ABSTRACT
INTRODUCTION Wooded land currently covers between 30% and 35% of the world’s land surface (depending on what is counted as forest), or around 39-45 million km2
(FAO, 2003). Ecologists often distinguish between woodland and forest (479, 480). Woodland is a small area of trees with an open canopy (usually defined as the canopy giving less than 40% cover, that is 60% or more of the sky is visible) so that plenty of light reaches the ground, encouraging other vegetation beneath the trees. By contrast, a forest is usually considered to be a relatively large area of trees forming a closed, dense canopy. For simplicity’s sake, and because the underlying ecological processes at work are the same, in this chapter the term forest will be used to mean any wooded land.
