Fire, ice, and insects, as well as human economic demands, can damage forests, and the long-term environmental, business, and social consequences could be dire. College of Forestry and Wildlife Resources researchers are studying the intricacies of animal and plant recovery to learn how to manage forest use and repair damage – whatever the cause.
Fisheries and wildlife sciences assistant professor Carola Haas and forestry professor David Smith teamed up several years ago to “listen to the forests.”
They study the richness of the southern Appalachian hardwood forests, particularly the impacts of silviculture upon forest biodiversity. Forestry professor Bill Stuart explains silviculture as “management of forest stands — the timber, wildlife, water, whatever is in the forest.”
What do the forest scientists seem to be seeing and hearing? If the salamander, flower, and songbird populations are healthy, then you can sleep easier at night knowing that your forest is in a sound state.
Haas and Smith are engaged in a number of studies that provide a better understanding of what happens to the forest during various silvicultural practices, or regeneration alternatives. Before now, little has been known about the long-term effects of standard practices. Moreover, relatively little is known about managing forests, particularly for non-game wildlife or for non-timber producing vascular plants.
The researchers have studied biodiversity in southern Appalachian forests to examine the effects of seven regeneration alternatives, from the least to the most canopy disturbance: unmanipulated control for baseline comparison, understory herbicide application, removal of patches of trees every few years to create small stands of different ages and sizes (group selection), harvesting all but 20-60 percent of the tree canopy (two shelterwoods), two-age regeneration, and clearcut regeneration.
“We hope that the comparison of alternate management practices will allow managers to assess the true costs and benefits of implementing a particular silvicultural practice,” Haas says.
The Appalachians, the predominant mountain range in the Eastern United States, have the largest contiguous temperate hardwood forests in the world. They 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 United States, the other being the Klamath Mountains of western Oregon.
The study
The long-term, replicated study focuses on diversity and population health by measuring floral and terrestrial salamander diversity and salamander and songbird reproduction. Why the salamander and songbird? The greatest density and diversity of salamanders in North America occur in the southern Appalachians and almost half of the 58 species of migrant forest birds breed in these mountains.
Additionally, salamanders 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.
“We collected baseline data on abundance and diversity of plants and salamanders on six sites in the Jefferson National Forest of southwest Virginia and on two sites in West Virginia,” Haas explained. “We have questions to answer.”
How would floral diversity differ among the seven alternatives? Would the regeneration alternatives result in loss or gain of rare or sensitive floral species? Would salamander species be affected? Would songbird reproductive success change near forest canopy openings that have been created by forest products harvesting operations?
The research team set up the study so that in 60 to 90 years future researchers could assess if the forests will be similar to what they are today.
Early results
To date, the research scientists have found 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.
For the first three years, salamander populations continued to decline on all plots with canopy removal, while remaining stable on plots with an undisturbed canopy. “Early samples of the field work we are doing now suggest that salamander populations may be recovering by the fourth year (after tree harvest),” Haas says. “If this trend continues, the question becomes whether different regeneration methods foster faster recovery.
“As for the songbirds, they lose many nests to predators, such as raccoons, where forests are removed for residential development and agricultural uses,” Haas elaborated, “but small, temporary forest canopy openings — such as with the group selection method of harvesting — do not seem to cause an extreme decline in nesting success.
“Regarding floral species, preliminary results from one study site show no relationship between intensity of canopy disturbance and loss of herbaceous plant species one year after trees are harvested,” the wildlife researcher reports. “Several species that require disturbance to flower and spread increased in the more intensely disturbed sites.
“While these results are preliminary,” she says, “the data are suggesting that the different levels of canopy disturbance may have substantial effects on multiple components of forest systems.”
The way Americans view their forests, both private and public, has been changing in recent years. Pressure has been mounting to enhance the compatibility of forest products harvesting with a broader array of values and uses, including outdoor recreation, wildlife habitat, watershed integrity, water quality, and visual amenities.
David Smith sums up, “We hope our work 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.”