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Red alder trees can break through rocks to release nutrients

Red alder trees play an important role in promoting healthy forest ecosystems by tapping into nutrients that are locked in bedrock, such as calcium and phosphorus. According to a study from Oregon State University and the U.S. Geological Survey, this process speeds up the dissolution of rocks and makes more nutrients available for the surrounding plants and trees.

Study co-author Julie Pett-Ridge is a geochemist in OSU’s College of Agricultural Sciences. She explained that the research addresses the long-term implications of how nutrients make their way into ecosystems, which sustain their long-term growth and productivity and ultimately store carbon.

The study also provides new insight into how some trees can naturally fertilize forests, which is essential for natural ecosystems. In a process called nitrogen fixation, the trees convert atmospheric nitrogen into forms that can be utilized by other plants.

“Nitrogen mostly comes from the atmosphere, but more than 20 other nutrients mostly come from rock,” said Pett-Ridge. “We’ve established a connection between those two processes. Nitrogen-fixing trees, which we knew were special for how they bring in nitrogen from the atmosphere, also have a unique ability to accelerate the supply of rock-derived nutrients.”

The red alder is a deciduous tree that is native to western North America, but is closely related to other species of alder around the world. Alder tree species, including red alder, have the ability to release nitrogen into soil through nodules on their roots.

Study lead author Steven Perakis is an ecologist with the USGS. He said that, in a way, the red alder trees eat through the rocks.

“These trees not only can add nitrogen to ecosystems, they also can add all the other nutrients that forests require to grow and store carbon,” said Perakis. “That knowledge can contribute to the sustainability of forest practices in managed forests. Farmers figured out a long time ago that nutrients were essential for maintaining productivity. These processes take a little bit longer to show themselves in forests.”

The study is published in the journal Proceedings of the National Academy of Sciences.

By Chrissy Sexton, Staff Writer

Image Credit: Walter Siegmund

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