Using Geophysical Measurements to Infer Subsurface Vegetation Patterns and Processes.

In dryland ecosystems, most ecologically relevant patterns and processes occur within the subsurface, where geophysical and biological dynamics are tightly coupled. A clear example is the spatial and temporal distribution of soil moisture, which both determines and is affected by the distribution of plant roots and their hydraulic function. In this manner, the spatial and temporal patterns of water within the soil can be viewed as arising from two interacting, but discrete reservoirs: (1) water contained within the soil matrix itself and (2) water contained within plant roots. Although the coupling between soil moisture and vegetation dynamics is of fundamental importance to emerging ecohydrological research, the indirect nature of most subsurface geophysical measurements makes it difficult to resolve the spatiotemporal determinants of geophysical and biological patterns separately. This is particularly problematic in drylands, where the biological aspect of belowground moisture (i.e. the spatiotemporal dynamics of water contained within plant roots) may be of critical importance for understanding ecosystem function. In this talk, we will discuss current research activities that seek to reveal these critical belowground structure of dryland plant communities using indirect geophysical methods. In addition, we address the influence of these biological patterns on inferred measurements of soil water dynamics.