Submitted to: US-International Association for Landscape Ecology
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2002
Publication Date: April 1, 2002
Citation: HOCHSTRASSER, T., PETERS, D.C., BESTELMEYER, B.T. SIMULATING SMALL MAMMAL EFFECTS ON GRASS-SHRUB ECOTONES IN ARID ECOSYSTEMS. 17TH ANNUAL SYMPOSIUM OF THE INTERNATIONAL ASSOCIATION FOR LANDSCAPE ECOLOGY. 2002. ABSTRACT NO. 16. Technical Abstract: Several processes leading to shrub encroachment within semiarid and arid grasslands have been identified. However, the role of small animals in shifting dominance between grasses and shrubs at their ecotones has not been well studied, especially in combination with other factors, such as drought, cattle grazing, and soil properties. These potentially interacting factors may have contributed to contradictory results of studies of animal effects on shrub encroachment. The objective of this study was to evaluate the relative importance of small mammals, climate, and soil properties to shifts in the location and composition of grass-shrub ecotones in the Chihuahuan Desert. We used a simulation model to integrate the effects of these factors on the recruitment, growth, and survival of creosotebush (Larrea tridentata), mesquite (Prosopis glandulosa), and black grama (Bouteloua eriopoda). In particular, we were interested in the positive and negative effects of animals on shrub recruitment and grass survival. Simulated timespans over which shrub encroachment occurred into black grama grassland were different for the two shrub species. Effects of animals varied with the shrub and animal species involved. Using these simulation results, we developed a framework for understanding and predicting the role of small mammals in shrub encroachment.