In the Brazilian Amazon, secondary regrowing forests comprise about 21% of previously deforested areas. They can accumulate carbon very rapidly, thereby providing a key pathway to reduce net carbon emissions and mitigate climate change. However, a historical lack of spatio-temporal data on secondary forest area has precluded evaluation of their large-scale change dynamics.  

Now researchers, from University of Leeds, Brazilian National Institute for Space Research (INPE) and Brazilian Agricultural Research Corporation (EMBRAPA), have conducted the first estimates of secondary forest clearings for the Brazilian Amazon over 14 years based on the TERRACLASS post-deforestation land use products.  

Our study, published in Nature Sustainability, has found that secondary forest cutting has increased sharply across the entire Brazilian Amazon (~187% increase between 2008-2014), despite the stabilisation of primary forest deforestation over this period. The proportion of total deforestation accounted for by secondary forests rose from 37% in 2000 to 72% in 2014. 

The study suggests that secondary forest clearing has eased deforestation pressure on primary forests, providing a buffer that has stalled deforestation of primary forests. However, the strength of this buffer depends on the area of secondary forest available. The limited legal protection on secondary forests would likely lead to a decrease of the accessible area of secondary forests, with the potential to increase the pressure on primary forest deforestation. 

Brazil has committed to restore 120,000 km^2 of forest land by 2030 as part of its Nationally Determined Contribution for the Paris Agreement. A cost-effective way to do this would be to allow part of its existing Amazonian secondary forest area to recover naturally.

However, managing secondary forests sustainably to maximize their conservation value, while not intensifying pressure on primary forests, requires an integrated strategy that includes active monitoring of secondary forests in Amazonia and strengthening of their governance in Brazilian law.