Whilst looking at the importance of snags and dead wood in Sanjay Gandhi National Park(SGNP) in Mumbai I wanted to know how important these were in our forests.
A good forest is where there are plenty of dead trees, scattered on the forest floor waiting to rot in a natural way. Dead wood is a natural and essential component of the forest ecosystem. A multitude of species specialized in feeding on dead wood, and the number of species eating these "dead wood eaters" is even greater. Those groups of coexisting organisms are dependant on a supply of dead wood.
Bacteria and fungi and live on the dead wood. Many species of insects feed on such bacteria and fungi. Those insects serve as a food for other insects, arachnids, amphibians, reptiles, birds and mammals. In addition fungi which decompose dead wood are a host for other species of fungi which parasitize on them. The organic matter that was once a tree, passes through a chain of organisms and returns to the environment, where bacteria and fungi decompose it to simple chemical substances, that are again used to "build" new generations of trees.
The first bird species that I can think of is the woodpecker and several of them have a penchant for feeding on snags – I have seen the beautiful Heart-spotted Woodpecker looking for grubs, beetles, etc., on them. Hollow tree trunks can be homes for woodpeckers, bees, other insects, as well as rodents and small mammals.
I read that dead wood: (i) is a source of nitric compounds needed for growth of plants slowly released into the soil (ii) keeps carbon atoms which delays the release of carbon dioxide (iii) enriches the forest floor.
Snags are standing dead trees often with their top branches missing.
Meanwhile, look out for mushrooms and some bright and colourful fungi on trees and fallen tree trunks.