Benchmark maps of 33 years of secondary forest age for Brazil

Abstract

The restoration and reforestation of 12 million hectares of forests by 2030 are amongst the leading mitigation strategies for reducing carbon emissions within the Brazilian Nationally Determined Contribution targets assumed under the Paris Agreement. Understanding the dynamics of forest cover, which steeply decreased between 1985 and 2018 throughout Brazil, is essential for estimating the global carbon balance and quantifying the provision of ecosystem services. To know the long-term increment, extent, and age of secondary forests is crucial; however, these variables are yet poorly quantified. Here we developed a 30-m spatial resolution dataset of the annual increment, extent, and age of secondary forests for Brazil over the 1986-2018 period. Land-use and land-cover maps from MapBiomas Project (Collection 4.1) were used as input data for our algorithm, implemented in the Google Earth Engine platform. This dataset provides critical spatially explicit information for supporting carbon emissions reduction, biodiversity, and restoration policies, enabling environmental science applications, territorial planning, and subsidizing environmental law enforcement.

Fig. 1

Forest cover of Brazil. In the main map, black lines represent the Brazilian biomes: 1. Amazon; 2. Caatinga; 3. Cerrado; 4. Atlantic Forest; 5. Pampa; 6. Pantanal. Source: land-use and land-cover map of 2018 from the MapBiomas Project (http://mapbiomas.org).

Fig. 2

Workflow of the proposed method.

Fig. 3

Conceptual model of the approach used to calculate the age of secondary forests throughout the Brazilian territory.

Fig. 4

(a) Scatter-plot for the relationship between the proportion of the secondary forest within the 10 by 10 km cells in the two datasets. The dashed blue line is the 1:1 line; the red line is the average regression from the bootstrap approach with 10,000 interactions; the dashed red lines are regressions using the standard deviation values of the equation parameters. All p-values from the 10,000 bootstrap interactions were lower than 0.001. (b) Jitter-plot for the proportion of the secondary forest within the 10 by 10 km cells. The red dot is the mean, and the red vertical line the standard deviation.

Fig. 5

(a) Map of Brazil with secondary forests identified using the process outlined in the text. The detailed map on the left shows the age of secondary forests in the Amazon, while the detailed map on the right shows the age of secondary forests in the Atlantic Forest. (b–g) Histogram of secondary forest age for each Brazilian biome. The dashed black lines represent the age threshold where more than 50% of secondary forests are accumulated.