Studying dead trees is an excellent way to learn about the role of plants and animals in a community. Although many communities are big and complex, the small communities that form around fallen trees are fairly simple to observe and study. Decomposing logs provide nutrients and shelter for many plants and animals. Within a single log it is possible to find producers, consumers, and decomposers, that together form a food web.
When a healthy, standing tree dies, it is called a snag. When the snag falls to the ground, it becomes a log and begins to decompose. Some species, such as insects and fungi, help with the process of decomposition. Weather conditions, such as wind, rain, and light, also play a role in decomposition.
Logs decompose at different speeds because trees vary in characteristics such as the hardness of the wood and thickness of the bark, and are affected by different types of decomposers. When the log has completely decomposed, it becomes soil.
Scientists classify a decomposing log according to different classes of decay.