Dead Trees Host Living Creatures

By Phil Cooper, Idaho Department of Fish and Game For 30 years, I have lived in homes heated by wood stoves. I have come to really enjoy the winter warmth that comes from sitting near a wood stove on a snowy day. This is the time of year I gather wood for heating our home. Next winter's supply is cut, split and stacked. I am working on wood for the following winter, staying a year ahead so the wood has plenty of time to season. Dry, checked wood is the best fuel you can get to warm a house. Well-seasoned wood also burns cleanly with a minimum of smoke added to our air. With the soaring costs of propane, natural gas, and electricity, a lot of other people are out and about collecting wood for heating. Saving money is, after all, the biggest reason most people heat with wood. Firewood gatherers typically look for dead standing trees they see in the forest. These woodland features, called snags, support a complex system of life. By understanding a little about snags, people have come to value them and leave a few here and there to benefit 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 that create rich forest soils. Some snags I have cut down in the past were left on the ground because I discovered too late they were too far decayed to make good firewood. Unfortunately, I had dropped them before or while they provided a home for wildlife. Before dropping a snag, look for any fungal growth on the main trunk. If you see any, there are better, more solid trees around to heat your home. A snag showing fungus on the bark has already begun to decay and will soon be a home for wildlife. When selecting firewood trees, look for any signs of current 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 stand if we leave them. While large diameter snags can provide homes for more species of wildlife, leaving snags of a variety of diameters will benefit even more species. Woodpeckers typically use trees at least 15 inches in diameter, raccoons use trees in the 24 inch diameter range and black bears will use snags 40 inches in diameter and larger. Wood cutters on the national forest 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 should always remain undisturbed as there are likely several species of birds or mammals using this particular snag. A snag's species is also important. In our area, ponderosa pine, western larch and Douglas fir make for good and durable snags, as do cottonwood and aspen because they normally grow in riparian areas already conducive to wildlife habitation. Leaving one snag per acre was once the recommendation of many forest biologists. However, it appears that additional snags of varying heights and diameters may provide further benefits to wildlife. When cutting wood, I now look first for trees that have uprooted and are horizontal to the ground. I occasionally cut live trees that are crowded and subordinate to those around them, because I have a full year and a half to let them season. There are always enough uprooted trees and crowded live trees to gather all the firewood I could ever need. Idaho Fish and Game has produced a nongame leaflet called "Dead Trees and Living Creatures: The Snag Ecology of Idaho." The leaflet describes many of the benefits of snags to wildlife and describes the ways many different species of wildlife that use snags. The publication is available free at any Fish and Game office. Phil Cooper is the regional conservation educator in the Panhandle Region.