Collaborative Research: Linking Environmental Heterogeneityto Foraging Behavior: Plant Community Geometry and Herbivore Functional Response

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The ecological consequences of heterogeneity in resources depend on the way resources are arranged in space and on the functional properties of organisms seeking them. The PI's derived a model of consumption by herbivores that incorporates variation in spatial arrangements of plants, and velocities and food processing abilities of animals. The model generated the following hypotheses: 1) Increasing patchiness in plant communities causes encounter rate with resources to decline as foraging time increases. 2) The decline in encounter rate is opposed by increasing resource apparency and size. 3) Spatial pattern fails to influence intake rate when resource encounter rate exceeds an animals food processing rate. 4) At a given scale, the influence of spatial pattern on intake rate will be greatest for animals of intermediate body sizes. To test these hypotheses, the PI's will manipulate spatial patterns of resources, resource apparency, and resource size available to herbivores in laboratory and field experiments. Results from these experiments will provide an assessment of the model's ability to predict intake rate of consumers in comparisons with predictions from more traditional predictive theory. %%% The PI's have developed one of the first models that relates resource patchiness, resource abundance, foraging movements of herbivores, and body size to resource acquisition by herbivores. The model has generated a series of testable hypotheses, some of which are unique and counter-intuitive. Tests of these hypotheses will provide an important contribution toward a much needed general theory of herbivore foraging. Results from this research have important implications for landscape scale management of grazing systems, and for a general understanding of foraging behavior in light of the habitat fragmentation currently occurring in many natural systems.