). Plant cover is estimated annually, and removals have been conducted annually since that time. Results show that removal of black grama has little effect on cover of blue grama whereas removal of blue grama or creosotebush results in marked increases in cover of black grama. Our results show that competition between black grama and either blue grama or creosotebush is asymmetric. These interactions suggest that black grama dominance may be reduced in the future under climate conditions that favor growth of either blue grama or creosotebush since these species can outcompete black grama. Landscape patterns associated with soil texture can also be explained by these interspecific interactions for soil water in this semiarid environment.}, keywords = {asymmetric, B. gracilis, black grama, Bouteloua eriopoda, creosotebush, LTER, Sevilleta}, author = {Debra C. Peters and Jin Yao} } @article {50380, title = {Jackrabbit (Lepus californicus) herbivory changes dominance in desertified Chihuahuan Desert ecosystems.}, journal = {Journal of Arid Environments}, volume = {70}, year = {2007}, month = {03/2007}, pages = {418-426}, abstract = {This study addressed the question: can herbivory by a medium size herbivore, black-tail jackrabbits (Lepus californicus), change dominance in desertified ecosystems dominated by two species of shrubs. Shrubs that were pruned by jackrabbits in plant communities dominated by creosotebush (Larrea tridentate) and tarbush (Flourensia cernua) were compared to shrubs not browsed by the rabbits. In the missed shrub area, herbivory on F. cernua resulted in death of 46.6\% of the shrubs, compared to only 4.8\% of L. tridentate shrubs. There was no evidence of jackrabbit browsing of dead F. cernua in a tarbush monoculture area. The canopy volumes of F. cernua plants that survived repeated browsing were significantly smaller than predicted based on unbrowsed plants with the same basal stem areas. Jackrabbit browsing resulted in increased canopy volume of creosotebush shrubs. Creosotebush average canopy volume significantly exceeded predicted values because of compensatory growth of stems from nodes below the severed point. Close spatial association of lightly browsed creosotebush with heavily browsed tarbush may be a factor contributing to low utilization of creosotebush stems by jackrabbits. Differential browsing by the rabbits is shifting thee ecosystems toward an L. tridentate monoculture.}, keywords = {browsing, compensatory growth, creosotebush, Flourensia cernua, Larrea tridentata, preferential feeding, tarbush}, doi = {10.1016/j.jaridenv.2007.01.009}, url = {/files/bibliography/07-016.pdf}, author = {Roth, G.A. and Walter G. Whitford and Yosef Steinberger} } @article {50567, title = {Loss of phenolic compounds from leaf litter of creosotebush [Larrea tridentata (Sess. \& Moc. ex DC.) Cov] and tarbush (Flourensia cernua DC.)}, journal = {Journal of Arid Environments}, volume = {61}, number = {1}, year = {2005}, month = {April 1, 2005}, pages = {79-91}, abstract = {We examined loss of organic matter and phenolics from leaf litter of two shrubs that are invasive in the Chihuahuan Desert. Fiberglass bags (1-mm mesh) containing creosotebush [The objective of this paper is to provide insights into exotic and native invasive species dynamics using a conceptual model developed from the long history of research on native woody plant invasion into perennial grasslands. We first describe our new conceptual model that focuses on landscape characteristics (spatial configuration and connectivity) interacting with environmental drivers and biotic processes across multiple scales. We then provide support for the model using a long-term dataset from southern New Mexico. Finally, we discuss new insights this model has to offer for understanding, predicting, and managing exotic invasive species dynamics. (Sess. \& Moc. ex DC.) Cov.] or tarbush (Flourensia cernua DC.) leaf litter were placed below shrubs in two positions (soil surface and 5 cm belowground) and removed at several intervals up to 90 days during winter (creosotebush and tarbush) and spring (creosotebush). Over the 90-day sampling interval, organic matter loss from creosotebush and tarbush during the winter sampling period was low for both surface and buried litter, ranging from 1.7-5.2\%. Losses of organic matter from creosotebush litter during the spring were much greater (75.1 and 33.5\% for buried and surface samples, respectively). Total phenolic losses after 90 days were 1.6, 4.8, 21.6, 13.5, 87.1, and 43.5\% for winter buried creosotebush, winter surface creosotebush, winter buried tarbush, winter surface tarbush, spring buried creosotebush, and spring surface creosotebush litter, respectively, while losses of condensed tannins for the same samples were 45.8, 56.1, -34.0, -41.8, 91.1, and 67.4\%. Nordihydroguaiaretic acid loss from creosotebush litter was 25.4, 18.3, 95.2, and 66.7\% for winter buried, winter surface, spring buried, and spring surface samples, respectively, over the 90-day interval. Losses of organic matter and phenolics were generally greater in buried vs. surface and spring vs. winter samples, and losses typically occurred during the last 30-45 days. http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6WH9-4DGW3YW-3-C\&_cdi=6845\&_user=1496926\&_orig=browse\&_coverDate=04\%2F01\%2F2005\&_sk=999389998\&view=c\&wchp=dGLbVlb-zSkzV\&md5=f5a61c1ff74b379cac3f662abc4550b3\&ie=/sdarticle.pdf}, keywords = {creosotebush, Flourensia cernua DC., Larrea tridentata, leaf litter, loss, organic matter, phenolics, tarbush}, url = {/files/bibliography/05-024.pdf}, author = {P.W. Hyder and E.L. Fredrickson and Richard E. Estell and M.E. Lucero and M.D. Remmenga} } @article {50926, title = {Plant species dominance at a grassland-shrubland ecotone: An individual-based gap dynamics model of herbaceous and woody species}, journal = {Ecological Modelling}, volume = {152}, number = {1}, year = {2002}, month = {June 1, 2002}, pages = {5-32}, abstract = {

