Selective Logging Effects on Carbon Budgets at Three Sites in the Brazilian Amazon
Michael
M.
Keller, USDA Forest Service, International Institute of Tropical Forestry, michael.keller@unh.edu
(Presenting)
Michael
William
Palace, University of New Hampshire, palace@kaos.sr.unh.edu
José
Natalino Macedo
Silva, EMBRAPA, Amazônia Oriental, natalino@cpatu.embrapa.br
Gregory
Paul
Asner, Carnegie Institution of Washington, Stanford University, gpa@stanford.edu
Single tree selection is the predominant approach to logging in the Brazilian Amazon today. While removal of logs (usually less than 40 m-3 ha-1 on a first entry) off-site has a minor effect on site carbon stocks, collateral damage caused by felling, skidding, and road building results in signficant mortality and canopy opening. Reduction of canopy leaf area should reduce productivity while the increase in necromass should augment ecosystem respiration. We aim to quantify these effects in both conventional (CL) and reduced impact (RIL) harvest management at sites in the municipalities of Paragominas and Santarem in Para State and in Juruena in Mato Grosso state. Canopy gap fraction (Licor, LAI-2000) and both standing and fallen coarse woody debris (line intercept sampling) were measured at logged and unlogged sites. For logging intensities in the range of 20 to 30 m-3 ha-1, CL and RIL increased canopy gap fraction to approximately 20% and 10% compared to approximately 3% gap fraction at undisturbed forest sites. Logging also greatly increased necromass stocks. For example,at the sites in Paragominas, necromass stocks increased by 95% and 35% for CL and RIL over a background of about 28 Mg-C ha-1 in undisturbed forest. We modeled the effects on carbon flux using stand table models and simple compartment models to estimate post-site carbon balance. Based on simple extrapolation from our limited sites, we estimate that logging leads to a net loss of at least 30 Tg-C y-1 from the Brazilian Amazon.
Submetido por Michael M. Keller em 18-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)