Dead, standing trees in a forest are sometimes called ‘snags’. These woodland features support a complex system of life. When a person learns the importance of snags to wildlife, they are likely to appreciate dead trees more than they previously had. Some may come to appreciate them more than live trees!
A Wildlife Biologist once told me there are more living cells in a dead tree than a live one when one considers the plant and animal life utilizing a tree after it dies. His statement may or may not be accurate, but one thing is certain. Dead trees clearly provide support for a lot of living things from decomposers to birds and mammals.
Leaving one snag per acre was once the recommendation of many forest biologists. However, newer research indicates that additional snags of varying heights and diameters provide further benefits to wildlife.
In Idaho, about 50 species of birds and 25 species of mammals nest, roost, forage or take shelter in snags. Plants and invertebrates also benefit from snags, which eventually fall and provide watershed protection and nutrients which create rich forest soils.
Before dropping a snag for firewood, look for any fungal growths on the main trunk. Don’t worry about a few, but if there are numerous fungi on the tree, there are better trees around to heat your home. A snag showing a number of fungi on the bark has already begun to decay. Once fungi begin to appear on a tree, the firewood you collect from it will not produce as much heat for your home as firewood from a more solid tree. If you put in the work to cut a tree to the ground, reduce it to firewood length, split it, haul it home, unload it, stack it, and ultimately put it in your stove…you want to get lots of heat from it to make it worth the work you did!
When cutting firewood, you may want to look first for trees that have uprooted and are suspended horizontally off the ground by other fallen trees. These will be dryer than trees lying flat on the ground that are soaking up ground moisture. A tree that fell over a year ago that has had air circulating on all surfaces of the tree may be seasoned enough for immediate use. Trees on the ground are fine if you can cut, split and season them for a year before burning.
On private property, firewood gatherers can cut live trees which are crowded and subordinate to those around them. These will need a full year or more after cutting and splitting to season before burning. Cutting these trees can actually improve forest health by reducing competition and giving stronger trees room to grow.
Cutting live trees on public lands is not permitted by most land management agencies. Live trees are public assets that have market value. In most cases, live trees on public land can only be cut by professionals who are trained to select the right trees to cut and those to leave for habitat and eventual harvest in the future.
Dead trees can be cut on many public lands but only in specified areas, and firewood cutting permits are required on most public lands.
When selecting firewood trees, look for any signs of active wildlife use such as nesting cavities or signs of roosting. Woodpecker holes indicate there are many insects already inhabiting the tree, and insects are the last thing you want to bring into your home. Leaving such trees standing will benefit wildlife.
Large diameter snags remain standing longer than smaller ones, so they are good choices to leave for wildlife. Snags measuring 15 inches in diameter or larger at breast height are valuable to wildlife and will remain standing longer than most of us will be around if we leave them.
Leaving snags of a variety of diameters will benefit more species. Woodpeckers typically use trees at least 15 inches in diameter, raccoons generally use trees in the 24 inch diameter range and black bears will use snags 40 inches in diameter and larger.
When cutting wood on the national forest, you might even notice trees bearing a sign saying “Wildlife Tree”. This sign indicates the Forest Service has observed wildlife use of this particular dead tree. Such trees must always remain undisturbed as there are likely several species of birds or mammals utilizing this particular snag.
The species of tree snag is also important. In northern Idaho, Ponderosa pine, western larch, hemlock, and Douglas fir make long lasting snags. Cottonwood and aspen snags may not last as long, but they are valuable because they grow in riparian areas that are already conducive to wildlife habitation.
A wood stove is a great way to heat your house. By selecting which trees we cut, we can provide comfortable homes for ourselves…and for wildlife.