Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America

Authors

Irena F. Creed, Department of Biology, Western UniversityFollow
Adam T. Spargo, Department of Biology, Western University
Julia A. Jones, Oregon State UniversityFollow
Jim M. Buttle, Department of Geography, Trent University
Mary B. Adams, USDA Forest Service, NRS
Fred D. Beall, Natural Resources Canada, Canadian Forest Service
Eric G. Booth, Department of Civil and Environmental Engineering, University of Wisconsin-Madison
John L. Campbell, USDA Forest Service
Dave Clow, Colorado Water Science Center, US Geological Survey
Kelly Elder, Rocky Mountain Research Station, USDA Forest Service
Mark B. Green, Center for the Environment, Plymouth State University
Nancy B. Grimm, School of Life Sciences, Arizona State University
Chelcy Miniat, Coweeta Hydrologic Laboratory, Southern Research Station
Patricia Ramlal, Fisheries and Oceans Canada, Freshwater Institute
Amartya Saha, Global Water for Sustainability Program, Florida International University
Stephen Sebestyen, Center for Research on Ecosystem Change, USDA Forest Service
Dave Spittlehouse, Lands and Natural Resource Operations, BC Ministry of Forests
Shannon Sterling, Department of Earth Science and Environmental Science, Dalhousie University
Mark W. Williams, Department of Geography, University of Colorado-Boulder
Rita Wrinkler, Lands and Natural Resource Operations, BC Ministry of Forests
Huaxia Yao, Dorset Environmental Science Centre, Ontario Ministry of the Environment

Document Type

Article

Date of this Version

2014

Citation

Global Change Biology, 2014

Comments

U.S. Government work

Abstract

Climate warming is projected to affect forest water yields but the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation (d) was defined as a catchment’s change in actual ET divided by P [AET/P; evaporative index (EI)] coincident with a shift from a cool to a warm period – a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of inter annual variation in potential ET divided by P (PET/P; dryness index) to inter annual variation in the EI – high elasticity indicates low d despite large range in drying index (i.e., resilient water yields), low elasticity indicates high d despite small range in drying index (i.e., non-resilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics are limited, we were able to identify some characteristics of response among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer forests included catchments with lowest elasticity and stable to larger water yields. Deciduous forests included catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/deciduous forests included catchments with highest elasticity and stable water yields. Forest type appeared to influence the resilience of catchment water yields to climate warming, with conifer and deciduous catchments more susceptible to climate warming than the more diverse mixed forest catchments.