Dryland ecosystems are well-known for characteristically large variation in seasonal rainfall. This inter-annual variability leads to highly dynamic systems and allows for a greater diversity of vegetation functional types than would exist in a less heterogeneous environment. However, despite being appreciated as a conceptual tool for understanding dryland function, the specific role of variability in governing the spatial and temporal dynamics of drylands has received little empirical attention. Furthermore, there is a need to develop more general understanding of the couplings between temporal variability in rainfall processes, spatial patterns of vegetation structure, and landscape-scale surface topography. Most studies of variability in rainfall and soil moisture dynamics have attempted to capture either fine-scale spatial heterogeneity caused by vegetation structure (i.e. tree/grass/bare patch differences) or short-term impacts of shits in soil moisture distributions via experimental manipulations. In this talk, I will examine the larger-scale implications of understanding rainfall variability, impacts of variability on the partitioning of surface hydrological fluxes, and subsequent patterns and dynamics of vegetation across a range of ecological settings. Of particular interest is understanding how dryland, tropical, and substistance agricultural landscapes will respond to shifts in rainfall climatology and the landscape-scale spatial organization of coupled vegetation and surface hydrological dynamics.
Results/Conclusions
Using examples from southern and eastern Africa, I present recent work which explores shifts in ecosystem function driven by altered rainfall climatology and leverages novel sensing systems to better understand how to characterize and interpret the emergent patterns that form within highly heterogeneous dryland ecosystems. Patterns of vegetation organization within landscapes across a range of landuse intensity are coupled to high-resolution observations of micro-scale surface topography. The joint distribution of landscape geomorphology and vegetation structure are interpreted within the context of a optimization framework for dryland vegetation that considers both maximization of water use and minization of water stress. These metrics are assessed across a range of scales - from individual, to patch, and hillslope, in order to better understand how shifts in rainfall climatology may be altering the structure and function of dryland ecosystems.