Submitted to: US-International Association for Landscape Ecology
Publication Type: Abstract Only
Publication Acceptance Date: 3/4/2006
Publication Date: 3/28/2006
Citation: Campanella, A., Bestelmeyer, B., Peters, D. 2006. Landscape variation in desert rodent community response to grassland-shrubland ecotones [abstract]. 21st Annual Symposium of the United States Regional Chapter of the International Association of Landscape Ecology. March 28 - April 1, 2006, San Diego, California. Paper No. 11.
Technical Abstract: Desert rodents exert strong effects on soil, vegetation, and other animals. It has been reported 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. The consistency of such patterns across a landscape, however, 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. Five such ecotones were examined within the same vegetation types and soils (Bouteloua eriopoda and Prosopis glandulosa on coarse loamy Argids). The ecotones are dynamic (with shrubs expanding into grasslands over the last century) but varied in total shrub and grass abundance depending on mesoclimate and disturbance history. Rodents were trapped from 2002-2005 on grids of 96 traps located within each of three positions in each ecotone: grass-dominated, transitional, and shrub-dominated. We found that abundance/density and biomass exhibited inconsistent relationships to position within ecotones, but rodent abundance and sometimes richness and biomass were positively related to shrub cover across the entire landscape over the 3 periods. Species composition was highly variable among ecotones. Perennial grass cover and bare ground cover were not important. We conclude that relative differences in shrub cover within an ecotone are less important for aggregate measures of rodent communities than absolute differences in shrub cover across the landscape. The relationship of rodent composition to vegetation, however, is spatially and temporally variable.