Why Are Dead Trees So Important to Forests?

Why are Dead Trees so Important to Forests?

Swedish forest managers do a peculiar thing when they carry out tree harvests. They cut the tops off of several trees in the area, and leave these so-called "high stumps" behind after the timber is extracted. Why do they do this? A number of studies have found that high stumps serve as habitat for a large number of species, including insects. fungi and birds, among others. As it tums out, deadwood in all forms, such as fallen logs, standing dead trees and stumps, provide essential functions today's forests.

Land managers, therefore, would be wise to incorporate deadwood into forest management, particularly after centuries of traditional practices have reduced deadwood levels to extreme lows. other agents of mortality. These killed trees then remain in forests to decay over time. However, in human-managed systems wherein trees are killed by harvesting, the wood is removed from the forest, rather than left to decompose. Without these deadwood structures, many species which depend on them are at risk. Especially in streams and water bodies, deadwood structures play important roles in creating habitat and diversity.

Dead logs can provide shelter and cover from predators for fish. Additionally, a large log can disrupt a stream's current and create pools of calm water which are ideal for some species.

On land, deadwood plays similar roles, providing cover for animals and serving as den and nesting habitat for birds and bats. Because dead logs retain such large amounts of water, they are beneficial for amphibians and other moisture-dependent organisms, especially during times drought.

Living trees benefit from the presence of their dead predecessors, as seedlings which grow on fallen logs well as a higher location to reduce shading from competing plants. As well as providing a structure that supports plants and wildlife, deadwood also serves as a substrate which organisms can inhabit. It is in a living tree's best interest to keep invading organisms out, so when a tree dies and its defenses are essentially non-existent, the Lunclaimed territory inside the tree becomes available to these organisms, including fungi and insects. Often unseen to the human eye, they inhabit the deadwood and help it to decompose. The decomposition of deadwood contributes to the productivity of forests and their soils A recently killed tree can take many decades to completely decompose, and this slow process gradually releases nutrients into the soil to be used by future generations of plants and forest species.

In addition to releasing nutrients as decomposition occurs, deadwood can support various nitrogen-fixing bacteria which can convert atmospheric nitrogen, an essential nutrient for plant growth, into a form usable by organisms. Decomposing deadwood also improves the capacity of forest soils to hold water, which helps to support various organisms and forest growth. As living plants and their roots hold soil and land in place, deadwood also serves that function, especially on steep slopes and in streams and rivers.