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