Warming temperature homogenizes landscape vegetation patterns at the catchment scale

Authors: Taehee Hwang*, Indiana University, Lawrence E Band, University of North Carolina at Chapel Hill, Chelcy F Miniat, Coweeta Hydrologic Laboratory, USDA Forest Services, Jennifer D Kneopp, Coweeta Hydrologic Laboratory, USDA Forest Service, James M Vose, Center for Integrated Forest Science, USDA Forest Service, , Conghe Song, University of North Carolina at Chapel Hill, Paul V Bolstad, University of Minnesota
Topics: Biogeography, Water Resources and Hydrology, Remote Sensing
Keywords: Biogeography, Landsat, Catchment, Climate Change
Session Type: Paper
Day: 4/10/2018
Start / End Time: 8:00 AM / 9:40 AM
Room: Zulu, Sheraton, 8th Floor
Presentation File: No File Uploaded

Hydroclimate change is expected to bring warmer temperatures and increased hydrologic extremes, including more intense precipitation and longer interstorm periods. In mountainous headwater catchments, downslope flow could mitigate the impact of dry periods in convergent topographic areas, buffering vegetation species from soil moisture stress during drought. Here we investigate changes in catchment-scale vegetation patterns in six forested headwater catchments in the Coweeta Hydrologic Laboratory in the southern Appalachian Mountains. We use a 30-year Landsat Thematic Mapper (TM) image record, spanning a period of recorded warming from the mid-1980s to present, and relate these long-term vegetation dynamics to seasonal water balance and low flow dynamics. Contrary to expectation, upslope vegetation showed a greater response to warming, compared downslope, also supported by long-term tree and litterfall data in one of the reference watersheds (20 years). This indicates that vegetation density (leaf area) patterns paths have been homogenized along hydrologic flow over time. In contrast to our expectations, the vegetation downslope may be experiencing lower growth with increased drought conditions than upslope vegetation, due to their strong dependency on upslope water subsidy.

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