Vegetation-water budget interactions: Implications for ecosystem dynamics at multiple scales

TitleVegetation-water budget interactions: Implications for ecosystem dynamics at multiple scales
Publication TypeConference Paper
Year of Publication2004
AuthorsPeters DC, Snyder K.A, Wainwright J, Parsons A.J.
Conference Name89th Annual Meeting, Ecological Society of America
Date PublishedAugust 1, 2004
Conference LocationPortland, OR
ARIS Log Number162791
AbstractLandscape-scale water budgets are often assumed to be driven by broad-scale gradients in topo-edaphic factors that influence run-on, runoff, and local plant available water. Feedbacks between vegetation and hydrologic processes are typically ignored. However, in arid landscapes interactions between vegetation type, soil properties, and hydrologic processes can significantly affect plant available water with effects on production at multiple scales. Our goal was to develop a framework for predicting ecologically meaningful water budgets and plant biomass for heterogeneous landscapes using information from processes operating at finer spatial scales (plant, patch). We examined the role of fine-scale vegetation-soil process interactions and topo-edaphic factors in generating patch and landscape-scale hydrology with feedbacks to vegetation. We assessed the importance of these processes on the dynamics of 'beads'---small patches of vegetation (< 100 m2) and microtopography interspersed across Chihuahuan Desert bajada landscapes. Fine-scale processes associated with plant canopies versus bare soil areas significantly affect run-on/runoff patterns and the 'fate' of soil water (i.e., whether water is used for plant transpiration and production or lost to evaporation). Increasing plant cover is associated with increased 'trapping' of soil water with effects on the ratio of evaporation to transpiration. We used a spatially interactive simulation model to integrate fine-scale processes to broader scales and to predict the consequences for vegetation cover of beads and associated landscapes. The consequences of 'missing' the presence and function of beads and other fine-scale water catchment areas in developing landscape-scale water budgets is discussed.