The availability of water to vegetation on seasonally water-stressed ecosystems is highly dependent on the moisture replenishment capacity of soil during the wet season, its residence time after the wet season ends and the reach of vegetation root systems for accessing moisture from deeper and/or laterally distant soil. However, understanding the interplay of these three processes remains an elusive and complicated task. Previous studies have suggested that topography and vegetation cover together may enhance or diminish all of the above, significantly altering the partition of water and energy fluxes of the landscape in headwater basins. In this study we report the results of the implementation of an energy and water flux partitioning method for seasonally water-stressed ecosystems in complex terrain. Using data from a comprehensive network of sensors on headwater basins with variable vegetation cover from both, the northern and southern hemisphere, we attempt to discern for the first time the relative importance of topography, vegetation cover and soil properties on the partition of water fluxes in these type of landscapes. Our results show that seasonally enhanced (diminished) soil evaporation rates dictated by topographic and vegetation cover conditions on equator-facing (pole-facing) slopes affect the availability of water for vegetation use during the dry season. Hence, differentially altering the partition of energy within the basins, suggesting a feedback mechanism that self-reinforces the observed variability of vegetation structure within these landscapes and its differing hydrologic dynamics.
Gutierrez-Jurado, H. A.; Guan, H.; Wang, J.; Wang, H.; Simmons, C. T.; Bras, R. L. (2016): On the coupled effect of topography, vegetation cover, and soil properties on the partition of water and energy fluxes of seasonally water-stressed ecosystems. American Geophysical Union 2016 Fall Meeting, San Francisco, CA.