Dec 20 2018
Forests around the world are on a fast food diet of carbon dioxide, which is presently causing them to grow faster. But a scientist at West Virginia University, together with an international team of researchers, discovers evidence indicating that forest growth may soon peak as the trees exhaust nitrogen in the soil over prolonged growing seasons.
Brenden McNeil, associate professor of geography at West Virginia University, measures the girth of a sugar maple on West Virginia Land Trust property as part of his research. (Credit: WVU’s Eberly College of Arts and Sciences)
West Virginia’s wildlands are a “canary in the coal mine for climate change” because of the forests’ biodiversity, which, together with rich soils and plentiful rainfall, make them among the sturdiest forests globally, according to Brenden McNeil, an associate professor of geography at WVU’s Eberly College of Arts and Sciences. The state’s forests have been robust against a barrage of logging and acid rain in the 19th and 20th centuries but are currently showing symptoms of deteriorating health because of climate change.
Like humans, trees too need to have more than one thing in their diets, McNeil said. But the proliferation of carbon dioxide is force-feeding them the one thing they use most. McNeil said the challenge is to reinstate a balanced diet for forests by strictly decreasing or ending altogether the use of fossil fuels.
“There’s more carbon dioxide in the atmosphere, and that’s the raw material that trees need to convert to sugar, which they use to grow,” he said. “What is profound is that as all the plants grow faster; they’re slowing down climate change.” But, as he explained, “the plants of the world can’t do that forever.”
In a paper published in Nature Ecology and Evolution, McNeil and approximately 40 international scientists state that most terrestrial ecosystems are seeing decreasing nitrogen isotopes in foliage on a global scale. It increases global support to a 2017 paper where McNeil was part of another team that used nitrogen isotopes in tree rings to discover evidence for decreasing nitrogen in forests across the United States. The majority of the world is still “greening” in response to climate change, but depleting nitrogen means future growth will become unhealthier and out of balance, and trees will have to work harder to extract the nitrogen, McNeil continued.
His current work, conducted with a team of WVU Honors College undergraduate students, graduate students, as well as Edward Brzostek in the Department of Biology, and Nicolas Zegre in the Davis College of Agriculture, Natural Resources and Design, is inspecting the responses of West Virginia forests to climate change.
In an area measuring about the size of six football fields in the Summit Bechtel Reserve Scout Camp, this research team is taking a massive tree census. Scouts also take part in measuring the trees in this “citizen-scientist” project dedicated to mapping 15,000 trees relative to a completed GPS survey grid. This census will give a baseline for long-term study of tree growth in a changed climate.
Cameras in the tree canopy, millions of laser beams searching the trees’ structure and satellite imagery are also aiding McNeil and the research team to comprehend how a forest can sustain productivity and how various species adapt to reduced nitrogen and increased carbon dioxide. The team is taking in account everything from the angles of leaves to the depth and breadth of a tree’s roots to nutrient and water availability.
All these efforts measuring forests aim to respond to a core question: For how long will forests decelerate climate change, and help us avoid the approaching costs of adapting to a more disordered climate?
It’s going to cost us a lot more if we do not change now. As described by the recent Fourth National Climate Assessment, increasing carbon dioxide in the atmosphere is changing our global climate in ways that are costly to our economy.
Brenden McNeil, Associate Professor of Geography, WVU’s Eberly College of Arts and Sciences.
McNeil said making moderately small investments to diminish dependence on fossil fuels is similar to paying life insurance premiums. The result of not making the investments currently will be the risk of losing the stability of the natural systems that humans rely on for water, food, and protection against diseases and extreme weather conditions.
Although McNeil’s and the other scientists’ predictions sound terrible, he believes the planet and humanity will endure, but in a much-different world both economically and ecologically.
He said as the world transitions from fossil fuels to more environmentally friendly sources of energy like wind and solar, the cost-benefit ratio will recover.
The solutions are here. It just takes the will to enact them.
Brenden McNeil, Associate Professor of Geography, WVU’s Eberly College of Arts and Sciences.