HOUGHTON - By studying clustering moose carcasses on the landscape, scientists at Michigan Technological University actually can link wolves with nutrients in soil.

Joseph Bump, assistant professor of wildlife ecology at Michigan Tech has been part of the Wolf/Moose Study on Isle Royale - the longest study of any predator-prey system in the world - with lead researchers Rolf Peterson and John Vucetich.

The study has been going on since 1958 and recent advancements have landed the study in a recent edition of the journal "Ecology," Bump said.

Until now, the research results inform about the limits of human ability to predict and understand natural systems, the nature of predation and many particulars about why and how wolves and moose are the way they are.

What started as a side project, Bump said the scientists began looking to see if there was any soil response in terms of nutrients in carcass sites where wolves were killing moose.

The question of whether predators, like wolves, had any influence on ecosystem processes such as the distribution of nutrients, was largely unanswered before conducting this initially small study.

"It's surprising that it was," Bump said. "We found the hotspots of fertility given that the carcasses are so well utilized by wolves. They're cleaned up pretty well."

After that discovery, the scientists traced soils in the plants and saw that plants were a bit enriched with nitrogen, which is important for plants.

"My collaborators and I were able to take advantage of the long-term study's carcass base," Bump said.

Nearly 4,000 carcass sites recorded for Isle Royale over a 50-year term was used to show that wolves help determine hotspots of soil fertility, plant quality and microbial activity.

"Then we can explore the question, are the differences on the landscape where wolves are killing moose relative to where moose die from other causes," he said.

Wolves cluster carcasses in tight areas, he said.

"That carcass effect for the fertility and the biochemical changes that occurs at the carcass site is influenced spatially and temporally through the year," he said. "If wolves are causing it, wolves have influenced that."

Previously, it was not intuitive that a large wolf could be related to something on the ecosystem level.

"It's important to understand what's gained or lost with the healthy wolf population," Bump said. "If we're going to live with wolves successfully, it's important to know what is gained or lost."

As part of his research, Bump visited a few dozen carcass sites, documenting the soil effect and plant response.

"Once we understood the effect that occurs at a carcass site, then we can scale it up to the landscape level and say, 'Is this effect happening with any sort of pattern and is that pattern related to wolf prediction?'" Bump said.

And it is. There are areas of the landscape where wolves are killing moose and moose carcasses are hitting the ground at higher rates from other causes of death, such as starvation or disease and it's not always the same place over time.

"Some places on the island have been really hot for carcasses and turn cold and that's where the current state of research is," Bump said. "Why do some areas appear to be favorable and then shift to unfavorable?"

Scientists are left to wonder if this shift has to do with moose habitat selection, social dynamics of a single pack of wolves and changes in leadership - the behavioral ecology of the predator - or with competition among wolf pacts and the changes in numbers among pacts on the island.

Currently, the scientists plan to explore why the hotspots of fertility and carcass density seem to be patchy in one area and why some areas are tightly clustered and then not.

"I think the why of that may have to do with landscape changes and forest structure, moose habitat selection or the behavior or the wolves," he said. "I think it's important, in ecology in general, understanding patchiness as a major theme and what factors drive patchiness and to think that wolves can affect the patchiness of soil fertility is something new."

Also, when large predators like wolves affect ecosystem processes, like nutrient cycling, plant productivity or bio-mass, it's usually thought that they do so by limiting their prey populations.

"If wolves had an overall negative effect and can control moose populations, and less plants are being consumed by moose, then wolves, indirectly, release the plant population," Bump said. "All you have to have, for the effects we observed to occur, is a healthy wolf population and moose population on the landscape, and then you're going to have clustering of carcass sites over time."

To learn more about the Wolf/Moose Study, visit isleroyalewolf.org.

Stacey Kukkonen can be reached at skukkonen@mininggazette.com.