The structure and composition of vegetation and the functioning of terrestrial ecosystems, which at a local scale are shaped by environmental factors such as temperature and moisture, are also influenced by global climate patterns. This is seen in the biogeography of vegetation and in the global carbon cycle, especially net primary production. The geographic distribution of biomes is closely correlated with measures of temperature, precipitation, and evapotranspiration. So, too, are annual net primary production and decomposition rates. Long-term changes in climate alter the biogeography and functioning of Earth's vegetation. Global models of terrestrial ecosystems provide a quantitative framework to understand planetary ecology and the role of terrestrial ecosystems in the climate system.
The broad influence of climate on macroscale ecology is evident when the complexity and diversity of terrestrial communities and ecosystems are reduced to a few biomes, or broad classes of vegetation (e.g., forest, grassland, shrubland, or desert). The natural vegetation of Earth has a distinct geographic pattern that corresponds to climate zones (Fig. 2.5). The close correspondence between climate zones and biomes is readily apparent as climate zones such as tropical savanna, tropical rainforest, and tundra are named after vegetation (Table 6.1).
Tropical evergreen forests (tropical rainforests) are the dominant vegetation in hot, wet equatorial regions of South America, Africa, Southeast Asia, and Indonesia. In these regions, monthly temperatures are warm year-round, precipitation is abundant, and there is little seasonal variation in temperature or rainfall. Plants grow rapidly and continuously.