Transition zones or ecotones between biomes are predicted to be particularly sensitive areas to directional changes in climate. However, for many ecotones, there is little understanding of the key processes that allow dominant species from adjacent biomes to coexist at transition zones and how differences in these processes affect species responses to changes in environmental conditions. The objective of this study was to examine the relationship between plant life history traits and patterns in dominance and composition at a grassland{\textendash}shrubland transition zone in order to predict shifts in dominance with directional changes in climate. It was hypothesized that differences in life history traits allow species from adjacent biomes to coexist at this transition zone, and that these dominance patterns are dynamic through time as a result of species-specific responses to changes in climate. A mixed lifeform individual plant-based gap dynamics model (ECOTONE) was developed to examine consequences of differences in recruitment, resource acquisition, and mortality to patterns in species dominance and composition under a variety of soils and climatic conditions. This model is unique because it represents interactions among multiple potential dominant species that include congeneric species of one lifeform as well as herbaceous and woody lifeforms across multiple spatial scales. Similar to other gap models, ECOTONE simulates the recruitment, growth, and mortality of individual plants on a small plot through time at an annual timestep. ECOTONE differs from other gap models in the degree of detail involved in determining successful recruitment by each species and in the simulation of belowground resources. Individual plant root distributions and resource availability by depth are dynamic. Soil water content is simulated on a daily timestep and nitrogen is simulated monthly. Multiple spatial scales can be simulated using a grid of plots connected by seed dispersal. ECOTONE was parameterized for two soil types at the Sevilleta National Wildlife Refuge (SEV), a site located within the transition zone between two major biomes in North America. Shortgrass steppe communities are dominated by the perennial grass Bouteloua gracilis (blue grama) and Chihuahuan desert communities are dominated by the perennial grass Bouteloua eriopoda (black grama) or the shrub Larrea tridentata (creosotebush). Experiments were conducted to provide key parameters related to recruitment and growth that were supplemented with information from the literature for remaining parameters. Model output was verified using field estimates of cover and biomass for the three dominant species as well as other groups of species. Simulation analyses were conducted under current climate and for a directional change in climate. Nitrogen was assumed constant for all runs to allow a focus on water availability constraints as affected by climate. Under current climatic conditions, simulated biomass on sandy loam soils was dominated by B. eriopoda with smaller biomass of B. gracilis and other species groups. By contrast, simulated biomass on a loamy sand soil was codominated by B. eriopoda and L. tridentata with very small biomass attributed to other species groups. Under a GFDL climate change scenario of increased year-round temperatures and increased summer precipitation, vegetation patterns shifted to a clear dominance of biomass by B. eriopoda on both soil types. These results show that temporal partitioning of soil water is important to codominance by the two Bouteloua species, and that spatial and temporal partitioning of soil water is important for grass{\textendash}shrub interactions. The results also suggest that global climate change may provide a mechanism for the recovery of B. eriopoda following shrub invasion in the Southwestern U.S. Thus, an individual-based modeling approach is capable of representing complex interactions among herbaceous and woody species as well as between congeneric species with different life history traits at a biome transition zone. This modeling approach is useful in improving our understanding of key processes driving these vegetation dynamics as well in predicting shifts in dominance as environmental conditions change in the future.

