Tuesday, August 7, 2012: 2:30 PM
Portland Blrm 257, Oregon Convention Center
Dustin Bronson1, Xin Song2, Michael Goulden3, Kenneth L. Clark4, Paul Bolstad5, Tilden Meyers6, Jiquan Chen7, Asko Noormets8, Danilo Dragoni9, David, Y. Hollinger10, J. William Munger11, Stephen Wofsy12, Timothy A. Martin13, Russell K. Monson14, Dennis D. Baldocchi15, Ankur R. Desai16, Eugenie Euskirchen17, William J. Massman18 and Brent Helliker2, (1)Biology, University of Pennsylvania, Philadelphia, (2)Department of Biology, University of Pennsylvania, Philadelphia, PA, (3)Department of Earth System Science, University of California, Irvine, Irvine, CA, (4)Silas Little Experimental Forest, USDA Forest Service, New Lisbon, NJ, (5)Department of Forest Resources, University of Minnesota, St. Paul, MN, (6)Atmospheric Tubulence and Diffusion Division, NOAA, Oak Ridge, TN, (7)Department of Environmental Sciences, University of Toledo, Toledo, OH 43606, Toledo, OH, (8)Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, (9)Nevada Division of Environmental Protection, Carson City, NV, (10)Northern Research Station, USDA Forest Service, Durham, NH, (11)School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, (12)Division of Engineering and Applied Science, Harvard University, Cambridge, MA, (13)School of Forest Resources and Conservation, University of Florida, Gainesville, FL, (14)Department of Ecology and Evolutionary Biology and Laboratory of Tree Ring Research, University of Arizona, Tucson, AZ, (15)Environmental Sciences, Policy, and Management, University of California, Berkeley, CA, (16)Atmospheric and Oceanic Sciences, University of Wisconsin, Madison, WI, (17)Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, (18)Rocky Mountain Research Station, U.S. Forest Service, Fort Collins, CO
Background/Question/Methods
We tested the hypothesis that the canopy temperature when weighted by growing season gross primary production (GPP) is approximately 21 °C, for a range of forest types from subtropical to boreal. We used stemwood tree cores from a selection of AmeriFlux sites to calculate a resolved canopy temperature using δ18O of the stemwood cellulose (Tcanδ). We also used data from the same AmeriFlux sites to calculate an air temperature value weighted by GPP (Tgpp).
Results/Conclusions
Our results confirm that values of Tcanδ are approximately 21 °C for a range of forested ecosystems, similar to previously published data. Our data also suggest that Tgpp could explain Tcanδ in temperate ecosystems. However, for ecosystems with extremely high or low mean annual temperature the difference between Tgpp and Tcanδ was as much as 8 °C. Prior eco-physiological studies have shown that plant canopy temperature can deviate substantially from air temperature either through convection for heating or transpiration for cooling. Therefore we employed infrared sensors to measure canopy temperature directly and will report these results as they compare to Tgpp, and Tcanδ.
