Fig. 1.

Climatic characteristic of the three Mediterranean-type ecosystems studied: (a) California, (b) Spain and (c) the Cape region of South Africa. The three regions represent a gradient of summer drought severity. California has the driest and the Cape region has the mildest summers. Climatic charts of two different localities in each region illustrate this gradient. Columns represent the precipitation; solid lines the temperature; and dashed lines the water deficit in each month. Charts of the southern hemisphere localities (Cape region) have been modified to show drought between June and July for clearer comparison with Northern Hemisphere localities.