News Release

Aged Polish forest plots teach new ecosystem lessons

Peer-Reviewed Publication

Texas A&M AgriLife Communications



Dr. Mark Tjoelker, far left, works along other U.S. and Polish researchers in a 30-year-old forest near the village of Siemianice in western Poland.

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COLLEGE STATION -- A little-known acreage of trees in Poland planted in the late- 1960s has become a new teaching ground on biodiversity for a team of U.S. researchers. Though planted orchard-style over about 10 acres, the 14 different species of trees have at their bases as many different environments.

And that has scientists wondering how. How could plots of trees planted side by side in the same soil and subjected to the same climate over three decades with almost no human intervention cultivate such vastly different plant species -- and even soil acidity -- beneath them?

"Understanding how a tree species influences the ecosystem, or biodiversity, could be helpful in the long-term for managing forests," Dr. Mark Tjoelker, Texas Agricultural Experiment Station forest scientist, said. "It could help foresters know what the best mix of tree species would be to manage biodiversity."

What makes this stand of trees unique is that they have lived segregated but side by side for more than 30 years near the village of Siemianice in western Poland.

"The stands of trees are old enough now to see that they have changed in time," said Tjoelker. "The birch plot has grass and forbs underneath; the spruce a dark, thicker floor. There are many species of mushrooms in the forest, but they are segregated by the type of tree under which they grow."

Simply calling it "a common garden study of 14 temperate tree species," U.S. researchers are collaborating with the Polish Academy of Sciences to see if leaf and root traits of the trees can be linked to the ecosystem structure and function. Tjoelker will study physiology of the trees in his part of the three-year study under the National Science Foundation. He's teamed with fellow researchers from the University of Minnesota, Penn State University and the University of California-Santa Barbara. The forest is managed by the August Cieszkowski Agricultural University of Poznan.

"Plants have long been considered key controls of ecosystem functioning," the researchers explained, noting that plants can influence such elements as nutrient cycling, decomposition and productivity.

The difference, Tjoelker pointed out, is that studies until now have compared species where it would have been difficult to separate the effects of different climates, soils or tree age from the vegetation under the trees. Plus, the unique planting design in which only one tree species was planted in each plot but all of them side by side, gives scientists a rare chance to find what factor most may influence changes in the biodiversity of the ecosystem.

"The beauty of this planting is that it was replicated," Tjoelker said. "That is very unique, that someone had the foresight to plant the trees in monoculture stands gives us an excellent opportunity for this study."

Additionally, one of the team members specializes in root systems, Tjoelker said, so the species stands will be observed underground using small cameras inserted in tubes to see how the trees have grown underground.

"The fine roots, which grow every year from the main roots, are as important to trees as new foliage is," Tjoelker said. "Yet, we as foresters know less about that than other areas of tree growth."

He said the team also will consider decomposition of the forest floor litter and the pH of the soil which has been shown in preliminary tests to have changed among the various plots of the past 30 years. Results from the study are expected by 2005, Tjoelker said, but the researchers believe the Polish planting could provide information on a variety of issues for years to come.

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