}, keywords = {Bouteloua species, Chihuahuan Desert, climate change, creosotebush, ECOTONE, shortgrass steppe}, doi = {10.1016/S0304-3800(01)00460-4}, url = {files/bibliography/JRN00362.pdf}, author = {Debra C. Peters} } @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} } @article {51156, title = {Long-term influences of shrub removal and lagomorph exclusion on Chihuahuan Desert vegetation dynamics}, journal = {Journal of Arid Environments}, volume = {42}, number = {3}, year = {1999}, month = {July 1, 1999}, pages = {155-166}, abstract = {

Cover of perennial species in long-term experimental plots in a creosotebush (Larrea tridentata Sess. \& Moc. Ex DC.) dominated community in the Chihuahuan Desert was monitored for 56 years. Sixteen 21{\textperiodcentered}3{\texttimes}21{\textperiodcentered}3 m plots were established in 1938{\textendash}39 to evaluate the effects of lagomorph exclusion and shrub removal. Major dominant shrubs were individually severed at ground level and removed by hand in 1939, and this process was repeated after measuring plant cover in 1947, 1956, 1960, 1967, 1989, and 1995. Lagomorphs were excluded with poultry wire fencing. Shrub removal increased (p<=0{\textperiodcentered}05) the basal cover of two major desert grass species, black grama (Bouteloua eriopoda Torr.) and spike dropseed (Sporobolus contractus A.S. Hitch.) between 1939 and 1995, but differences were not evident until 50 years after initial treatment. Temporal effects of lagomorph exclusion were less pronounced than shrub removal. Clearly, shrub dominance has an extremely important and lasting role in determining vegetation community structure in this arid environment, even when above-ground shrub structures are periodically removed.

}, keywords = {black grama, Bouteloua eriopoda, creosotebush, desert ecology, Larrea tridentata}, doi = {10.1006/jare.1999.0516}, url = {/files/bibliography/660.pdf}, author = {Kris Havstad and Gibbens, Robert P. and Knorr, C.A. and L. W. Murray} } @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} } @inbook {51449, title = {Rangeland cover types of the Southwestern Region: Creosotebush-Tarbush (SRM 508)}, booktitle = {Rangeland Cover Types of the United States}, year = {1994}, month = {1994}, pages = {67-68}, publisher = {Society for Range Management}, organization = {Society for Range Management}, address = {Denver, CO}, keywords = {cover types, creosotebush, rangeland, southwestern region, tarbush}, author = {C.H. Herbel}, editor = {Shiflet, T.N.} } @article {51578, title = {Productivity of creosotebush foliage and associated canopy arthropods along a desert roadside}, journal = {American Midland Naturalist}, volume = {125}, year = {1991}, month = {1991}, pages = {310-322}, abstract = {

A sampling study was designed to test the hypothesis that creosotebush (Larrea tridentata) shrubs along a roadside were larger, more vigorous and supported greater populations of foliage arthropods than shrubs growing 20 m away from the road margin. Structural and chemical attributes of shrubs and associated foliage arthropods were measured. Roadside shrubs were larger, had denser foliage, more flowers, higher foliar nitrogen contents and lower foliar resin contents than shrubs growing away from the road. Foliage arthropod densities were significantly higher on roadside shrubs. Sap-feeding herbivores dominated numerically and accounted for most of the differences in arthropod abundances between roadside and nonroadside shrubs. Numbers of foliage arthropods were positively correlated with shrub size, density and foliar nitrogen contents, and negatively correlated with foliar resin contents. These findings, in concordance with other studies, indicate that in arid environments productive, vigorous plants are preferred hosts for herbivorous insects.

}, keywords = {arthropods, creosotebush}, doi = {10.2307/2426235 }, url = {/files/bibliography/JRN00139.pdf}, author = {David C. Lightfoot and Walter G. Whitford} } @article {51619, title = {Phytophagous insects enhance nitrogen flux in a desert creosotebush community}, journal = {Oecologia}, volume = {82}, year = {1990}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1990}, pages = {18-25}, abstract = {

