If loggers left waste wood behind after harvesting a forest, it would help small forest mammals and their predators, according to a study published in the Journal of Mammalogy.
In North America and Europe, clear cutting is the most common way to harvest lumber, and waste wood is often burned in order to avoid leaving fuel for wildfires, or hauled away to use in bioenergy production.
Canadian researchers measured both the abundance and diversity of small forest animals in different situations. Surprisingly, the number and diversity of species was no less in clear-cut forests where all debris was removed, than in in mature undisturbed forests.
What was different in the two situations was that generalist species dominated in the debris-free areas, and there were more specialist species in uncut forests. Generalists like deer mice and chipmunks are adaptable and can live in various habitats, but specialists need certain conditions.
The specialist species, such as the southern red-backed vole, are valuable as prey, as consumers of plants and insects, and as distributors of spores.
The red-backed vole is important food for martens (a species of concern), and for other animals. Once a forest is clear-cut, red-backed voles leave and do not return for decades, according to the authors. Handling logging debris in a way that provides habitat could change that, according to their observations.
The authors of “If we build habitat, will they come? Woody debris structures and conservation of forest mammals,” caught and tagged animals at three places in British Columbia from 2007 to 2009. They followed humane practices for trapping, handling, and releasing the animals, they said.
The best thing loggers could do for animals is to leave big piles of coarse woody debris (CWD), according to the authors. Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M. F. Lindgren, and Douglas B. Ransome, Faculty of Forestry, University of British Columbia, wrote, “Maintaining mammal diversity, as a component of biodiversity, is a major conservation goal in commercial forest landscapes.”
They found that specialist species were very abundant in naturally created big piles of CWD. Mysteriously, diversity was lower where tornadoes had created the piles but higher in piles near rivers. The authors called for more experiments with different sizes and placements of wood piles.
It seemed valuable to leave debris at least six feet high and twenty feet long, and it helped the animals if the piles were long enough to provide cover from the clear cut area to the nearest wooded area, according to the authors.
Loggers could and should provide places for woodland animals by leaving scrap lumber in the field, according to the researchers.
Many mammals use CWD, including “carnivores such as coyotes (Canis latrans), red foxes (Vulpes vulpes), lynx (Lynx canadensis), cougars (Puma concolor), weasels (Mustela spp.), and American martens (Martes americana) also use CWD, particularly logs, as habitat for denning, nesting, and foraging,” wrote the authors.
When forests are cut, creating scrap piles can help small and large creatures to live.