Why are
wildlife trees important?
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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.
www.env.gov.bc.ca/serisk.htm
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.
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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. |
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 Are
there other benefits of wildlife trees?
If so, name them.
 What else do you know about mycorrhizae?
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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 |
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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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