@article {50180, title = {What can ant diversity-energy relationships tell us about land use and land change (Hymenoptera: Formicidae)?}, journal = {Myremecological News}, volume = {11}, year = {2008}, month = {June 28, 2008}, pages = {183-190}, abstract = {We identify and review an approach that views ant species diversity as a consequence of energy flux through an ecosystem. In this bottom-up view, energy apportioned to trophic guilds drives ant community responses to mesoscale variation generated by land-use and other processes. We introduce a conceptual model based upon this idea, and offer an interpretation of some data we have collected in the light of the model. Operationally, the concept focuses analysis upon the relationships between species richness/composition, trophic group identity, body size, and abundance. These attributes are compared among ecosystems that vary in total net primary productivity (NPP) and in how that productivity is divided among plant functional groups. We offer a brief example of how biomass and abundance of three ant trophic groups, large granivores, small granivores and scavengers, differed between two ecosystems that varied strongly in NPP patterns. We emphasize the value of linking ant measurements directly with NPP at mesoscales.}, keywords = {ant, diversity, energy flux, mesocale}, url = {/files/bibliography/08-031.pdf}, author = {Casanova, L.R. and Brandon T Bestelmeyer} } @article {50208, title = {Effects of harvester ant (Messor spp.) activity on soil properties and microbial communities in a Negev Desert ecosystem}, journal = {Biology and Fertility of Soils}, number = {45}, year = {2008}, month = {12/2008}, pages = {165-173}, chapter = {165}, abstract = {

Harvester ants (Messor spp.) function as an essential link between aboveground resources and belowground biota such as the microbial community. We examine changes in soil microbial biomass and functional diversity resulting from harvester ant (Messor spp.) activity in the Negev Desert, Israel. Abiotic and biotic soil parameters were recorded during two seasons {\textendash} wet and dry {\textendash} also representing food availability periods for the ants (low and high seed availability, respectively). Soil samples were collected monthly from the 0- to 10- and 10- to 20-cm soil layers: (1) near the nest entrance, (2) under chaff piles, and (3) at a 2-m radius from the nest entrance (control). Harvester ant activity increased the percentage of organic matter, total soluble nitrogen, and microbial activity in nest-modified soils in comparison to the control soils. Higher CO2 evolution was recorded in the low-seed season in ant nest soils than in the control soils. During the high-seed season, higher carbon dioxide evolution was recorded only at the nest entrance locations. There were no differences in microbial biomass between the low- and high-seed seasons, but highest microbial biomass was found under chaff in low-seed season and in nest soils in high-seed season. Microbial function diversity was higher in nest-modified soils than in the control soils. This study suggests that the effect of harvester ant nests on soil fertility is due to increased microbial biomass and microbial activity in ant nest-modified soils.

}, keywords = {ants, desert system, diversity, Harvester ants, microbial biomass, Negev Desert, soil moisture, soil organic mater}, doi = {10.1007/s00374-008-0309-z}, url = {/files/bibliography/08-042.pdf}, author = {O. Ginzburg and Walter G. Whitford and Yosef Steinberger} } @conference {50272, title = {Does energy flux determine ant diversity? A case study in an arid ecosystem}, booktitle = {93rd Ecological Society of America Annual Meetings}, year = {2008}, month = {August 3, 2008}, pages = {PS 71-14}, abstract = {Ants are highly diverse, widespread, and abundant organisms playing important roles in ecosystem functioning. For these reasons, it is useful to know what structures their diversity. Biodiversity is ultimately constrained by energy availability and the relationship between energy and diversity has been considered at global scales. Energy flux measured as net primary productivity (NPP), however, also varies considerably at landscape scales. In this work, we asked if patterns of ant diversity within a landscape can be predicted by variation in energy flux. To answer this question, we studied ant biodiversity and its relationship to NPP in the Chihuahuan Desert. This study was carried out at the Jornada Basin in southern New Mexico, in a portion of about 100,000 ha that comprises a variety of soils and geomorphology that result in substantial differences in NPP. We measured the peak standing crop biomass (as a proxy for NPP) of 20 sites that comprise 5 different types of vegetation states (grasslands, shrublands and ecotones between them), as well as the richness, abundance and biomass of ants.