Drought impacts on ecosystem functions of the U.S. National Forests and Grasslands: Part II assessment results and management implications

摘要: The 781,000 km 2 (193 million acre) United States National Forests and Grasslands system (NF) provides important ecosystem services such as clean water supply, timber production, wildlife habitat, recreation opportunities to the American public. Quantifying historical impacts of climate change drought on functions at national scale is essential develop sound forest management watershed restoration plans under a changing climate. This study applied previously validated Water Supply Stress Index model (WaSSI) 170 NFs in conterminous U.S. (CONUS) examine how extreme droughts have affected yield (Q) gross primary productivity (GPP). For each NF, we focused five years with lowest annual SPI3 (Standardized Precipitation 3-month time scale) during 1962–2012. extent measured by number total area has increased last decade. Across all lands CONUS, most past decade occurred 2002, resulting mean reduction Q 32% GPP 20%. individual NFs, average, top-five represented precipitation 145 mm yr 1 (or 22%), causing reductions evap