Temperate woodlands are structurally simple, with widely-spaced trees and a ground layer of grasses with scattered shrubs. They are globally distributed in temperate climates with warm-season droughts. Tree foliage is typically evergreen, but may be deciduous in cold dry climates. During warm summers, productive grasses on fertile soils sustain a complex foodweb of insects, reptiles, birds and mammals. The ground flora varies with rainfall and tree cover, which creates diverse microhabitats beneath. Large herbivores and their predators are important to maintaining woodland composition, with burrowing mammals influencing soil and nutrient cycling. Fires occur periodically, but have less influence than in pyric savannas (T4.2) or forests (T2.6).