We tested the hypothesis that herbivorous insects on desert shrubs contribute to short-term nitrogen cycling, and increase rates of nitrogen flux from nutrient rich plants. Creosotebush (Larrea tridentata) shrubs were treated with different combinations of fertilizer and water augmentations, resulting in different levels of foliage production and foliar nitrogen contents. Foliage arthropod populations, and nitrogen in canopy dry throughfall, wet throughfall and stemflow were measured to assess nitrogen flux rates relative to arthropod abundances on manipulated and unmanipulated shrubs over a one-month period during peak productivity. Numbers and biomass of foliage arthropods were significantly higher on fertilized shrubs. Sap-sucking phytophagous insects accounted for the greatest numbers of foliage arthropods, but leaf-chewing phytophagous insects represented the greatest biomass of foliage arthropods. Measured amounts of bulk frass (from leaf-chewing insects) were not significantly different among the various treatments. Amounts of nitrogen from dry and wet throughfall and stemflow were significantly greater under fertilized shrubs due to fine frass input from sap-sucking insects. Increased numbers and biomass of phytophagous insects on fertilized shrubs increased canopy to soil nitrogen flux due to increased levels of herbivory and excrement. Nitrogen excreted by foliage arthropods accounted for about 20\% of the total one month canopy to soil nitrogen flux, while leaf litter accounted fro about 80\%.

}, keywords = {arthropod, also SEE , article, articles, creosotebush, insect, phytophagous, journal, journals, nitrogen amendment, nitrogen cycling, Larrea, nitrogen flux, phytophagous insects, rainfall simulation, water amendment}, doi = {10.1007/BF00318528}, url = {files/bibliography/JRN00126.pdf}, author = {David C. Lightfoot and Walter G. Whitford} } @article {51843, title = {A conceptual model of primary productivity, decomposition, and nitrogen cycling in the Chihuahuan creosotebush desert}, journal = {Tree Physiology}, volume = {2}, year = {1986}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1986}, pages = {215-222}, abstract = {

The conceptual framework for a simulation model of primary productivity, decomposition and nitrogen cycling in a shrub-dominated desert ecosystem in southern New Mexico is presented. This model is based on our previous attempt to simulate carbon allocation patterns in the desert shrub Larrea tridentata Cov., which demonstrated that moisture patterns alone are insufficient to predict desert productivity. These results, as well as others, suggest that mineral nutrients, especially nitrogen, may also be an important determinant of productivity in arid environments. Our current research in the Chihuahuan desert is directed towards elucidating the numerous biotic and abiotic interactions that determine the rates and directions of carbon, nitrogen and water fluxes in this ecosystem. The development of this working model will serve as a tool to accomplish three major objectives: (1) to synthesize the large amounts of existing data on decomposition and nitrogen cycling in deserts, (2) to quantify our present state of knowledge about the structure and function of ecosystem components important in carbon and nitrogen dynamics in deserts, and (3) to address hypotheses concerning the complex mechanisms of interactions and feedbacks among the organisms involved in carbon and nitrogen exchanges in deserts.

