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Shifting Rainfall Patterns May Change Southern Appalachian Forest Structure

Photo of Cove hardwood forest at Coweeta Experimental Forest in western North Carolina. USDA Forest Service - Paul Bolstad, Bugwood.orgCove hardwood forest at Coweeta Experimental Forest in western North Carolina. USDA Forest Service - Paul Bolstad, Bugwood.orgSnapshot : Changes in rainfall patterns in the southern Appalachians due to climate change could reduce growth in six hardwood tree species common to the region. The findings have implications for forest managers in the southeast, where climate variability such as more extreme storms coupled with increasingly severe droughts could cause major shifts in forest composition and structure.

Principal Investigators(s) :
Elliott, Katherine J. 
Research Location : Coweeta Hydrologic Lab, Otto, NC, USA
Research Station : Southern Research Station (SRS)
Year : 2015
Highlight ID : 917


A Forest Service study recently published in the journal Global Change Biology evaluated climate-driven patterns of growth for six dominant hardwood tree species in the southern Appalachians. The study examined growth in relation to trees' topographic positions on slopes or in coves. Forest Service scientists sampled 465 trees to evaluate tree ring growth in relation to 70 years of on-site climatic data. They found that maple and poplar trees growing on dry sites were the most sensitive to climate, while the oak species were the least sensitive. More importantly, they found that growth in all the species studied, regardless of whether they were positioned on dry or wet sites, was more sensitive to how precipitation was distributed rather than to the total amount of precipitation. Very small storms in the growing season were surprisingly important in maintaining forest growth. Years with low numbers of small storms and long periods between rainfall events resulted in significant reductions in tree growth, with potential declines in forest productivity of 29 percent on upslope sites and 25 percent on cove sites. These findings highlight the importance of small storms and precipitation distribution in the southern Appalachian region.

Forest Service Partners

External Partners

  • Harvard Forest, Harvard University