Deciduous forest
A moderate climate and dominance of hardwood deciduous trees occur across much of eastern North America, Europe, and Asia. Much of this biome has been subjected to human disturbance for agriculture and urban development. There are usually 15 to 25 tree species, including maples, oaks, poplars, and birches. Springtime sun passes through seasonally leafless trees to reach a diverse understory flora. Soils are rich in nutrients from annual leaf fall, and the moderate temperatures and precipitation promote decomposition, while the cool winters promote accumulation of organic materials. Soils contain a diversity of microbes and fungi, along with the protists and invertebrate animals that feed on them. Insects, birds, and mammals are relatively diverse, joined by snakes, lizards, and amphibians.