Carbon emissions from deforestation and forest fragmentation in the BrazilianAmazon

Abstract

Forest-fragmentation-related edge effects are one of the major causes of forest degradationin Amazonia and their spatio-temporal dynamics are highly influenced by annualdeforestation patterns. Rapid biomass collapse due to edge effects in forest fragments hasbeen reported in the Brazilian Amazon; however the collective impacts of this process onAmazonian carbon fluxes are poorly understood. We estimated biomass loss and carbonemissions from deforestation and forest fragmentation related to edge effects on the basis ofthe INPE (Brazilian National Space Research Institute) PRODES deforestation data andforest biomass volume data. The areas and ages of edge forests were calculated annuallyand the corresponding biomass loss and carbon emissions from these forest edges wereestimated using published rates of biomass decay and decomposition corresponding to theareas and ages of edge forests. Our analysis estimated carbon fluxes from deforestation(4195 Tg C) and edge forest (126–221 Tg C) for 2001–10 in the Brazilian Amazon.The impacts of varying rates of deforestation on regional forest fragmentationand carbon fluxes were also investigated, with the focus on two periods: 2001–5(high deforestation rates) and 2006–10 (low deforestation rates). Edge-releasedcarbon accounted for 2.6–4.5% of deforestation-related carbon emissions. However,the relative importance of carbon emissions from forest fragmentation increasedfrom 1.7–3.0% to 3.3–5.6% of the respective deforestation emissions between thetwo contrasting deforestation rates. Edge-related carbon fluxes are of increasingimportance for basin-wide carbon accounting, especially as regards ongoing reducingemissions from deforestation and forest degradation (REDD) efforts in BrazilianAmazonia.