Non-COsub(2) volatile carbon emissions and net ecosystem exchange in Amazonia

Abstract

At present, the global CO, budget requires the addition of a large, unidentified terrestrial 8ink in order to balance. After peatlands, forests contain the largest terrestrial reservoirs of carbon. Landuse changes in forested areas, therefore, represent a significant potential impact on the global carbon cycle. The net exchange of CO, between ecosystems and the atmosphere is a measure of the net ecosystem exchange of carbon (NEE). The net flux of CO; should be into young, rapidly growing forests; out of areas of recently cleared forest areas (as the organic matter decomposes); but near zero for mature or primary forests. The estimation of the nct carbon exchange is complicated by the potential for missing a significant exchange of non-CO, carbon. Living and dead organic matter emit a variety of volatile organic compounds (VOCs), including carbon monoxide, methane, isoprene, monoterpenes, methanol, acetone, acetaldehyde, formaldehyde, many VOCs related to damage of plant tissue, etc. We have measured several of these non-CO, VOC emissions at the landscape level in various states in Amazdnia, including Amazdnas (near Balbina, primary and secondary forest), Rondonia (recently cleared forest and pasture as well as primary forest) and Para (near Santarém, primary and secondary forest). The atmospheric concentration profiles of these VOC emissions were used to estimate hourly and daily emissions; a biogenic emission model was used to extrapolate these emissions to na annual flux. This annual emission estimate was then used to gauge the importance of non-CO, VOC emissions to NEE in Amazonia,