Patterns of plant available water storage capacity in montane Idaho and California
Water storage in the soil and regolith is an important property of the landscape that links transpiration, plant production, plant drought stress, forest health, and hydrology. We will discuss work to better understand and quantify soil water storage that is ongoing in two montane regions in the Western US. First, we will discuss analyses of the role of plant available water storage across a mosaic of Aspen and Sagebrush plant communities in the Reynolds Creek Experimental Watershed, Idaho. Second, we will take a regional view of the patterns of soil/regolith water storage in montane California. The work at Reynolds Creek uses multiple in-situ measurements, while the analysis across montane California combines in-situ ET observations with remote sensing data from the Moderate Resolution Imaging Spectrometer (MODIS) and gridded climate data (Parameter-elevation Regression on Independent Slopes Model; PRISM) to infer seasonal changes in water storage.
Patterns of water use and ET in Reynolds Creek Aspen and Sagebrush ecosystems underscore the importance of plant available water storage; ET peaks during the dry summer and water is withdrawn from soil/regolith depths exceeding 1.5 m. In montane California, several regional patterns in plant available water storage were evident: (1) large montane water storage was in sharp contrast to nearby interior and low elevation regions where water storage was small, (2) water storage was particularly large in conifer forests, and (3) water storage varied strongly with elevation, particularly in the Sierra Nevada. We discuss a nest of positive feedbacks between climate, vegetation, and soil/regolith water availability that may drive increased water storage. Lastly, we consider links between ecosystem ecology and critical zone science that may improve our understanding of ecosystem processes.