Humus form is the features of the topsoil and plant litter in a biome, such as mull humus form in deciduous forest or mor humus form in coniferous forest. Dead organic matter, such as leaves, decomposes into humus. Sometimes soil animals mix underlying mineral soil with the humus. This is also part of the humus form.
Humus form is important in ecosystem management, such as forest management, as it influences a forest's ability to regenerate through the establishment of new saplings and seedlings. Humus form is affected by land use, vegetation dynamics, pollution, and climate change.