Trees and soil recovery

Introduction As long ago as 18411 it was known that trees can cause movements of adjacent ground if the soil contains appreciable quantities of clay. However, it is in comparatively recent times that researchers in the UK have attempted to understand how the process of tree‐induced ground volume change comes about. In the first instance, studies were inspired at the Building Research Station, immediately following the Second World War, by investigations of claims for compensation for bomb damage that revealed the close proximity of trees to buildings that were remote from locations where bombs had fallen. These studies concentrated on establishing the ability of vegetation to dry the ground, and on determining the depth at which building foundations should be placed to prevent damaging movements occurring through the action of light vegetation. This early work also pointed out the risks of subsidence from tree root activity and the need for deeper, piled foundations when building close to trees. Though several BRS publications were issued, the problem was not widely appreciated.