|
The major problem in mapping forests is to decide at what point tree cover becomes dense enough to be called a forest rather than, say, an open
woodland. There is no straightforward answer. The UN Food and Agriculture Organization (FAO) classifies as forest any area with more than 10 per cent
canopy cover. But this very wide definition includes many areas which few would regard as forests. A more satisfactory definition is one covering closed
canopy forest: any area with over 40 per cent crown cover. This works well with broadleaf or mixed coniferous or broadleaf forests, but less well with
purely coniferous forests, where canopy cover is often less than 40 per cent.
|