Multitemporal Analysis of Tree Cover, Fragmentation, Connectivity, and Climate in Coastal Watersheds of Oaxaca, Mexico

Abstract

The synergistic interaction between landscape fragmentation and climate change poses a critical threat to tropical forests. However, the long-term dynamics of these coupled pressures have been little explored. This study analyzes half a century (1979–2023) of changes in landscape structure and climate across five coastal watersheds in Oaxaca, Mexico a region of high biological and socio-economic diversity. Using multitemporal satellite imagery (Corona, Orthophotos, RapidEye and Planet), we quantified the trajectories of tree cover, fragmentation (Largest Patch Index, LPI; Simpson’s Diversity Index, SIDI), and connectivity (Probability of Connectivity Index, PC); and contrasted these with temperature and precipitation trends. Our results reveal that during the period 1979–2010, there was a slight increase in tree cover accompanied by positive landscape metrics, whereas in the period 2010–2023 a loss of tree cover was observed. Nonetheless, overall, between 1979 and 2023, the analysis indicates a net gain of 59,725 ha of tree cover, a reduction in fragmentation (LPI increased by 26.33% and SIDI decreased by 0.23), and an improvement in connectivity (PC increased by 0.35). During the same period, the average annual temperature increased by 2.3 °C, and precipitation decreased by 219 mm annually. The study concludes that the system is undergoing a transition from a spatial configuration limitation to a climate-induced habitat quality limitation.