}, keywords = {article, articles, creosotebush, decomposition, journal, journals, Larrea, decomposition, Larrea, productivity, Larrea,nitrogen cycling, model, conceptual, model, decomposition, model, Larrea, model, nitrogen cycling, model, primary production, nitrogen cycling, primary production, Larrea}, doi = {10.1093/treephys/2.1-2-3.215}, url = {files/bibliography/JRN00028.pdf}, author = {Daryl L. Moorhead and J. F. Reynolds and Walter G. Whitford} } @proceedings {52154, title = {Arid land seeder}, year = {1978}, month = {1978}, pages = {12}, abstract = {A newly designed grubbing blade developed for front mounting on a rubber tire tractor and patterned after the low-energy gruber{\textquoteright}s blade (crawler tractor) appears very promising for controlling junipers 2 to 5 feet tall. Preliminary data indicate only a slight reduction in acre-per-hour performance while total investment will be approximately one-half. Fuel consumption is 72 percent less than that of a crawler tractor. The farm tractor tested was a 60-horse-power, John Deere 2440 with automatic reverse, foot-controlled throttle, 146 front-end loader frame, and special high-ply, used airplane tires adapted for farm tractors. The rubber-tire grubber averaged 6.3, 1.3, and 0.6 (acres per hour in densities of 50, 250, and 500 trees per acre). Production rates were computed using the curvilinear regression prediction equation Log Y = 2.49 Log X (r = .97) when Y = production (ac/hr) and X = densities/ac. The unit appears well suited to controlling extensive acreages of small junipers infesting previously cleared areas.}, keywords = {arid land seeder, creosotebush, effects on ecosystem}, url = {/files/bibliography/167.pdf}, author = {C.H. Herbel} } @conference {52359, title = {Response of creosotebush to aerially applied herbicide treatments}, booktitle = {Weed Science Society of America Meeting}, year = {1971}, month = {1971}, pages = {No. 127}, keywords = {aerial application, creosotebush, herbicide treatment}, author = {W. L. Gould and C.H. Herbel} } @proceedings {52394, title = {Control of mesquite, creosotebush, and tarbush on arid rangelands of the southwestern United States}, year = {1970}, month = {1970}, pages = {38-41}, address = {Surfers Paradise, Australia}, abstract = {Sparse stands, up to 200 plants per ha, of mesquite, creosote bush and tarbush may be economically controlled with an individual plant treatment of fenuron pellets or other dry herbicides. Aerial spraying with 2, 4, 5-T is also an economical method of reclaiming mesquite-infested areas. The treatment also affords an excellent method of increasing production of perennial grasses.}, keywords = {aerial spraying, arid rangelands, control, creosotebush, fenuron pellets, mesquite, tarbush}, url = {/files/bibliography/125.pdf}, author = {C.H. Herbel and W. L. Gould} } @article {52410, title = {Evaluation of aerial treatments for the control of creosotebush (Larrea tridentata)}, year = {1969}, month = {1969}, pages = {27-28}, institution = {Research Progress Report, Western Society of Weed Science}, abstract = {Creosotebush frequently occurs in almost pure standsin areas of the Southwest where it has invaded. Selective chemical control of creosotebush offers a means for natural revegetation where remnants of perennial grasses remain. This study was initiated to evalute the response of creosotebush to aerial application of materials which had appeared promising in small plot tests.}, keywords = {aerial treatments, creosotebush, Larrea tridentata}, url = {/files/bibliography/112.pdf}, author = {W. L. Gould and C.H. Herbel} } @mastersthesis {52438, title = {Seeding, furrowing, brush removal, and rabbit exclusion effects on creosotebush-infested sites}, year = {1968}, note = {//USDA//NONE//}, month = {1968}, pages = {54}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {

Creosotebush (Larrea tridentata (DC) Cov.) dominates much of the formerly productive rangelands of the southwest. A successful and practical method of eradicating this shrub, followed by revegetation of the area by desirable forage plants, would greatly improve these creosotebush-infested areas for livestock use. The purpose of this factorially designed experiment was to study the effects of seeding, furrowing, brush removal, and rabbit exclusion on three creosotebush-infested sites on the Jornada Experimental Range, Las Cruces, New Mexico. Brush removal consistently decreased the canopy cover of creosotebush and total shrubs, regardless of other treatments. The brush removal alone or the brush removal x rabbit exclusion treatment significantly increased the grass species at the |Ragged and Parker Tank sites. The rabbit exclusion fence was present in the treatment applications that significantly increased the grass cover at the Dona Ana site. This treatment was significant in increasing the grass cover due to its soil retaining and soil depositional effects on this site with the steeper slope and the more severe erosion and runoff condition.

