August 2008 Asheville Field Office press releases, story ideas, and media advisories
August 4, 2008
Botanists Blitz Area Cliffs for Endangered Plant
Even for a botanist, it was an unusual workday.
Chris Ulrey, a botanist with the National Park Service, tossed the rope over the cliff’s edge, announced his descent, and began dropping down the cliff face. But any semblance to recreational rappelling vanished when, dangling from the rope, Ulrey lifted the hammer drill that was slung over his shoulder, put a hole in the rock next to a cluster of endangered plants, nailed a numbered tag into the hole, and began yelling out plant measurements to a note taker below.
The rappelling, tagging, and data collection is part of an extended effort to track the endangered spreading avens, a plant found only on a handful of cliffs and rocky outcrops on some of the highest mountains in the Southern Appalachians.
“The goal is to get an accurate picture of the abundance and well-being of as many spreading avens populations as possible,” said Carolyn Wells, a botanist with the U.S. Fish & Wildlife Service.
Wells and Ulrey are part of a team canvassing the small number of mountaintops where spreading avens is found. The team also includes botanists from the USDA Forest Service, North Carolina State Parks, North Carolina Natural Heritage Program, Grandfather Mountain, Tennessee Department of the Environment and Conservation, and the Archbold Biological Research Station.
Spreading avens grows in rosettes, with a circular pattern of small leaves just above the ground and a tall center stem bearing bright yellow flowers. The plants grow in patches ranging in size from a single rosette covering less than a square inch to hundreds of rosettes covering two square yards. The scientists will measure the size of each patch, tagging each with a metal tag, then use a laser range finder to map the patches in relation to one another. Additionally, they’ll search for individual seedlings, tagging them with a metal pin. Returning annually to verify the presence of the tagged plants and patches, remeasure the patches, and note new seedlings will allow the botanists to track changes in the population.
Once five to six years of data have been collected, scientists can run population viability analyses to estimate the extinction risk for each population.
“A population viability analysis looks at two things – how quickly new plants are being added, and how quickly plants are dying, basically birth and death rates,” explained Wells. “It then estimates the risk of extinction at various points into the future, based on these rates. If we see a population declining, we can try to determine why and address the problem.”
Spreading avens was listed by the federal government as endangered in 1990, with one of the biggest threats being inadvertent trampling and associated erosion from hikers and climbers. It has also suffered from over-collection and botanists suspect the encroachment of competing shrubs also poses a threat.
A possible growing threat to the plant that isn’t directly addressed by this work is global warming. Spreading avens is adapted to some the coldest places, with the harshest weather, in the Southern Appalachians, and biologists expect two possible outcomes from warming temperatures. In one scenario, warmer temperatures simply enable lower-elevation plants to move up the mountain, replacing cold-weather plants. Another scenario holds that encroaching plants are held at bay by harsh weather events, such as snow and ice, which periodically scour the rock surface, clearing away less hardy vegetation and opening up habitat for spreading avens. Less frequent snow and ice could mean the rock outcrops wouldn’t be scoured, allowing competing vegetation to grow and out-compete the endangered plant. While the work done by the botanists won’t provide a clear, cause and effect link between global warming and any impacts to the plant, it will show population trends over time that may be correlated with changes in temperature.
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