Century-long study asks how forest management affects animals, plants

WEST LAFAYETTE, Ind. — A century-long study seeks to see the forest for more than just the trees.

A group of researchers led by Purdue University has begun to sample data for a planned 100-year study designed to develop better forest management methods and measure how such practices affect resident plant and animal species.

“Our main goal is to find out how to most effectively regenerate oak and hickory forests, while examining the impact these treatments have on the whole ecosystem,” said Cortney Mycroft, project manager for the study, called the Hardwood Ecosystem Experiment.

Replacements

Oak trees have begun to be replaced by maples in Indiana and elsewhere over the past several decades.

Regeneration is important because oaks and hickories not only produce highly-valued wood products, but their edible acorns and hickories also support larger wildlife populations, Mycroft said.

Ultimately the researchers plan to develop a decision support tool that will help people like forests managers and landowners predict the likely effects of specific management decisions.

“We want to give people the ability to understand — at the outset — what the different implications are for a particular forest management strategy,” said Purdue principal investigator Rob Swihart.

Studies

The experiment will examine the effect of different management methods on endangered species like timber rattlesnakes, Cerulean warblers and Indiana bats, said Purdue Extension wildlife expert Brian MacGowan.

Researchers also will study songbirds like the worm-eating warbler, small mammals like voles, woodland salamanders, box turtles, moths and beetles.

“This is really the first study of its kind,” MacGowan said. “None to date has been this far-reaching or widely oriented, looking at harvesting effects on a comprehensive range of animals.”

Local input

Another important goal of the study is to involve visitors and nearby landowners in the process by getting their input.

“We want to get a feel for current opinions of visitors and nearby landowners — as two distinct groups — about the study’s management practices,” Mycroft said.

“We will then look to see how we can accommodate their input and keep them informed about the research.”

Aging

As forests age, they progress through developmental stages marked by changes in the makeup of trees and other plants.

Forests in Indiana and elsewhere continue to grow older and are moving past the point where oaks can regenerate, said Mycroft, a forest technician at Purdue. That is because shade-tolerant maples can sprout and grow to intermediate sizes in the oak forest understory.

These medium-sized maples are well-suited to fill gaps that open up in the canopy, allowing them to slowly spread and eventually dominate previous oak territory, she said. Oaks require sunlight to sprout and grow, Swihart said.

Size, type

Researchers will use various harvesting methods, or treatments, for opening up clearings of various sizes.

This will help them better understand the relationship between the type and size of the harvesting technique and the subsequent response of oaks and other trees, non-woody herbaceous plants, and animals, he said.

Effects

Currently, not enough data exists to predict the effects of such clearings.

Some creatures like woodland salamanders, which require shade and moisture to survive, seem unlikely to benefit. Others, like certain bird species and rattlesnakes, seem likely to gain. But scant data exists to answer such questions, and this experiment aims to fill in the blanks, MacGowan said.

“As stewards of Indiana’s second-largest forested land base, the Division of Forestry thought the time was right to put in place a truly unique research project,” said John Seifert, head of forestry for the state’s Department of Natural Resources, a primary collaborator and funder of the project.

“The scientific knowledge that will be gained from this research will have long-term impacts on both public and private forest management in the state.”

Cutting

Treatments examined include even-age selection — in which all trees of a certain age class are cut — and single-tree treatments, in which desirable trees are allowed to grow while others are harvested.

One type of even-age treatment to be studied is clear-cutting, wherein every tree over a certain size is cut. Selected at random, one site to be clear-cut is adjacent to a state forest road.

“However, the opening will become flush with vegetation rather quickly. I think people will be amazed,” Mycroft said. “This will be an optimal site to see how quickly forests can regenerate.”

Moreover, on clear-cut sites — as with all harvest sites — old logs and other so-called “down woody debris” will be left as an important habitat for salamanders and small mammals, Mycroft said.

Researchers will use results from their study to inform management practices as they go along, Swihart said.

“We call this adaptive management,” he said. “We really want to learn from our research. If we find, for example, that a certain management strategy has a dramatic adverse effect, we will certainly call into question the efficacy of that method and possibly not use it in the future.”

The researchers will conduct their work in nine 200-acre research areas within the Morgan-Monroe and Yellowwood State forests in Indiana. Research areas were randomly assigned one of several management practices, Mycroft said.

These practices will be applied in harvests to occur every 20 years, the first commencing this summer. Data collection on forest composition and animal abundance began two years ago and will continue for the remaining 98 years.