Salamanders May Reveal Best Way To Manage Forests, Virginia Tech Researchers Report

Studies by faculty member Carola Haas, research associate Douglas Harpole, and graduate student Shannon Knapp are providing a better understanding of what happens to the forest during various harvesting and regeneration practices. They presented their research at the 83rd annual Ecological Society of America meeting at the Baltimore Convention Center Aug. 2-6.

The Monday, Aug. 3, presentation by Harpole, as part of the Animal Population Ecology 1 symposium, focused on the nighttime findings of the effects of the seven different silvicultural treatments on terrestrial salamander species richness and relative abundance. Why study the salamander? The greatest density and diversity of salamanders in North America occur in the southern Appalachians. They are an important link in the food chain between tiny insects in the leaf litter and larger vertebrates such as birds and mammals. Salamander habitat is especially sensitive to forest management practices that open the canopy.

The Virginia Tech researchers are studying the biodiversity in southern Appalachian forests to examine the effects of seven major regeneration alternatives (from the least to the most canopy disturbance): unmanipulated control, or no disturbance (for baseline comparison), understory herbicide application, group selection (removal of patches of trees every few years to create small stands of different ages and sizes), two shelterwoods (harvesting all but 20-60 percent of the tree canopy), two-age regeneration method (saving some valuable trees for later harvest), and clearcut regeneration.

"We hope the comparison of alternate management practices will allow managers to assess the true costs and benefits of a particular silvicultural practice," Haas says. The results could also help manage forest recovery from disease, insect, wind, snow, and ice damage.

The Appalachians, the major mountain range in the Eastern United States, support the largest contiguous temperate hardwood forests in the world and are largely 60- to 90-year-old second-growth forests. The Appalachians are also one of the two most important centers for biological diversity in the United States, the other being the Klamath Mountains of western Oregon.

The research reported was conducted on wet nights in the mountains of southwest Virginia and West Virginia, where salamander populations may vary greatly from one side of a mountain to the other. Before harvest, species richness varied among sites, with species ranging from eight to 12. Relative abundance differed significantly among three of the seven sites.

Results in the five-year study show a dramatic and expected decline in salamander abundance within the first year of canopy opening, Haas says. However, retaining a partial canopy did not help to retain salamander populations. Salamander populations seems to recover by the fourth year after a harvest.

After harvest, salamander abundance declined significantly on five of the seven treatments. "This tells us that in these habitats salamanders are extremely sensitive to any form of canopy disturbance," Harpole said. "Managing certain areas of forest intensively and then allowing longer periods of time between disturbances may be more suited to maintaining populations of salamanders than regeneration methods such as group selections, which require repeated entry into the stands."

In a poster presentation, Knapp and Haas show the impacts of timber harvesting on surface activity in terrestrial salamanders. These creatures spend most of their time in cool, moist underground environments, but they must surface to forage and breed.

These animals have complex behaviors, communicating by chemical signals and defending territories. "We're trying to determine whether changes in habitat that result from canopy disturbance have an effect on the salamanders' surface activity patterns," Haas elaborated. Estimates of salamander population size are based on counts at the surface. "When we observe changes in numbers, we need to know whether that is just a result of changes in behavior or if there is really a change in population size.

Editor's Note: You can learn more about Dr. Haas' work at http://www.fw.vt.edu/fisheries/HAAS.