Animal and plant behavior is often sensitive to photoperiods. Physical structure, pH, and mineral composition of soil limit distribution of plants and hence animals that feed on them. May be patchy, with several communities represented in one biome. Prevailing climate, particular temperature and rainfall, is most important factor in determining what kind of biome develops. A climatograph plots temperature and rainfall and shows the impact of climate on the distribution of biomes.
Lowlands receive very little rain fall, and develop thorn forests.
Nearer the equator regions have distinct wet and dry seasons and tropical deciduous forests occur. Trees releaf following heavy rains. Near the equator, where rainfall is abundant ,and the dry season lasts less than a few months is tropical rain forest. Contain more plant and animal species than any other community. Competition is strong for light, soil is poor due to the rapid recycling of nutrients.