Biomes are climatically and geographically defined as similar climatic conditions on the Earth such as communities of plants, animals and soil organisms. Biomes are defined by factors, such as plant structures (such as trees, shrubs and grasses), leaf types (such as broadleaf and needleleaf), plant spacing (forest, woodland and savanna) and climate. Unlike ecozones, biomes are not defined by genetic, taxonomic or historical similarities.