Figure 2.

Potential woody canopy cover percentage (τ′) in Africa estimated from the empirical relationship of Sankaran et al., ²⁰⁰⁵ and mean annual rainfall (Mitchell & Jones, 2005) at c. 10 km spatial resolution (a). Data in (a) were reduced by a random factor (0–1.0) to create a uniformly distributed pseudo-tree cover (τ) database (b). A random 5% sample (c. 15 200 data-points) from (b) was used as a calibration set for a classification and regression tree (CART) analysis which was then used to generate new CART-based estimates for the whole continent (c).