The percentages of sodium, potassium and phosphorus on a dry weight and ash basis at different positions in the boles and canopies of a number of trees from three experimental areas are given.

The total weights of sodium, potassium and phosphorus in the individual trees and in the tree crop are estimated.

Comparisons are made of the sodium, potassium and phosphorus contents of the various components of the ecosystems in different woodland types.

The balance of nutrients in woodlands is discussed in relation to the need for soil conservation.

We should like to express our gratitude to the Forestry Commission who allowed us to sample the trees in the experimental plots. Unfortunately, it is not possible to include all the primary data that have been collected but they can be obtained on application to the Nature Conservancy or to the authors.