Synthesis and Integration of Ecological Research within the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) and Science Support for LBA-ECO
Michael M. Keller USDA Forest Service (US-PI)
1. Extend a four year time-series of soil-atmosphere carbon dioxide flux using an automated chamber system at the Tapajos National Forest in order to gain greater understanding of seasonal and interannual variability of the forest carbon balance at that site.
2. Quantify the carbon release from selective logging for the entire Brazilian Amazon during the period 1999 through 2002 using remote sensing products to drive ecosystem models.
3. Lead synthesis and integration of LBA -ECO studies as LBA-ECO Project Scientist.
During 2005, we propose to continue our measurements of soil-atmosphere CO2 flux at the Tapajos National Forest as a complement to ongoing studies of carbon cycling there. Assuming that we maintain our record of nearly 80% data recovery, we expect to collect about 28,000 fluxes. Changes in ecosystem respiration had a greater effect on the seasonal pattern of net ecosystem carbon exchange (NEE) than changes in primary productivity. Existing models predict seasonality of tropical forest NEE opposite to that observed. Our continued data collection will be used to calibrate and/or validate new models of soil-atmosphere CO2 flux.
We plan to use two approaches to estimate carbon budgets for logged forests in the Brazilian Amazon. Our first approach is to isolate the two dominant changes in ecosystem carbon balance following logging, the increase in respiration from newly created coarse woody debris and the decrease in photosynthesis owing to reduced canopy cover. Forest structural changes are being estimated based upon a spectral mixture analysis of Landsat 7 ETM+ data for six Brazilian Amazon states over the period 1999-2002 that account for 95% of logging in the Brazilian Amazon. The changes will be translated into estimates of coarse woody debris (CWD) generation based on extensive field studies already completed. Estimates of heterotrophic respiration from CWD will be based on published studies and our own field measurements of CWD respiration during Phase II of LBA-ECO. Changes in net primary production (NPP) will be estimated with the use of a production efficiency model approach. Our second approach will be to implement the CASA model over the same six state area. CASA is also based on production efficiency model. The advantage to this approach is the wider range of potential changes that may be considered. The disadvantage is the greater complexity of the model and the uncertainties related to its parameterization for logged forests. Both of these approaches will yield carbon budgets for the same six state area. In each case, the real logging scenario will be compared to a background forest scenario, either using 1999 as a baseline year or a synthetic baseline of undisturbed forest.
During the integration and synthesis phase of LBA-ECO, the role of the Project Scientist is to unite and support the efforts of the Science Team selected by NASA. This proposal discusses the accomplishments of the current Project Scientist thereby indicating why he is highly qualified to continue his present role.