The list of threats that wildlife faces seems to be never ending. From climate change to invasive species there are so many challenges that conservation is trying to overcome. But there is one issue that occurs slowly and silently in almost all countries across the world - forest fragmentation.
Forest fragmentation occurs when a forest or similar habitat is broken into smaller patches. This can sometimes be natural, via an event like a volcanic explosion, but now it is more often through human activity. This can be through roads, the expansion of agricultural land, housing or any other sort of anthropological activity that creates a breakage in the landscape. The breaking apart of continuous habitat is creating ‘islands’ causing major physical and biological changes to the habitat.
One of the biggest issues caused by forest fragmentation is the altering of the interior-edge ratio. Imagine we had a very natural habitat that was unusually useful for maths - a 6x6 square. The perimeter of this habitat would be 24km while the area would be 36km squared. Therefore we have an interior edge ratio of 36:24. If this habitat was to be halved, by an unusually thin road, we would have a 3x3 square leading us to an interior edge ratio of 9:12 - results in much more edge than interior habitat. There are many reasons why this matters, as more edge habitat results in:
Increased light levels
Increased wind speeds
Lower humidity
Increased temperature
Increased risk of forest fires
All of these factors greatly impact the lives of the plants and animals that live in the habitat. Many species that are threatened with extinction have very specific habitat requirements and so even a slight change can impact their survival. It is important to mention that some species thrive in edge habitats, for example deer or owls.
When a forest is fragmented it restricts the movement of species and in many instances forces them to move through human settlements and could get them directly involved in human-wildlife conflict. This can be catastrophic for both the animals and the people whose livelihoods or even lives can be lost. But being cut off also has another problem - inbreeding. Animals left behind in the habitat island cannot find genetically diverse mates and over time this can create a bottleneck effect whereby unfavourable genetics become more common in the population. This leads them to struggle to adapt to change and can lead to local extinctions.
There have been attempts to reduce the impacts of forest fragmentation or even to reverse it altogether. One of the world biggest conservation projects is the creation of a tiger corridor across Asia, including in Northern India, Thailand and Bhutan. The aim is to connect fragments of tiger habitat to allow them to traverse for mating or foraging, while also keeping them from venturing into densely human populated areas. There are also artificial solutions to fragmentation including wildlife bridges over roads, or underground tunnels beneath them. These can be physical bridges or canopy bridges, where the trees reach over the road to allow animals like macaques to cross them safely.
We need to think big when it comes to forest fragmentation. Over 70% of the worlds forest is now within 1km of a forest edge and this has major impacts for the wildlife and plants that make their homes in these habitats. But, there is hope, as millions of people work to conserve endangered species, even if it is just in our back gardens. So help that toad cross the road or leave that hedgerow as it is. Even if it does mean you get non-stop handymen coming to your door letting you know that your garden plants are untidy and they can fix that. At least the insects and birds appreciate it!
While wildlife conservation projects are key to combatting the effects of forest fragmentation they cannot be at the expense of indigenous people. There have been many examples of indigenous peoples across the world being treated appalling for the sake of conservation efforts, including being evicted from their land to allow the construction or protection of wildlife corridors. This is unacceptable and indigenous and local people must be involved at all stages of conservation projects, from inception to implementation, if the projects are to work for both humans and animals.