Deforestation and the extinction crisis

By Guest blogger Murray Collins

Forests cover about a third of the world’s surface, and are home to an extraordinary array of life forms, or biodiversity. As every school child learns, the tropical rainforests are particularly resplendent in their biodiversity, containing an astonishing range of species of plants, fungi and animals. Our closest living relatives, chimpanzees, bonobos, gorillas and orang utans live in these rainforests, as did our own ancestors before walking onto the savannah: forests are our evolutionary home. Today, a billion people around the world continue to rely directly upon forests for food and fresh water; whilst the rest of us depend on them indirectly for climate regulation. However, despite their significance, huge areas of tropical forest have already been cleared, and we are destroying what is left at a very high rate.

The Indonesian island of Sumatra is a case in point. It is home to the world’s tallest (Amorphophallus sp.) and largest (Rafflesia sp.) flowers, and is the only place on earth that all of the Jungle Book animals may be found living together. So you may be forgiven therefore for imagining Sumatra to be covered with rainforest and exotic creatures. However, the reality is that most of the island’s lowland rainforest has now been destroyed to make way for agriculture, industrial tree plantations, and oil palm (Elaeis guineensis) plantations that provide oil used to make soap, crisps and cooking oil for the international market. The majority of Sumatra’s remaining natural forest is in the Bukit Barisan mountain range, but now even this is being cleared, and even within national parks.

The clearance of this forest has huge implications for people, biodiversity and climate. Sumatra’s indigenous forest people, the Orang Rimba, have lost their homes and way of life, as their forest world is destroyed around them. Migrant farmers, moving to the forest edge to clear land, find that as they remove the forest, that rivers are far more variable in their supply of water over the year, making crop production more difficult. When the forest is burned to prepare it for agriculture, the carbon rich peat which lie across Sumatra’s eastern lowlands often ignites, causing enormous carbon emissions and smog that affects both Indonesia and neighbouring Singapore ( Emissions from such deforestation and forest degradation around the world now account for approximately 15% of all carbon emissions from human activity, which contributes to climate change, and which in turn feeds back into instability in agricultural production.

When the forest is removed the diversity of the trees and plants which constitute the forest itself may be lost entirely, since some species are highly specialised and found nowhere else. Other mobile and wide ranging species like tigers find themselves increasing isolated in islands of forest in a sea of human activity. These individuals then find it harder to find mates, increasing the probability of inbreeding and producing less fit offspring in the remaining forest patches.

It is this rapid forest loss and fragmentation and its impact on tigers in particular that I am highlighting through my position as Environmental Scientist in Residence at the Royal Zoological Society of Scotland. Here I am using high resolution satellite imagery to illustrate to visitors to the new tiger exhibit ( the extent of forest loss around Berbak national park, a last home of Sumatran tigers. I will also be giving a public talk on deforestation later in the year (

Meanwhile, in the office I am developing new techniques to measure deforestation using satellite radar data with Dr Ed Mitchard at the School of GeoSciences, in the hope that better forest monitoring capacity will go some way to supporting improved forest conservation and management in the future, for instance under REDD+. (



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