574 Land-Use Patterns, Historic Figure Oxlip (Primula elatior) flowering in abundance among hazel (Corylus) shoots of year’s growth since coppicing Hayley Wood, Cambridgeshire, England Figure Eucalyptus forest years after being logged for the third or fourth time Note the abundant regrowth and ground vegetation Merimbula State Forest, New South Wales temporary clearings and of grassland away from woodland On pollen evidence, something like these permanent open areas already existed in wildwood Wood-Pasture and Savanna Where the environment becomes too dry or cold for forest or where there is too much grazing, forest changes into nonforest in various ways The trees may suddenly stop, or there may be a zone of trees reduced to the stature of shrubs, or a mosaic of patches of forest and patches of nonforest Alternatively, there may be a zone, often of great extent, of scattered trees among grassland This constitutes tropical and subtropical savanna ecosystems and their extensions into northern latitudes The trees may be single, as in the wood-pasture ecosystems of England, the dehesa landscapes of southwestern Spain, and the eucalyptus savannas of Australia Or they may be in groups, as with the oak and elm motts of middle Texas (Figure 9) This depends on the properties of the trees: Texan Quercus fusiformis and Ulmus crassifolia are clonal trees that sucker It used to be thought that the ‘‘natural’’ savannas of Africa and Australia were very distinct from the semiartificial treed grasslands and treed heaths of Europe, which were regarded as