Long-term (1990–2019) monitoring of forest cover changes in the humid tropics

Abstract

Accurate characterization of tropical moist forest changes is needed to support conservation policies and to quantify their contribution to global carbon fluxes more effectively. We document, at pantropical scale, the extent and changes (degradation, deforestation, and recovery) of these forests over the past three decades. We estimate that 17% of tropical moist forests have disappeared since 1990 with a remaining area of 1071 million hectares in 2019, from which 10% are degraded. Our study underlines the importance of the degradation process in these ecosystems, in particular, as a precursor of deforestation, and in the recent increase in tropical moist forest disturbances (natural and anthropogenic degradation or deforestation). Without a reduction of the present disturbance rates, undisturbed forests will disappear entirely in large tropical humid regions by 2050. Our study suggests that reinforcing actions are needed to prevent the initial degradation that leads to forest clearance in 45% of the cases.

The expansion of tree plantations across tropical biomes

“…Overall map accuracy (OA) was 90.6% (±0.1; table S6), with the largest error in the open class, and high mean class accuracies for plantation (93.1%) and natural regrowth (87.0%). This far exceeds the accuracy of a recent tropical moist forest product (18), which we estimate mapped just 60.2% of our reference plantation patches correctly (table s9). Latin America and Africa had the highest classi cation accuracies (table S6), with somewhat lower overall accuracy in Asia (89.7% OA) where misclassi cation of natural regrowth as plantation was highest.…”

“…Thus, tracking plantation expansion is essential to improve estimates of net global carbon sequestration and available agricultural area, and to assess the net impacts of progress towards restoration commitments. Using new data on tropical forest loss and regrowth (18), products like this one could be annually updated. Given current widespread international interest in tree planting, it is critical to monitor going forward how proposed expansions in plantation cover will affect remaining natural ecosystems.…”

“…These expert delineations cannot consistently detect changes in tree plantation area across regions because they focus on areas of intensive production and on a single time period. For example, although a recent study of tropical humid forest change ostensibly tracked plantation expansion over time, its delineation of tree plantations largely relied on single-date expert interpretation and the plantation map accuracy was not reported (18).…”

“…Despite the availability of national statistics to document these trends, consistent, spatially-explicit estimates of global increases in tree plantation area are lacking (13)(14)(15). Many efforts to map tree plantations rely on manual delineation of tree plantation boundaries from high-resolution satellite imagery and/or eld-collected data (1, 14,[16][17][18]. These expert delineations cannot consistently detect changes in tree plantation area across regions because they focus on areas of intensive production and on a single time period.…”

Crop Prices and Deforestation in the Tropics

“…Tropical deforestation is one of the main causes of recent global environmental changes. Recent assessments revealed that food systems are responsible for a third of global anthropogenic GHG emissions [1] and that 17% of tropical moist forests have disappeared since 1990, with a remaining area of about one billion hectares in 2019, from which 10% are degraded [2]. Deforestation threatens crucial ecosystem services, such as biodiversity richness, climate regulation, carbon storage, water supplies, and leads to more infectious diseases [3,4,5,6,7,8].…”