We need to remove the old wood for the health of the trees. They are either rotten or in the process of rotting. They can increase the vitality of your trees in several ways. The first and most important is that they are moisture reserves for your trees and their associates during dry spells. Yes, the rotten log acts as a big sponge would.
Microorganisms associated with the tree extend the connection into the nurse logs.
Another way is that property owners can plant flowers, ferns and even little trees within the logs. Thus, will offer an alternative to planting them at the base of the tree. The log will also offer a winter resource for shelter for beneficial microorganisms. They are best placed somewhere in the root zone area of your tree or trees. Soil contact must be made and the nurse log left in place.