Beyond deforestation: Differences in long-term regrowth dynamics across land use regimes in southern Amazonia

Abstract

The loss of tropical forests threatens a broad range of ecosystem services. Particularly, tropical deforestation is a major driver of biodiversity decline and substantial carbon emissions. Regrowth of secondary vegetation may help to restore habitat for many threatened species and improve ecosystem services that deteriorated due to deforestation. However, spatial-temporal patterns of regrowing secondary vegetation in the tropics remain weakly understood. We therefore analyze regrowth dynamics across two different land use systems in southern Amazonia: the extensive pastoralism in Pará and the capital-intensive agriculture in Mato Grosso. Both systems are connected by the BR-163 highway, which represents a major axis of deforestation and agricultural development in the Brazilian Amazon since decades. We used a 29 year time series of Landsat images to extract regrowth extent, duration, lag time between deforestation and regrowth, and frequency of regrowth cycles. Our results reached an overall accuracy of 89% and showed regrowth on up to 50% of the deforested area in Pará and a maximum of 25% in Mato Grosso. In both states, annual regrowth rates drastically dropped after 1996, which coincided with socioeconomic transformations and drought events. The majority of regrowth was concentrated within 60m distance to forest edges and cleared again after an average of 5 years. Our approach bears great potential for mapping post deforestation regrowth dynamics within and beyond the Brazilian Amazon based on long-term and freely accessible remote sensing data collections, such as the Landsat and the forthcoming Sentinel-2 archives.

Fostering natural forest regeneration on former agricultural land through economic and policy interventions

“…Extensive areas of natural regeneration in Amazonia are often observed in areas close to large remnant patches of forest and low intensity of land use (Jakovac et al 2015, Lennox et al 2018. Along a 1000 km stretch of the BR-163 highway, natural regeneration adjacent to forests contributed to 85% and 70% in Pará and Mato Grosso, respectively, of all forest regrowth detected between 1985 and 2012 (Müller et al 2016). Absolute rates of natural regeneration were strongly dependent on the overall amount of deforested area, with higher rates in Pará (maximum of 50% of deforested area) on former pastures with lower management intensity compared to Mato Grosso (maximum of 25% of deforested area) where capitalintensive cropland and pasture systems dominate (Müller et al 2016).…”

“…Along a 1000 km stretch of the BR-163 highway, natural regeneration adjacent to forests contributed to 85% and 70% in Pará and Mato Grosso, respectively, of all forest regrowth detected between 1985 and 2012 (Müller et al 2016). Absolute rates of natural regeneration were strongly dependent on the overall amount of deforested area, with higher rates in Pará (maximum of 50% of deforested area) on former pastures with lower management intensity compared to Mato Grosso (maximum of 25% of deforested area) where capitalintensive cropland and pasture systems dominate (Müller et al 2016). In the Brazilian Amazon, Conrado da Cruz et al (2020) identified 405 forest restoration projects in 191 municipalities between 1950 and 2017, forest restoration techniques used in descending order of importance were seedling planting, agroforestry systems, assisted natural regeneration, and natural regeneration.…”

What Drives Intensification of Land Use at Agricultural Frontiers in the Brazilian Amazon? Evidence from a Decision Game

“…These municipalities were selected due to their proximity to the BR-163 highway and their key role in developing the regional agricultural sector. Despite the overall success of Brazil's strategy to reduce Amazon deforestation, forest loss began to rise again after 2012, particularly in municipalities located along the BR-163 [36,37]. A number of studies suggested knowledge gaps in our understanding of how conservation policy incentives affect land-use decisions over time and under changing economic conditions [38][39][40][41].…”

Dinâmica socioeconômica de duas comunidades rurais no Assentamento Moju I e II, Amazônia Paraense

“…Recentemente esta região oeste do Pará incorpora-se à expansão do agronegócio, estimulando uma nova frente migratória de produtores capitalizados, principalmente da região Sul do país (CORTÊS; D'ANTONA, 2016). Müller et al (2016) mencionam neste contexto o avanço do desmatamento nesta região, caracterizando o uso da terra mediante a pecuária extensiva.…”