We all know forests are hugely important places. But why exactly should we care about them? And what, in fact, are they? Oddly, the second question is rather harder to answer than the first. Forests are home to a large proportion of the world’s biodiversity. They play a major role in regulating climate, both globally and locally; they contain huge quantities of carbon, stored in the wood and below ground, which might otherwise enter the atmosphere as greenhouse gas. They stabilize soils and help prevent erosion, and have a major influence on the water cycle, affecting the supply and flow of freshwater. They provide a wealth of material resources: timber, of course, but also other products including wild foods, rattan from palms, medicines, fuelwood and charcoal. And they create some of the most beautiful and inspiring landscapes on Earth.
But what is a forest? It’s a place with trees, of course. But it’s never as simple as that. How many trees exactly? And what exactly is a tree? Do plantations count? Parkland? Bamboo groves? It’s hard to get agreement on this so it’s not surprising that people may have very different ideas on what constitutes a forest. This in turn means that there are many different estimates of how much forest there is, both globally and in particular places, and how fast the area of forest is changing. The Food and Agriculture Organization of the UN (FAO) considers forests to be anywhere with more than 10 per cent tree cover, but that’s not very much at all. On this basis, there are just over
40 million km2 of forest in the world – or about 30 per cent of the Earth’s land area, and it’s probably about half the area that would be forested without the impact of people. Only about 14 million km2 of forest remains largely unaffected by humans, and existing forests are very unevenly distributed. Over half of the total forest area is found in just five countries, and more than 60 countries have less than one tenth of their area forested, with 10 of these having no forest at all.