Congratulations to Hangkai You and collaborators on their new paper, “Episodic changes in global forest edges in the 21st century,” published in Nature Communications.
Forest edges are important ecological zones that influence biodiversity, microclimate, carbon cycling, and ecosystem vulnerability. Although about 70% of the world’s forests occur within 1 km of an edge, how forest edges have changed globally over time has remained poorly understood.
In this study, Hangkai and colleagues developed high-resolution global maps of forest edges from 2000 to 2020. They found that total global forest-edge length decreased by approximately 24 million km, or 7%, over the study period. Importantly, the changes were highly episodic and varied substantially across regions and biomes.
One particularly interesting period was 2015–2020, when global forest-edge length declined even as total forest area increased slightly. The analysis shows that this pattern reflected contrasting processes: forest patches increasingly merged in temperate and boreal regions, while fragmentation continued in many tropical forests. Some countries, including Laos, Liberia, India, and China, instead experienced increasing forest-edge length associated with the creation of new forest patches.
The study further shows that many of these changes correspond closely with land-management and policy shifts, including logging restrictions, agricultural expansion, and reforestation programs. This illustrates why changes in forest area alone cannot fully describe how forest landscapes are changing: the spatial configuration of forests—and therefore the amount and location of forest edge—can change substantially even when total forest area changes little.
The work provides a new global perspective on forest fragmentation and landscape dynamics and highlights the need to consider forest configuration alongside forest area when evaluating biodiversity conservation, carbon storage, and land-management outcomes.
The study was led by Hangkai You of the UW–Madison Department of Forest and Wildlife Ecology, with coauthors Fujiang Ji, Taejin Park, Volker C. Radeloff, George Hurtt, Minhui Jiang, and Min Chen. The paper was published in Nature Communications on October 5, 2026.
Read the paper:
You, H., Ji, F., Park, T., et al. (2026). Episodic changes in global forest edges in the 21st century. Nature Communications.