Another example of an agroforestry system with interfaces is scattered
trees in crop land. Again the unit is divided into strata, which will be areas
free from trees and areas subjected to the influence of trees. Areas under
trees can be stratified further by dividing them into concentric circles centred
on the trunk, into sectors representing different directions if there is a strong
orientation effect, or into a grid (Fig. 5). Further factors to consider in
stratification of this system are the age and size of the trees.