Trees play an important role in the life cycle of the forest for centuries even after they die. When a dead tree falls to the ground, it adds diversity to the forest floor. Soil accumulates around it and small animals find shelter underneath. A porous decaying log can store critical moisture through long dry seasons. Insects and fungi feed on it, and some fungi pump water from it to the roots of nearby trees. Eventually the fallen tree becomes a nurse log to young seedlings that feed on its nutrients. A log can take as long to decompose as it took to grow.
If the tree falls into a stream, it forms pools where young tilapia can hide from would-be-predators. The insects that feed on these logs serve as food for fish. The wood also slows the stream, minimizing erosion and trapping silt which would muddy the water. Even though logs in water decompose somewhat faster than on land, a log that fell into a stream when the park was established might still be there today. So when a tree falls in the forest and stays there, it still matters – to an Aardvark that devours the termites eating its wood, to the tilapia that swims nearby or to the African fish eagle that eats the tilapia for breakfast.
A tree that remains standing after it dies is called a snag. Eagles and hawks perch on it while hunting. Owls, bats and woodpeckers use it to nest and store food. A large snag may stand, bleaching in the sun, for as long as a century.
-Written by a conscientious Park Warden, displayed against a dead tree in the Serengeti (Tanzania)