HR: 10:20h
AN: B41E-01 INVITED     [PDF]
TI: Selective Logging Disturbance And Isotopic Composition Of Repired CO2 In Western Amazonia, Brazil
AU: * Ometto, J P
EM: ometto@biology.utah.edu
AF: Centro de Energia Nuclear na Agricultura/USP, Av. Centenario, 303, Piracicaba, SP 13416-000 Brazil
AU: * Ometto, J P
EM: ometto@biology.utah.edu
AF: University Of Utah, Department of Biology 257 South 1400 East, Salt Lake City, UT 84112 United States
AU: Martinelli, L A
EM: martinelli@cena.usp.br
AF: Centro de Energia Nuclear na Agricultura/USP, Av. Centenario, 303, Piracicaba, SP 13416-000 Brazil
AU: Ehleringer, J R
EM: ehleringer@biology.utah.edu
AF: Carnegie Institution of Washington, Department of Global Ecology 260 Panama St., Stanford, CA 94305 United States
AU: Berry, J
EM: joeberry@globalecology.stanford.edu
AF: Carnegie Institution of Washington, Department of Global Ecology 260 Panama St., Stanford, CA 94305 United States
AU: Miller, S
EM: sdmiller@uci.edu
AF: University of California, Dept. of Earth System Science, Irvine, CA 92697-3100 United States
AU: Goulden, M
EM: mgoulden@uci.edu
AF: University of California, Dept. of Earth System Science, Irvine, CA 92697-3100 United States
AB: Understanding the controls of gas exchange in primary and disturbed forests within the Amazon Basin is central to understanding the global carbon cycle, since tropical forests account for 40% of the carbon stored globally in terrestrial biomass. Stable isotope ratio analyses (13C, 18O) of atmospheric CO2 provide useful information regarding the balance between photosynthetic carbon gain and respiratory carbon loss in rainforest ecosystems and of the stomatal constraints on photosynthetic gas exchange. One useful isotopic parameter we have measured is the carbon isotope ratio of all respiration emerging from the ecosystem (del13Cr). Our recent observations suggest a direct relationship between logging activities and del13Cr values in these forests. Logging activities at the LBA site in Santarem, Para, began with the removal of lianas before the dry season and afterward selective logging. This logging activity opened the forest and resulted in a 4per mil shift in del13CR. During the following wet season (2002/2003), eddy covariance measurements at the logged site reported increased ecosystem gas exchange. Coincident with this increase in net ecosystem exchange, we observed a decrease in del13CR consistent with a decreased stomatal limitation on photosynthetic gas exchange in the logged forest.
DE: 0400 Biogeosciences
DE: 4805 Biogeochemical cycles (1615)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting