Tornado prompts Powdermill biodiversity experiment
When a tornado ripped through some areas of Westmoreland County in June 2012, John Wenzel, executive director at the Powdermill Nature Reserve, saw opportunity within destruction.
When it comes to salvage logging after windstorms, ecologists debate whether it is better for the forest to remain as is or if it is better to remove fallen timber.
“John (Wenzel) was able to see this was a big issue,” said Dr. Walter Carson of the University of Pittsburgh. “He had the foresight to say, ‘Hey, we can step in and address this issue of salvage logging in maybe the most rigorous way ever done.”
At Powdermill Nature Reserve, Wenzel, Carson and Pitt graduate student Michael Chips are teaming up with scientists, graduate students and undergraduate assistants from throughout the country to examine the impact of salvage logging on biodiversity.
Additionally, their experiment will take a look at the effect of deer browsing on the forest.
“We do want to know whether logging has a negative impact on the forest, but we also want to know the degree that that negative impact depends upon the history of browsing over the last 50 years and browsing today,” Carson said.
To conduct the experiment, about 15 acres of the “blow down” area were logged while another 15 acres were left untouched.
Approximately $15,000 gained from the timber sale, Chips said, is helping to fund the experiment. In addition, he is applying for grants.
Within the 30 acres, the team has sectioned off 64 different 20-by-20-foot plots to examine the forest’s changes in the coming years. Thirty-two plots are open to allow deer-browsing, while 32 are fenced in with what are known as deer exclosures to prevent browsing.
Deer eat the same areas of forest over and over again because of their “home range,” Carson said. The animals have strong preferences, so the plants they don’t eat become much more common, which will also be examined in the experiment.
Throughout the site, Chips has measured and tagged approximately 20,000 plants for observation.
Chips, who is using three years of the experiment as his doctoral dissertation, said since Powdermill Nature Reserve is privately owned, they didn’t have to go through any of the “red tape” studies encounter when using public land.
Studying forests takes a long time, Wenzel said, which is why the reserve’s role is important.
“We’re committed to being a research station,” he said. “Whenever these guys are doing something they have to worry about, ‘Well, how long is this going to last?’ We can commit to keeping it as their experiment for 20 years, 30 years.”
The experiment will be on pause during the winter, Chips said, as he analyzes all data collected during a vegetation survey of the forest.
He hopes to construct three large deer exclosures around the experiment area so that other scientists can come in and observe what is happening without disturbing the plots. Soil scientists recently visited the site to collect samples and measure soil compaction as a result of salvage logging.
In mere months, Wenzel said, the team has gathered measurements, mapped the blow-down areas, built a logging road and logged the sites. It has set up hundreds of boards, seed traps, pitfalls, and the deer exclosures.
“The rapid initiation of our work behind the wind event will distinguish this program from all others done in the past, and likely done in the future, as well,” Wenzel said.
While it is too early to scientifically say what trends are arising in the experiment, Chips said he has observed a lot of tulip poplar in salvaged plots and black birch in the untouched plots.
So far, the salvaged forest has produced good results for mammals and amphibians, Wenzel said.
“There is definitely a broader diversity and greater number of seedlings in the harvested areas, including wetland plants that would never have had a chance in the forest or not-harvested areas,” he said. “So, from that perspective, we can already see the differences in the initial cohort. The question, of course, is what will we have in 10 years or so? Everyone thinks they know the answer, but no one has done the work necessary to say — which is why we are doing it.”
Nicole Chynoweth is a staff writer for Trib Total Media. She can be reached at 724-850-2862 or [email protected].