Arid-land ecosystems are among the most sensitive to changes, whether these changes are associated with human land-use activities or shifting climate conditions. These ecosystems experience high variability in precipitation from year to year, with El Nino and La Nina events representing two extremes of the range of moisture input. Most ecosystem processes in arid lands are constrained to brief pulses of moisture. Because of the constraints that the availability of water imposes on arid-land-ecosystem processes, changes in water availability are likely to play a much more prominent role in the functioning of arid-land ecosystems in the near future than are other global change factors. The SCALE project is directed at understanding how both short-term precipitation pulses and longer-term season-to-season and year-to-year variability of precipitation affect ecosystem structure and function. The researchers will examine changes in ecosystem function with respect to carbon, water, nitrogen, and trace-gas fluxes. The core idea of this project is that climate change acts on arid-land ecosystems through changes in the magnitudes and distributions of moisture pulses. The researchers have established that there are species differences in use of soil moisture, implying possible long-term instability in current species composition with a shift in precipitation patterns. Though a series of field experiments, field manipulations, and modeling, the researchers will examine the impacts of climate change on arid-land ecosystems on the Colorado Plateau.
