Climate Change and Acid Rain Could Be Actually Good for Forests

by Hannah Punitha on Oct 27 2008 5:06 PM

A research spanning 20 years has determined that climate change and acid rain could actually be good for forests.

The research was undertaken by scientists at Michigan Technological University's School of Forest Resources and Environmental Science in the northern hardwood forests of Michigan.

The team reached a surprising conclusion that moderate increases in temperature and nitrogen from atmospheric pollution actually improve forest productivity.

The researchers have been monitoring and measuring the temperature, moisture levels and nitrogen deposited by acid rain or varying levels of experimental nitrogen at four forest sites ranging from northwestern to southern Michigan since 1987.

They found that the trees grow faster at higher temperatures and store more carbon at greater concentrations of nitrogen, a chemical constituent of acid rain, providing there is sufficient moisture.

It may well be that increasing temperature and nitrogen deposition are good things, up to a point, said Andrew Burton, an associate professor at Michigan Tech and head of the National Institute for Climatic Change Research's Midwestern Regional Center.

The rise in temperature is extending the growing season, explained Burton.

So far, Burton and colleagues have measured 10 to 11-day longer growing seasons. Our growing season isn't that long in the first place. So, 10 or 11 days is significant, said Burton.

A longer growing season could benefit the timber industry, enabling them to harvest more wood.

Now that woody biomass is being investigated as an alternative energy source by Michigan Tech and others, increased forest productivity could become a critical factor.

The research, which started out as an acid rain study in 1987, has grown into one of the longest continuous research studies supported by the National Science Foundation.

Burton and his fellow researchers, Don Zak at the University of Michigan and Kurt Pregitzer at the University of Nevada-Reno, want to discover if the increased annual growth of the forests is offset by an increase in tree mortality.

They also will examine whether the woody debris on the forest floor will decompose more slowly as nitrogen levels are increased, further increasing the ecosystem's ability to store carbon.

Burton calls the new work "a window into the future, an opportunity to see if there is a tipping point beyond which increased nitrogen harms rather than helps the forests.