Dead Tree EcologyAs you walk around Walnut Creek Open Space areas, please notice the downed trees - mostly old oaks. Up until about ten years ago the City removed these trees. Since then these dead trees have remained in the "downed" state. There are several good reasons for this. Dead trees provide habitat for many large and small animals. The collapsed branches can provide shelter for coveys of quail, especially when the babies arrive in the spring. Acorn woodpeckers find the dead, and now softer, wood as ideal storage areas for their winter supply of acorns. In addition, there are myriads of other organisms that exist on the dying and dead tissue in the tree. If you pass a large, recently-downed tree, stop and notice the many types of shelf fungus and lichens attached to the bark. These materials provide food for several smaller animals. The shelf fungus is "feeding" on the remains of the cambium layer just beneath the bark.
It will take several tens of years for the final decay of such a tree. As it decays, there is a small temperature rise within the tree. This "heat" generated by the decay process is precisely the same amount of heat generated if you were to burn the entire tree in a fireplace. The difference is the life support systems that are active during this long decay process and that the resulting organic material will form the basis for new soils in the area - not just ashes.
Lichen on a Fallen Trunk
Small Animal Habitat
March 31, 2003