}, keywords = {ant, diversity, energy}, author = {Rio-Casanova, L. and Brandon T Bestelmeyer} } @conference {50321, title = {Complexity in rodent community respones to grassland-shrubland trasititions}, booktitle = {87th Annual Meeting American Society of Mammalogist}, year = {2007}, month = {June 6-8, 2007}, pages = {p. 89}, address = {Albuquerque, NM}, abstract = {It is believed that the abundance and diversity of Chihuahuan Desert rodents increases with shrub encroachment accompanying desertification although grassland specialist species decline with loss of perennial grasses. It has been reported, however, that a suite of biotic-abiotic interactions may influence rodent population responses to spatial variation in habitat in complex ways, mediating the general habitat/abundance relationship. The consistency of rodent responses to shrub encroachment across a landscape and over time has not been examined in the past and is the objective of this study. Between 2002 and 2006 we monitored rodent populations on five grassland-shrubland ecotone sites in the Jornada Basin (NM, USA). The ecotones are within the same vegetation types and soils (Bouteloua eriopoda and Prosopis glandulosa on coarse loamy Argids), but they are dynamic (with shrubs expanding into grasslands over the last century) and varied in total shrub and grass abundance depending on mesoclimate and disturbance history. We also monitored 23 additional grids distributed across an area of 200 square kilometers and ranging from healthy grasslands to dense mesquite dunes. Precipitation at all sites was recorded. We tested the hypothesis that rodent richness, biomass, and density/abundance were highest in shrub-dominated portions of replicate grassland-shrubland ecotones and across grassland-shrubland transitions. We found that overall rodent richness, biomass and abundance were highly variable across the landscape and responses to shrub cover and precipitation were not always linear across years. Perennial grass cover and bare ground cover did not show significant effects on rodent populations. We conclude that absolute differences in shrub cover across the landscape are more important than relative differences in vegetation structure (i.e. shrub cover) within an ecotone for aggregate measures of rodent communities.}, keywords = {abiotic, biotic, desertification, diversity, rodents}, author = {A. Campanella and Brandon T Bestelmeyer and G. Roemer and Debra C. Peters} } @conference {50320, title = {Rodent community landscape ecology in grassland-shrubland ecotones and gradients in the Chihuahuan Desert}, booktitle = {22nd Annual Symposium of U.S. Regional Chapter of International Association of Landscape Ecology}, year = {2007}, month = {April 9-11, 2007}, pages = {p. 21}, address = {Tucson, AZ}, abstract = {It is believed that the abundance and diversity of Chihuahuan Desert rodents increases with shrub encroachment accompanying desertification although grassland specialist species decline with loss of perennial grasses. It has been reported, however, that rodent population responses to spatial variation in habitat are mediated by a complex suite of biotic-abiotic interactions. The consistency of such patterns across a landscape has not been examined. We tested the hypothesis that rodent richness, biomass, and density/abundance were highest in shrub-dominated portions of replicate grassland-shrubland ecotones and across a grassland-shrubland gradient. Rodents were trapped on permanent grids scattered over an area of 200 km2. Mark-recapture procedures were used to estimate population density and the software eCognition to estimate landscape structure using an object-oriented spatial analysis approach. We found that rodent abundance, biomass, and species composition were highly variable and related to the details of vegetation structure across the landscape, rather than being simply positively correlated with shrub cover.}, keywords = {Chihuahuan Desert, diversity, rodent}, author = {A. Campanella and Brandon T Bestelmeyer and G. Roemer and Debra C. Peters} } @conference {50339, title = {Managing multi-scale diversity to support multiple ecosystem services in complex landscapes}, booktitle = {Ecological Complexity and Sustainability Abstracts of EcoSummit 2007}, year = {2007}, month = {May 22-26, 2007}, pages = {115 CD-ROM}, address = {Beijing, China}, abstract = {Landscapes around the world are undergoing dramatic changes in response to agricultural intensification, expansion, and abandonment. These changes can simultaneously increase and reduce diversity at different scales. The objective of this paper is to explore the relative importance of the nature, scale and pattern of these changes in determining the effects of land use change (LUC) on ecosystem services including food and fiber production, soil and water conservation and carbon sequestration. We will briefly describe three case studies that illustrate the value of considering diversity at multiple scales when assess the effects of LUC in global agroecosystems. These case studies include (1) expansion and mechanization of quinoa production in the southern altiplano of Bolivia, (2) adoption of an agroforestry system in western Honduras and the potential effects of increased livestock use of crop residues, and (3) agricultural land abandonment and changes inland use patterns in northern Mexico. We will also consider how studying the effects of land use changes at different scales can lead to very different conclusions about their effects on different ecosystem services.