The road you travel on every day may take you to the places you need to go, but chances are it fragmented a habitat by cutting through it.
Habitat fragmentation creates isolated patches of landscape, which can have harmful effects on biodiversity.
What is Habitat Fragmentation
Imagine that one day you are driving to work, and suddenly there is a new wall in the road blocking you from going any further. You know what is on the other side – your office, the grocery store, your friends and family. However, you are now completely disconnected from these important resources, and going about your life normally doesn’t really seem like an option any longer.
Though you depend on the road to travel to the places you need to go, that road itself may have cut through a habitat that was once contiguous.
Animals that live in these habitats are now in the same situation that you were when your road was blocked because their habitat has become fragmented. Fragmented habitats are habitats that were once contiguous but are now separated into smaller, isolated areas.
Causes of Fragmentation
Habitat fragmentation usually occurs because of human activities such as new roads, parking lots and housing developments. Organisms need their specific habitat for survival, and fragmentation is a leading threat to many terrestrial animals. Not only are these animals separated from the resources they depend on, but they now have to travel across dangerous areas, such as roads, to reach those resources.Habitat fragmentation from human activities is not limited to urban areas. Logging is a major cause of habitat fragmentation in forests.
Logging creates clear-cut, open ground areas that were once protected by the cover of trees. Logging roads that are built for the logging trucks to travel on can also be cut through forests, disrupting the habitat.Habitats may also become fragmented by natural processes. Rivers serve as natural pathways for both terrestrial and aquatic animals. If the river floods, it may make passage across it by terrestrial animals impossible. On the other hand, aquatic animals that depend on the river to move between two different water bodies will not be able to travel from one place to another if the river dries up.
Effects of Fragmentation
Fragmented habitats may be subject to the edge effect. The edges of habitats are important parts of the landscape and are so unique that they have their own sets of physical conditions and communities of organisms. When habitats become fragmented, their edges often become more abrupt and transition less smoothly than they would naturally.Edges usually have less diversity and are dominated by a small number of species specially adapted to those areas.
When more edges are created, the species inhabiting edges expand into areas that they wouldn’t normally be found. This creates new competition for the species native to the fragmented habitats, and this can have detrimental effects on those original species.Also, since habitat fragmentation breaks the original habitat into smaller, isolated patches, movement between these patches can become dangerous.
This is especially true if animals now have to cross something like a busy road. To make passage safer, wildlife corridors may be created. Wildlife corridors are a thin strip of habitat linking larger patches of wild habitat.
They are like roads for animals, providing a safe way to get from one place to another. Wildlife corridors are often constructed as ‘land bridges’ across busy roads, or tunnels underground.In some situations, habitat fragmentation may lead to species becoming threatened or endangered. Smaller fragments of habitat cannot support as many species and individuals as larger habitats, so the size of the new fragmented patches will dictate the continued survival of those species.Habitat fragmentation also creates smaller, isolated populations. Smaller populations are more susceptible to resource competition, disease and natural disasters and are, therefore, more vulnerable to extinction.
Small changes in climate, predation and resource availability would normally be less noticeable to a larger population, but can have drastic effects on smaller, fragmented ones.
Let’s review. Fragmented habitats are habitats that were once contiguous but are now separated into smaller, isolated areas. Habitat fragmentation has severe consequences for the animals that depend on that habitat for survival, including the invasion of new species and changes in landscape associated with the edge effect and even the extinction of more vulnerable populations.
Though sometimes a naturally occurring phenomenon, human activities, like construction and logging, are the leading cause of habitat fragmentation. Conservation biologists focus on ways to sustain the biodiversity of entire ecosystems, though sometimes simply reconnecting them through wildlife corridors allows a safe way to travel between them.
You should now be able to:
- Define habitat fragmentation
- Discuss how human activities and natural processes can cause habitat fragmentation
- Describe the side effects of habitat fragmentation
- Identify one possible solution to sustain the biodiversity of fragmented habitats