Sensitivity to Change in Arid Land Ecosystems (SCALE)

旱地生态系统是对变化最敏感的生态系统之一，无论这些变化与人类土地利用活动或气候条件变化有关。这些生态系统的降水量年年变化很大，厄尔尼诺和拉尼娜事件代表了水分输入范围的两个极端。干旱土地上的大多数生态系统过程都受限于短暂的水分脉动。由于水的可获得性对干旱-土地-生态系统过程施加的限制，在不久的将来，与其他全球变化因素相比，水可获得性的变化在干旱-土地生态系统的功能中可能发挥更突出的作用。该尺度项目旨在了解短期降水脉动和较长期降水季节间和年际变化如何影响生态系统的结构和功能。研究人员将研究与碳、水、氮和微量气体通量有关的生态系统功能的变化。该项目的核心思想是气候变化通过改变水分脉冲的大小和分布来影响干旱地区的生态系统。研究人员证实，土壤水分的利用存在物种差异，这意味着随着降水模式的转变，当前物种组成可能长期不稳定。通过一系列的实地实验、实地操作和建模，研究人员将考察气候变化对科罗拉多高原旱地生态系统的影响。

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.