During the time it takes a tree to die and decompose, thousands of insects may use that tree for food or shelter. In fact, there are so many insect species adapted to this lifestyle that dead trees are often called the apartment houses of the insect world. This description is quite appropriate because the insects in a dead log or stump live right next door to one another, feeding, building shelters, and reproducing in the same habitat at the same time.
Even before a tree dies, there are insects that tunnel into the cambium to feed and reproduce. These insects often weaken the tree and may infect it with spores of wood-destroying fungi. Once the tree is dead, other insects move in to feed on the wood or to excavate galleries where they lay their eggs. As the wood decomposes, the habitat changes. Insects feeding in the cambium eventually cause the bark to loosen and fall off. These insects move away, but other species come along after them. Rain water penetrates the wood fibers and accelerates decay. Small, soft-bodied insects that feed on fungi are able to survive in these moist conditions. Decomposers gradually replace larger herbivores, and finally, soil insects take over and convert the stump or log into a type of organic matter known as peat.
The change in species composition that takes place as a dead tree stump decays illustrates a similar kind of change that takes place in larger communities. This process is known as succession. It occurs in nearly all living communities, from forests to ponds and from sandy beaches to volcanic islands. Each living organism affects its surrounding in one way or another, making life sometimes more, sometime less difficult for itself or for other members of the community. In a forest, the process of succession may last for hundreds of years. Eventually, a stable (climax) population develops, but even then, small-scale dramas of succession are replayed every time another tree dies.