Spatiotemporal patterns of forest fragmentation along the border region of Yunnan Province in Southwest China from 1985 to 2022

Forest is a critical habitat for safeguarding ecosystem integrity and biodiversity in border regions. However, human pressure has increased in these regions due to economic globalization, and forest fragmentation has become one of the main threats to transboundary species. In this study, the Yunnan Border Region (YBR) in Southwest China, which connects China, Myanmar, Laos, and Vietnam, was selected to explore the spatiotemporal patterns, driving forces, and country differences in forest fragmentation over recent decades, using forest area density analysis and a nonlinear response model. The results showed that: (1) On average, forests accounted for 71.82 % of the YBR, with a total net loss of 10318.76 km 2 and most forest gain occurred in the Chinese part from 1985 to 2022. (2) In general, the level of forest fragmentation was low in the YBR but increased during the study period. Among the different subregions, forest fragmentation was lowest in the Myanmar part but highest in the Vietnam part, while the rate of increase in forest fragmentation was fastest in Myanmar but slowest in Vietnam. Spatially, the gravity centers of high fragmentation classes shifted from east to west, and temporally, those of forest fragmentation from high to low levels gradually shifted from the southeast to the northwest. (3) Human footprint was the main driver of forest fragmentation, and the relative contributions of elevation, slope, and wildfire varied across countries and over time in the YBR. This study demonstrates that forest fragmentation has become an unignorable issue under intensified human pressure in the YBR, and the obvious differences in it among adjacent countries call for transboundary collaboration to conserve forest ecosystems and biodiversity in border regions. • There is a net loss of forest in the YBR, with the area of 10318.76 km 2 . • The forest fragmentation level was low but has intensified in the YBR. • Human footprint is the main driver of forest fragmentation in the YBR. • There are significant country differences in forest fragmentation in the YBR.