Detecting and interpreting secondary forest on an old Amazonian frontier

Land uses that replace tropical forests are important determinants of terrestrial carbon storage and biodiversity. This includes secondary forest growth after deforestation, which has been integrated into the REDD+ (Reducing Emissions from Deforestation and Forest Degradation) concept as a means to enhance current forest carbon stocks. Incorporating secondary forest into climate change mitigation efforts requires both accurate measurements and a means to target interventions to achieve additionality. We demonstrate how remote sensing and household survey data can be combined to meet these requirements in ‘old frontiers’ of the Brazilian Amazon and introduce the idea that annual land-cover transitions − measured at the pixel level and over time − can serve as leading indicators of secondary forest regrowth. The patterns we observe are consistent with the suggested tension between equity and additionality in REDD+: the poorest households on the poorest quality lots already allow forest regeneration. Policy interventions to encourage regeneration are likely to have the greatest additional impact on higher quality lots owned by better capitalized households.