Rapid and Intense Declines of Forest Connectivity in the Amazon Arc of Deforestation Over Four Decades
Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine
ABSTRACT The Amazon Arc of Deforestation is facing a silent decline in ecological functionality. Using four decades of high‐resolution land cover data, we reveal a dramatic decline in functional connectivity across deforested areas in the Brazilian Amazon. Analyzing 40 targeted large‐scale forest landscapes across Pará, Mato Grosso, and Rondônia, we quantified connectivity for key ecological processes—seed dispersal, pollen dispersal, and gap‐crossing capacity of animals—using graph theory metrics. Between 1990 and 2020, the connectivity dropped by up to 50% in highly deforested regions, even when accounting for stepping‐stones. Simultaneously, spatial modularity increased in nearly all study regions, in some by more than 25%, reflecting a more compartmentalized landscape structure. Forest fragment distances rose, and mean patch area fell sharply, compromising dispersal and potentially gene flow. Our results suggest a potential breakdown of spatial connectivity within the targeted zones of the Amazonian forests, except in the Western Pará region, where higher connectivity and lower modularity still prevail. Without urgent connectivity‐enhancing strategies, even remaining forest patches may become functionally isolated, threatening the maintenance of biodiversity. Deforestation increased landscape fragmentation between 1990 and 2020. Ecological distance thresholds constrain gap crossing, seed dispersal, and pollen dispersal. Functional connectivity declined over time, while la
Abstract
ABSTRACT The Amazon Arc of Deforestation is facing a silent decline in ecological functionality. Using four decades of high‐resolution land cover data, we reveal a dramatic decline in functional connectivity across deforested areas in the Brazilian Amazon. Analyzing 40 targeted large‐scale forest landscapes across Pará, Mato Grosso, and Rondônia, we quantified connectivity for key ecological processes—seed dispersal, pollen dispersal, and gap‐crossing capacity of animals—using graph theory metrics. Between 1990 and 2020, the connectivity dropped by up to 50% in highly deforested regions, even when accounting for stepping‐stones. Simultaneously, spatial modularity increased in nearly all study regions, in some by more than 25%, reflecting a more compartmentalized landscape structure. Forest fragment distances rose, and mean patch area fell sharply, compromising dispersal and potentially gene flow. Our results suggest a potential breakdown of spatial connectivity within the targeted zones of the Amazonian forests, except in the Western Pará region, where higher connectivity and lower modularity still prevail. Without urgent connectivity‐enhancing strategies, even remaining forest patches may become functionally isolated, threatening the maintenance of biodiversity. Deforestation increased landscape fragmentation between 1990 and 2020. Ecological distance thresholds constrain gap crossing, seed dispersal, and pollen dispersal. Functional connectivity declined over time, while landscape modularity increased. graphical