Sensitivity to Change in Arid Land Ecosystems (SCALE)

干旱地区的生态系统对变化最为敏感，无论这些变化是与人类的土地使用活动有关，还是与不断变化的气候条件有关。 这些生态系统每年的降水量变化很大，厄尔尼诺和拉尼娜事件代表了水分输入范围的两个极端。 干旱地区的大多数生态系统过程都局限于短暂的水分脉冲。 由于水的供应对干旱土地生态系统过程的限制，在不久的将来，水供应的变化可能比其他全球变化因素在干旱土地生态系统的运作中发挥更突出的作用。 SCALE项目旨在了解短期降水脉冲和较长期的降水季节和年与年之间的变化如何影响生态系统的结构和功能。 研究人员将研究生态系统功能在碳、水、氮和微量气体通量方面的变化。 该项目的核心思想是，气候变化通过改变湿度脉冲的大小和分布对干旱土地生态系统产生作用。 研究人员已经确定，在利用土壤水分方面存在物种差异，这意味着随着降水模式的转变，当前物种组成可能存在长期不稳定性。 通过一系列的实地实验、实地操作和建模，研究人员将研究气候变化对科罗拉多高原干旱土地生态系统的影响。

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.