(i) The animals in forests are of various types. These could be herbivores, carnivores, microorganisms, etc. These plays an important role in maintaining the food chains.
(ii) Microorganisms convert the dead plants and animals into humus. This humus helps in returning the nutrients back to the soil. These are then absorbed by plants.
(iii) The animals also help in dispersing the seeds of certain plants.
(iv) The decaying animal dung provides nutrients.
All these activities of animals dwelling in the forest help it to grow and regenerate.