Forest Fragmentation, Orangutans

Forest fragmentation has come up more than once, so it’s worth taking a closer look. The more I move through the forest, the more I notice its lack of continuity. What once stretched uninterrupted now appears broken in places, separated by roads, clearings, or development such as plantations, creating smaller, isolated patches of forest.

This is what fragmentation looks like. The forest still exists, but it is no longer connected, its size reduced, and its structure changed. With more breaks comes more edge, and these edges behave differently, with changes that can extend deep into the forest. They are hotter, drier, and more exposed to wind and light, altering the conditions for everything that lives within them. Interior species begin to struggle, while more adaptable or invasive species move in. Trees near the edges are also more likely to die or fall.

Up in the canopy, the impact becomes even clearer. For species like orangutans, the forest isn’t just trees; it’s a connected pathway. When those links are broken, even small gaps can become real barriers. Descending to the ground brings risks, exposing them to predators such as large reptiles and clouded leopards, to human activity, including poaching, and to unfamiliar terrain they are not adapted to navigate. The ground is not their natural environment, so what looks like a short distance to us can limit where they can go. As a result, groups can become separated, leading to isolation, which in turn reduces genetic diversity. With smaller, isolated groups, there are fewer opportunities to mix with others, weakening their ability to adapt and increasing the risk of long-term decline.

Not all fragmentation is obvious. In some cases, the forest can still appear intact, especially when viewed from above. On the ground, however, the story is different. Selective logging, narrow roads, and even pipelines can break up the landscape, disrupting movement without fully clearing the forest. What remains may look continuous, but it is already broken in ways that affect how animals move and how the ecosystem functions.

In some ways, fragmentation can be more damaging than outright deforestation. Losing a large area of forest in a single block is significant, but breaking an entire landscape into smaller, disconnected pieces can affect more species overall. It’s not just about how much forest remains, but how well it stays connected.

Across Borneo, over 30% of forest cover has been lost since the 1970s, and much of what remains is a mosaic of fragmented patches, with lowland forests the most affected.

Conservationists are working to reconnect fragmented forests by creating wildlife corridors and restoring narrow strips of forest that act as natural bridges. In some areas, efforts also focus on limiting road expansion and protecting what remains of any continuous forest. Though still a work in progress, results are beginning to show. In northern Tabin, restored corridors have allowed canopies to reconnect, with gibbons returning, while in the Kinabatangan region, orangutans have been seen using trees planted just a decade earlier. These examples show that even small connections can make a difference, with restored areas recovering faster than expected through simple methods such as clearing competing vines to help young trees grow.