COS 132-1 - Atmospheric water demand and timing regulate temperate forest sensitivity to drought

Thursday, August 10, 2017: 8:00 AM
E145, Oregon Convention Center
Loïc D'Orangeville1,2, Justin Maxwell3, Daniel Kneeshaw1, Neil Pederson4, Louis Duchesne5, Travis Logan6, Daniel Houle5,6, Dominique Arseneault7, Colin M. Beier8, Daniel Bishop9, Daniel L. Druckenbrod10, Shawn Fraver11, Francois Girard12, Joshua Halman13, Christopher F. Hansen14, Justin L. Hart15, Henrik Hartmann16, Margot Kaye17, David Leblanc18, Stefano Manzoni19, Rock Ouimet5, Shelly A. Rayback20, Christine R Rollinson21 and Richard P. Phillips2, (1)Biological Sciences, Université du Québec à Montréal, Montreal, QC, Canada, (2)Biology, Indiana University, Bloomington, IN, (3)Geography, Indiana University, Bloomington, IN, (4)Harvard Forest, Harvard University, Petersham, MA, (5)Direction de la Recherche Forestière, Ministère des Forêts, de la Faune et des Parcs du Québec, Québec City, QC, Canada, (6)Ouranos Climate Change Consortium, Montreal, QC, Canada, (7)Biologie, chimie, géographie, Université du Québec à Rimouski, Rimouski, QC, Canada, (8)College of Environmental Science and Forestry, State University of New York, Syracuse, NY, (9)Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, (10)Geological, Environmental, & Marine Sciences, Rider University, Lawrenceville, NJ, (11)School of Forest Resources, University of Maine, Orono, ME, (12)Geography, Université de Montréal, Montréal, QC, Canada, (13)Vermont Department of Forests, Parks & Recreation, State of Vermont, Essex Junction, VT, (14)Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, VT, (15)Geography, University of Alabama, Tuscaloosa, AL, (16)Biological Processes, Max Planck Institute for Biogeochemistry, Jena, QC, Germany, (17)School of Forest Resources, The Pennsylvania State University, University Park, PA, (18)Biology, Ball State University, Muncie, IN, (19)Department of Physical Geography, Stockholm University, Sweden, (20)Department of Geography, University of Vermont, Burlington, VT, (21)The Morton Arboretum, Lisle, IL

Forest sensitivity to extreme climate events such as drought has long been presumed to hinge on the hydraulic traits of dominant tree species. However, large intraspecific variation in sensitivity suggests the existence of underpinning environmental controls. We matched local site factors with the growth responses to drought of 10,753 trees in the temperate biome of eastern North America (ENA), representing 24 species and 346 stands.


Here we show that the timing of drought and the atmospheric demand for water (i.e., local potential evapotranspiration; PET) are stronger drivers of drought sensitivity than are soil and stand characteristics or plant traits. Across ENA, intraspecific variation in drought sensitivity was equal to or greater than interspecific variation in sensitivity in 21 of 24 species. The impacts of drought were greatest when the droughts occurred during seasonal peaks in radial growth. Further, trees growing in more arid areas (defined by their higher PET) showed the largest growth reductions during drought. We estimate that predicted changes in drought frequency and PET across ENA over the next decades may reduce C uptake by 4-7% annually. Such changes have the potential to offset the gains in C sequestration from longer growing seasons, land use change, rising atmospheric CO2 and/or nitrogen fertilization.