Lets talk about how the loss of habitat is probably the greatest threat to life on Earth . Every living thing needs a home, somewhere to live, without which it will die. To protect biodiversity, we must protect habitats. But our forests, wetlands, grasslands, rivers and coral reefs are disappearing at an alarming rate as we find ourselves places to live and produce everything that we want and need .
We extract natural resources for our own use to make way for our activities such as urban development, agriculture, industries and building roads. The massive growth in the human population throughout the 20th century has had the greatest impact on biodiversity, more than any other single factor. All forms of human development change the natural world. Examples include commercial forestry which involves both road-cutting and harvesting of trees. Dams change river flow patterns, oxygen levels and water temperatures and prevent fish from swimming upstream to breed. Farmers clear land, extract water to irrigate crops and use pesticides and fertilizers that pollute both land and water. Urban development destroys natural habitats, clearing and paving land, and also comes with increased industrial activity, pollution and transport. Fishing also causes habitat changes particularly destructive techniques like bottom trawling which essentially plough the ocean floor, destroying the habitat. As of 2015, over 22,000 species are currently classified as threatened and the reason for that is habitat loss for 85% of them.
So far, about half of the world’s original forests have been lost, with tropical forests being one of the most threatened habitats on Earth.
Habitat loss, particularly in forests, is closely linked with human population density and also agriculture. If we look all around the world and since records began, then Europe and Asia have lost some of the largest areas of forest to date. Forests are being lost due to over harvesting and overgrazing by livestock and they’re being cleared at a rate that is faster than they can regrow or we can replant. Cultivated land now covers a quarter of the Earth. On a more positive note, threats to temperate forests are actually decreasing thanks to preservation and reforestation efforts. Coastal habitats such as estuaries, sea grasses, mangroves and coral reefs are particularly threatened .
one of the main reasons for that is about 40% of the world’s population lives within 60km of the coast. Such massive global development along our coastlines results in the destruction of these vulnerable coastal habitats by cutting down mangroves and beach forests, by filling in and draining wetlands and the increased pollution and sedimentation that comes from urban runoff and industry. There are many other vulnerable habitats around the world which we can’t cover here but scientists have been working to predict how many species might be lost if we continue to destroy habitats at the current rate. At the moment, the estimate is between 2-3% of all species on Earth – that’s about 10- 15,000 species per year.
Some species have particularly specialism habitat requirements – they might live on the top of a mountain, a specific island or within a particular lake. These species are particularly vulnerable to changes or loss of their habitat. They simply can’t adapt to those changes and they have nowhere else to go. Even if a habitat is not completely destroyed, it can often be broken up or fragmented by human activities. Things like roads or dams reduce the size of a habitat which might make it an viable for a population – there’s simply not enough room left for a species to live, they can’t find a mate or there’s not enough food. Breaking up or fragmenting habitats also creates a situation known as ‘edge effects’. If you think about it, these habitats form little islands and around those edges, you get different conditions of wind, weather or even noise coming from things like roads. In this case, it might be those conditions are much less suitable for the species that live there, meaning that the habitat is even more compromised. Although the overall situation surrounding habitat loss is obviously very concerning, the good news is that we have a lot of available solutions. It’s now a question of scaling up and replicating those. We have certified sustainable fisheries that reduce their impact on the habitats in the ocean. We have organic agriculture that protects natural woodlands and hedgerows. We have legislation and associated enforcement that stops the most destructive practices such as dynamite fishing or deep-sea bottom trawling. There’s an increasing number of protected areas that look after the most vulnerable species and their habitats. We’re establishing corridors that connect species enabling them to move between vulnerable habitats, to find their mates and enable them to have a viable population and to have sufficient food to survive and thrive. Test what you’ve learned in the quick learning check then the next video will tell you how over exploitation is threatening biodiversity.