Carbon and nutrient transfers following selective logging in the Amazon: Combining remote sensing and allometry.
Lydia
Pauline
Olander, Department of Global Ecology, Carnegie Institution of Washington, lolander@globalecology.stanford.edu
Gregory
Paul
Asner, Department of Global Ecology, Carnegie Institution of Washington, gpa@stanford.edu
Mercedes
Maria Cunha
Bustamante, Universidade de Brasilia, mercedes@unb.br
Until recently it was thought that remotely sensed data were not sufficient to detect and quantify selective logging damage in tropical forests. New spectral mixture analysis of multispectral data has successfully detected selective logging in the Amazon, and an equation has been developed to determine forest gap fraction in logged areas. Logging plots at Cauaxi and Tapajos in the eastern basin, are captured in Advanced Land Imager or Landsat scenes collected within a year after the logging event. Using remote sensing combined with literature data we estimate how selective logging changes the spatial distribution and quantities of carbon and nutrients.
The total increase in forest gap after logging is around 5% in reduced impact logging blocks and around 20% in conventional logging. Combining this measure of the aerial extent of canopy missing with allometric relationships and data on nutrient concentration for foliage and woody parts, we estimate the total amount of carbon and nutrients transferred from the canopy to the forest floor during a logging event minus those removed as harvest to be approximately 21,000 kgC, 350 kgN, 26 kgP, 160kgK, 350kgCa, and 80kgMg per hectare in the logging areas. This nutrient flush causes significant changes in carbon and nutrients in the top 10cm of soil. Since forest gap corresponds with coarse woody debris, we use the spatial distribution of forest gap after logging to produce an image of estimated spatial distribution of debris. Our results suggest that remote sensing can provide valuable information about the spatial characteristics and quantity of carbon and nutrients altered by selective logging.
Submetido por Lydia Pauline Olander em 24-MAR-2004
Tema Científico do LBA: LC (Mudanças dos Usos da Terra e da Vegetação)