Forests around the world are becoming increasingly fragmented. While identifying where forest fragmentation has occurred seems like a fundamental ecological goal, attempts to do so often lead to mixed results. Many studies have examined forest fragmentation at a regional level, such as the tropics, or as a static pattern at one point in time. A more detailed understanding of how forests are fragmented over time – and at a global scale – could inform policy aimed at protecting and restoring forest fragments and their connectivity to each other.
Ma, J., Li, J., Wu, W. and Liu, J. 2023. Global forest fragmentation change from 2000 to 2020. Nature Communications 14: 3752.
A new study tackles this task by looking at forest fragmentation across the globe as a dynamic process. It creates an index of fragmentation and compares the change in this index from 2000 to 2020. This provides not only a comprehensive large scale snapshot of forest fragmentation, but also highlights the rates at which fragmentation has occurred over the past two decades.
The results of the analysis show that forest landscapes are still relatively intact in tropical regions that harbor some of the highest biodiversity in the world, such as the Amazon, the Democratic Republic of the Congo, Borneo, and New Guinea. However, those regions also saw the highest rates of fragmentation over the past two decades.
In contrast, the highest degree of forest fragmentation is found in many temperate and subtropical landscapes, such as eastern North America, southern Europe, and central and south China. Yet many of these forests have seen a decrease in fragmentation over time due to afforestation and protection efforts. Overall, 75% of the world’s forest landscapes experienced a decline in fragmentation over the two decades.
Human pressure helps explain both upward and downward trends in fragmentation over the two decades. Decreased fragmentation was mostly concentrated in the world’s most densely populated and economically developed regions, where government policies have helped to halt or reverse forest declines. In tropical regions, government policies and spreading human settlements also influence fragmentation, but often toward deforestation.
This dynamic measure of forest fragmentation may be more effective than static methods because it represents the process of forest fragmentation rather than spatial patterns alone. While some countries have made significant efforts toward preserving and connecting forests, everyone could benefit from a clearer understanding of how forest fragmentation has occurred over time across multiple regions. Quantifying the dynamics of forest fragmentation at a larger scale allows for better informed policy and aids in moving one step closer to greater sustainability of forest ecosystems.
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