Emissions from forest edges offset half of Brazilian Amazon REDD+ results
Abstract
Tropical forests provide essential ecosystem services, including carbon storage, biodiversity, and climate regulation. However, the extent of these forests declined by 10% from 1990 to 2015 due to deforestation. In the Amazon, deforestation leads to large-scale forest fragmentation that increases the extent of forest edges. Forest edges impacted by changes in the forest microclimate such as humidity, temperature, and wind, cause loss of carbon stocks by increasing tree mortality and spreading fires.
During the 2006-2019 period, Brazil reported an emission reduction of 7,413 Tg CO2eq (530±167 Tg CO2eq y-1) to UNFCCC due to reducing deforestation (REDD+). This estimate does not include emissions from forest edges. Here, we hypothesize that edge-effect committed emissions can counteract the carbon credits developed from avoided deforestation. To test our hypothesis, we calculate net emissions by estimating carbon loss at forest edges using remote sensing data and carbon gain from secondary forest regeneration in the Amazon. Our results show that forest edges emitted 3,602 Tg CO2eq (257±66 Tg CO2eq y-1) between 2006 and 2019, or about 49% of Brazilian Amazon REDD+ results in the same period. Furthermore, secondary forests' uptake during this period (17±11 Tg CO2eq y-1) was insufficient to compensate (7±5 % y-1) for the annual emissions from edge effects. We also highlight that in 2016 and 2019 alone, emissions from forest edges compromised the full REDD+ carbon credits, even with secondary forest uptake. This scenario can be explained mainly by an increase in deforestation in the Brazilian Amazon since 2013, caused by changes in the Brazilian Forest Code in 2012 and the environmental setbacks in Brazil intensified in the last years. Our results show that edge effects can compromise a national REDD+ strategy focused exclusively on reducing emissions from deforestation. Brazilian decision-makers, therefore, should take urgent action to stop the climb of deforestation, and develop a fire-free policy and fire use substitution program for the Amazon. We recommend that emissions from edge effects be quantified and reported explicitly with emissions from deforestation, allowing better quantification of the atmosphere's greenhouse gas fluxes.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.B51B..03A