Tech researchers study Appalachian bio-diversity
By Lynn Davis
Spectrum Volume 21 Issue 05 - September 24, 1998
Virginia Tech fisheries and wildlife researcher Carola Haas monitors salamander and bird populations to determine what might be the best way to harvest timber in America's forests or grow hayfields on the family farm.
She and her associates Douglas Harpole, Russell Titus, and Shannon Knapp are engaged in a number of studies that are providing a better understanding of what happens to the forest during various silvi-cultural practices, that is, the options for harvesting and re-growing forests. They are also looking at the impacts on wildlife when farmers plant exotic grass species.
Before now, little has been known about the long-term effects on wildlife from standard practices for cutting trees for the forest products used by the world's population. Moreover, relatively little is known about managing forests particularly for non-game species of wildlife or for non-timber-producing vascular plants.
The Virginia Tech researchers are studying the bio-diversity 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," Haas said, "will allow managers to assess the true costs and benefits of implementing a particular silvi-cultural practice." Sometimes, however, other disturbances besides human activities also disrupt the forest and its wildlife habitats--natural causes such as disease, insect damage, wind, snow, and ice cause disturbances similar to what results from silvi-cultural practices.
The Appalachians, the major mountain range in the Eastern United States, support the largest contiguous temperate hardwood forests in the world and are for the most part, 60 to 90 year old second-growth forests. The Appalachians are also one of the two most important centers for biological diversity in the U.S., the other being the Klamath Mountains of western Oregon.
These particular studies were conducted 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.
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."
Little is known about their surface activity patterns. Counts are taken on wet nights. Results are showing a dramatic and expected decline in salamander abundance within the first year of canopy opening. Contrary to some expectations, however, retaining a partial canopy did not help to retain salamander populations. Salamander populations seems to recover by the fourth year after a harvest.
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 said. 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."
Haas hopes the research will provide information for land managers in formulating forest practices that will best meet owner objectives and maintain biodiversity. "The underlying goals of the project are to obtain the scientific information needed to provide healthy and sustainable forests for future Americans," she said.