Stand Level Biodiversity Management - Module 3-B, Importance of wildlife trees

Module 3 — Stand level components
of biodiversity

British Columbia
Ministry of Forests

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Module 3, Part B — Wildlife trees — continued

Module 3

Why are wildlife trees important?

Wildlife trees at all stages provide a portion of the life support system for many species of plants, invertebrates, birds, amphibians, reptiles, and mammals. Altogether, more than 80 animal species in British Columbia depend on dead or deteriorating trees. Some of the uses include nesting, feeding, communication (drumming, marking), roosting, shelter, and over wintering.

Some wildlife tree users are considered threatened or endangered. In some places, loss of wildlife trees has already resulted in decreased abundance and variety of wildlife tree users, and may contribute to the eventual loss of some species.

http://srmwww.gov.bc.ca/atrisk/

Nine species of animals that are dependent on wildlife trees for some aspect of their life history requirements are on the provincial Red list (endangered or threatened), while 19 species are on the Blue list (sensitive or vulnerable).

Many wildlife tree users help control forest pests. Most cavity nesting birds eat insects.

For example, a recent study found that three-toed woodpeckers harvested 75 – 80% of the over winter grub population of mountain pine bark beetle in southern BC. This number of predation helps control outbreaks of forest pests.

Are there other benefits of wildlife trees?
If so, name them.

What else do you know about mycorrhizae?

Another beneficial group of wildlife tree users are the birds of prey: owls that nest in tree cavities and hawks that use the trees as hunting perches. These birds prey on mice and other rodents that often eat tree seeds or damage seedling.

Some wildlife tree users help disperse seeds, mycorrhizal spores, and nutrients. The commercially valuable conifers in BC depend on mycorrhizal (root-inhabiting) fungi that help the roots absorb nutrients from the soil.

Mycorrhizae is dispersed by small mammals (such as flying squirrels and southern redback voles) that dig up the fruiting bodies, consume them, and pass the spores through their digestive systems.

Many seeds, like spores, also are adapted to pass through the digestive systems; so seed-eating mammals and birds play a part in seed dispersal.

As well, birds and bats concentrate and transport nutrients from one part of the forest to another through their droppings.

Habitat value

Wildlife trees are an important element of natural forest ecosystems in British Columbia. However, not all trees make good wildlife trees. In general, larger size trees, either live or dead, with a sound outer shell (but with heartrot) and intact branch and bark structure, will persist longer and make good wildlife trees over time.

As well, wildlife trees are not evenly distributed throughout forest stands or across larger landscapes. Certain locations such as the areas along streams and other wet sites (riparian areas), along gullies and rocky knolls, and in stands of mixed coniferous-deciduous trees, provide more diverse habitat features.

Consequently, these areas tend to provide more opportunities for feeding, shelter, nesting, and denning when compared to wildlife trees found in other locations.

Natural disturbance factors such as fire, insect and disease attack also influence the distribution, structure, and longevity of wildlife trees.

For example, standing dead trees created by wild fire are often used extensively for feeding by insect eating birds within the first year or two following a fire. During this time, the dead trees are attacked by a variety of woodboring insects that deposit their eggs in the wood. The insect larvae and emerging adults provide food for woodpeckers, chickadees, and other birds.


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Module 3

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