Sensitivity of Sapling and Mature-Tree Water Use to Altered Precipitation Regimes

Abstract

Long-term shifts in precipitation caused by changes in regional or global climate could exert a profound influence on the hydrologic regimes of terrestrial ecosystems. Increases and decreases in precipitation could result in altered patterns of runoff, evaporation, and soil-water content, and, in turn, these changes could have serious implications for catchment water yield, hydrologic budgets across broad spatial scales, impacts on terrestrial Vegetation, and consequences for ecosystem goods and Services upon which society depends. Because of their spatial extent, forests are especially important in this regard, and studies have implied that forests may be particularly vulnerable to changes in soil-water content as evidenced by results from manipulative studies on large trees (Cermák et al. 1993; Cienciala et al. 1994; Irvine et al. 1998; Phillips et al. 2001), field investigations on seedlings and saplings (Abrams et al. 1990, Kubiske and Abrams 1994), and Computer simulations (Pastor and Post 1988; Running and Nemani 1991; Lüdeke et al. 1995). However, few studies have identified the relative sensitivity of multiple species to altered precipitation regimes and then integrated those sensitivities both for the forest overstory and understory into a picture depicting how species and climatic change may potentially impact forest water use in the future.