}, keywords = {brush removal, creosotebush, dissertation, dissertations, furrowing, Larrea, revegetation, rabbit exclusion, revegetation, seeding, theses, thesis}, url = {/files/bibliography/1968-1.pdf}, author = {Korzdorfer, Edward Jay} } @article {52468, title = {Creosotebush (Larrea tridentata [DC.] Coville)}, year = {1966}, month = {1966}, pages = {21 }, publisher = {U.S. Department of Agriculture and U.S. Department of the Interior, Chemical Control of Range Weeds, Interagency Report}, abstract = {Creosotebush, a member of the caltrops family, is a common evergreen shrub usually 3 to 6 feet tall. It occurs on an estimated 461/2 million acres in the arid Southwest from California to western Texas. It spreads from seed. This plant is worthless for browsing. Desirable perennial grasses cannot compete with creosotebush. After creosotebush becomes established on a site, it can gain dominance rather rapidly. When this occurs, the entire site deteriorates from wind and water erosion. Individual plant treatment with fenuron pellets have consistently given plant kills in excess of 90 percent. Monuron powder, monuron-trichloroacetate benzoic acid granules have been less effective. An effective rate is an individual plant treatment of 1 gram active ingredient of 25 percent fenuron pellets (1 level teaspoon = 1 gram active ingredient) for each 1{\textonehalf} feet of canopy diameter. The pellets should be scattered around the base of the plant. Since fenuron is desensitized by light and high temperatures, it is important that the materials be applied just prior to or in the early part of an expected rainy season. This is an economical method of controlling sparse stands (up to 75 plants per acre) of creosotebush. It would be especially beneficial where creosotebush is invading grassland. The work reported was done on gravelly sandy loams in southern New Mexico.}, keywords = {creosotebush, description, government publication, Larrea tridentata, plant treatment}, url = {/files/bibliography/095.pdf}, author = {C.H. Herbel} } @article {52471, title = {Germination and growth of some semidesert grassland species treated with aqueous extract from creosotebush}, journal = {Ecology}, volume = {47}, year = {1966}, month = {1966}, pages = {775-781}, abstract = {The effects of aqueous extracts from creosotebush (Larrea tridentafa) material on germination and initial growth of black grama (Bouteloua eriopoda), bush muhly (Muhlenbergia porteri) and creosotebush were studied. There was no apparent difference among extracts obtained from the various creosotebush plant parts. An aqueous extract from leaves and twigs significantly reduced germination of black grama caryopses, but the germination of bush muhly caryopses and creosotebush seeds (removed from the carpels) was not affected. Less concentrated extracts did not significantly reduce germination of the test species. However, radicle and plumule growth of black grama and bush muhly were significantly reduced by all extracts. Apparently, the relatively low osmotic concentrations or the moderate pH{\textquoteright}s were not responsible for these reductions in growth. Comparisons among creosotebush seeds (removed from the carpel) watered with a carpel extract and a water-mannitol solution of the same osmotic concentration and carpels treated with water indicated a structural characteristic or a nonwater-soluble chemical compound in the carpel which inhibits germination of creosotebush. Germination of creosote bush seeds treated with water-mannitol solutions of 1.50, 3.50, 5.00 and 7.00 atm osmotic concentration was significantly reduced as compared to those treated with low concentrations simulating field capacity. Nutrient solution recycled for 37 days around the roots of creosotebush plants growing in a gravel-sand substratum was not inhibitory to germination or initial growth. In a pot test, creosotebush extracts created a crust on the soil surface which reduced the infiltration rate of water. Some of the preceding factors may possibly contribute to the degeneration of grassland areas where creosotebush is present.}, keywords = {aqueous extract, creosotebush, germination, semidesert grassland species}, url = {/files/bibliography/100.pdf}, author = {Knipe, D. and C.H. Herbel} } @article {52476, title = {Vegetational changes on a semidesert grassland range from 1858 to 1963}, journal = {Ecological Monographs}, volume = {35}, number = {2}, year = {1965}, month = {1965}, pages = {139-164}, abstract = {

Extensive areas of the semidesert grassland of the Southwest are dominated by creosotebush [Larrea tridentata (DC) Coville], mesquite [Prosopis julifiora (Swartz) DC], and tarbush (Flourensia cernua DC). Mesquite occurs on 93,000,000 acres; creosotebush is present on 46,500,000; and tarbush occurs on 13,250,000 acres (Platt, 1959). Although the species are indigenous, they have invaded large areas in the past 100 years. Some areas invaded by tarbush still have a good understory of grass. However, loss of forage production occurs in early stages of mesquite invasion (Norris, 1950). In creosotebush-dominated areas, forage production is negligible (Gardner, 1951). The productivity of the rangeland greatly influences the economy of the Southwest. Therefore, it is important for the rancher to conserve and, where necessary, improve the range resource. Some knowledge of original vegetation conditions is essential in properly evaluating the potential of various sites. Much has been written about the semidesert grassland, including quotations from many early travelers. Some authors have based general assumptions on these quotations. However, the quotations are difficult to evaluate properly. In making their observations, many early travelers were influenced by the seasons and by their personal emotions. Furthermore, very few of the areas described by early travelers can actually be relocated for present-day comparisons. This study aims to show the degree of encroachment of brush on the study area and also the nature of the invasion on various soil types. Vegetation surveys of 1858, 1915, 1928, and 1963 were compared. Factors possibly responsible for the changes in vegetation were examined. This study was conducted on the Jornada Experimental Range, which is 23 mi north of Las Cruces, New Mexico.

}, keywords = {brush invasion, creosotebush, mesquite, monograph, semidesert grassland, tarbush, vegetation change}, doi = {10.2307/1948415}, url = {/files/bibliography/091.pdf}, author = {L.C. Buffington and C.H. Herbel} }