}, keywords = {diversity, ecosystem, landscapes, LUC, natur, scale}, author = {Kris Havstad and Jeffrey E. Herrick and Brandon T Bestelmeyer and Huber-Sannwald, B.T. and Liberman, M. and M. Ayarza and Joel R. Brown and J. F. Reynolds} } @article {50379, title = {Influence of secondary compound complementarity and species diversity on consumption of Mediterranean shrubs by sheep}, journal = {Applied Animal Behavior Science}, volume = {107}, year = {2007}, month = {September 7, 200}, pages = {58-65}, abstract = {Generalist herbivores foraging in chemically diverse grazing ecosystems like the Mediterranean maquis increase intake on mixed diets, suggesting they are more able to meet nutritional needs and avoid toxicosis. Thus, our objectives were to determine how shrub species diversity and complementary interactions between tannins and saponins influence intake of Mediterranean shrubs by sheep. We conducted four experiments comparing intake of mixtures of Mediterranean shrub mixtures varying in number of species and/or principal class of secondary compound (tannins or saponins) by sheep (n = 12). Sheep consumed more total foliage (P < 0.01) when offered a high-tannin shrub (Pistacia lentiscus; Exp. 1), two high-tannin shrubs (Pistacia lentiscus and Arbutus unedo; Exp.2), or three high-tannin shrubs (Pistacia lentiscus, Arbutus unedo, and Quercus ilex; Exp. 3) when fed in conjunction with a high-saponin shrub (Hedera helix) than with an equal number of high-tannin shrubs (20.94 vs. 16.32 g/kg BW; 28.76 vs. 20.77 g/kg BW, and 35.34 vs. 26.85 g/kg BW). Likewise, sheep ate more foliage (P < 0.01) of each individual shrub (Pistacia lentiscus, Arbutus unedo, and Quercus ilex) in the mixture when fed with Hedera helix than with an equal number of high-tannin shrubs (8.17 vs. 4.95 g/kg BW; 13.28 vs.10.68 g/kg BW, and 7.62 vs. 5.16 g/kg BW), suggesting a complementary interaction between tannins and saponins may have occurred. Sheep also appeared to increase total shrub intake as number of shrub species on offer increased, regardless of number of classes of compounds present. Our findings suggest that secondary compounds in Mediterranean shrubs (tannins and saponins) are complementary. Species diversity also plays an important role in diet selection, as plant species with different types and amounts of nutrients and phytotoxins may affect forage intake and animal production. This knowledge may be useful for livestock producers to capitalize on phytochemical interactions to improve performance of livestock foraging on Mediterranean shrublands.}, keywords = {consumption, diversity, herbivores, mediterranean, sheep}, url = {/files/bibliography/07-025.pdf}, author = {Rogosic, J. and Richard E. Estell and Skobic, D. and Stanic, S.} } @article {50969, title = {Ant biodiversity in semiarid landscape mosaics: The consequences of grazing vs. natural heterogeneity}, journal = {Ecological Applications}, volume = {11}, number = {4}, year = {2001}, month = {August 1, 2001}, pages = {1123-1140}, abstract = {

Conservation of biodiversity in landscape mosaics requires us to understand the impacts of human land use within mosaic elements and an evaluation of the biological uniqueness of different elements. We examined patterns of ant diversity in three semiarid rangeland landscapes used predominantly for grazing. Within each landscape, we compared the effects of grazing and natural variation in soils and vegetation on ant diversity and community composition. Grazing had little effect on ant richness, diversity, or composition at the transitional zone or the desert grassland site; but, ungrazed areas at the shortgrass steppe site had a higher overall richness and favored the abundance of some species. Some samples of saltbush (Atriplex canescens) shrubland were similar to ungrazed samples in richness and species composition. In both the transitional zone and the desert grassland, creosotebush (Larrea tridentata)-dominated habitats harbored comparatively species-rich and distinct ant communities. Also, mesquite (Prosopis glandulosa) coppice dunes at the desert grassland site favored the abundance of several rare species. Canonical correspondence analysis revealed that variation in soil hardness and texture best explained community variation at the shortgrass steppe site, whereas soil texture and associated differences in shrub density best explained differences in composition at the transitional and desert grassland sites. While habitat characterization based on vegetation classification did not adequately reflect environmental variation important to ants in shortgrass steppe, it reflected important soil textural variation in the transitional and desert grassland sites. This suggests that ant conservation in these semiarid rangelands should emphasize patterns of variation in soil properties.

}, keywords = {ants, canonical correspondence analysis, desert grassland, diversity, formicidae, grazing, habitat classification, shortgrass steppe, soil texture}, doi = {10.1890/1051-0761(2001)011[1123:ABISLM]2.0.CO;2}, url = {/files/bibliography/01-014.pdf}, author = {Brandon T Bestelmeyer and J.A. Wiens} } @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} }