Terrain and vegetation are tightly coupled. Landscape formation involves slow erosional processes that create a template of water and energy resources to which vegetation responds rapidly. Optimization theory explains terrain as a self-organized system that uses minimal energy to move water and sediment. Long-range connections limit how far a managed system can be deflected from its natural state. Using natural and experimental landscapes, the investigators will test three hypotheses: (1) plants and microbial crusts affect fluvial and hillslope processes that feed back to regulate resource supply; (2) plant responses to resource availability create a ratchet at the community level that controls responses to droughts; and (3) the optimal plant community either maximizes productivity or minimizes the energy embodied in networks of interacting plants. the PIs employ parallel computation to link models of resource supply, terrain, and plant growth. This synthetic work applies generally to disturbance, succession, and responses to land use changes and will involve inter-disciplinary training of undergraduate and graduate students in ecology and computer engineering.