In addition to providing opportunities for recreation (like this cross-country ski trail at the Tanglewood 4-H Camp in Lincolnville), forests help to offset global warming by removing a key "greenhouse gas" from the atmosphere. 

Researchers: Forests play key role
in addressing world climate change  

By Andrew Kekacs

You'll see earlier ice-outs on Maine lakes, black flies arriving sooner in the spring, and birds lingering before heading south in the fall, according to Ivan Fernandez, a professor of plant, soil and environmental sciences at the University of Maine.

Temperatures will rise throughout the year, bringing a longer growing season. The gain will be partly offset by longer dry spells just before harvest. Despite the droughts, there will be slightly more rain throughout the year.

Global warming is real, it has arrived in Maine and scientists like Fernandez are looking at forests as one of the ways to address it.

Researchers say the changing climate is caused by an increase in carbon dioxide and other "greenhouse gases" in the Earth's atmosphere. The gases let in light but trap heat, serving as a transparent blanket that makes life possible on a planet surrounded by the frigid vacuum of space.

The concentration of carbon dioxide in the atmosphere has increased rapidly since humans began to use coal, petroleum and natural gas, which are formed from the remains of plants and animals that lived millions of years ago. When such fossil fuels are burned, the ancient carbon stored in them is released to the atmosphere as carbon dioxide. In essence, the transparent blanket gets thicker.

Fernandez said trees and other plants play an important role in the carbon cycle. Put simply, they use photosynthesis to turn carbon dioxide in the atmosphere into sugars that fuel their growth. Carbon is stored (or "sequestered") in the plants until one of three things happens:
a. They are eaten by other organisms (think of cows in a field), which break down the carbon into fuel and release it through breathing.
b. They die and decompose, sending carbon dioxide back to the atmosphere.
c. They are harvested for non-food products that may be used for days, years or centuries.

 

A simplified view of the carbon cycle. (Courtesy of The National
Center for Atmospheric Research) 

Forests store between 12 and 20 percent of the carbon dioxide released into the atmosphere of the Northeast each year.  "If you asked an engineer to design a machine that was solar powered, took carbon dioxide from the air and stored it in a solid form, it would be a tree," said John Hagan, director of the forest conservation program at the Manomet Center for Conservation Sciences in Topsham.

The removal of forests to make room for human settlements and farms has decreased the planet's capacity to store carbon in trees, however. According to some estimates, the amount of wooded land on Earth has fallen by half since the dawn of civilization some 8,000 years ago.

Hagan and other scientists are studying how to use remaining forests to remove the most carbon dioxide possible from the atmosphere. During the next 12 months, Manomet will be part of a research project looks at several wooded parcels -- from a large preserve to actively managed plantations -- to learn how much carbon can be sequestered over the long term under each management regime.

Hagan said forest preserves can store huge amounts of carbon, but over time they become fully mature. At that point, the amount of carbon taken up by the forest will roughly equal the amount released through the death and decay of trees, leaves and roots.

Forests that are actively managed for wood products can continually remove significant amounts of carbon from the atmosphere, he said, but a portion is released when the trees are harvested.  Some products made from the wood -- like furniture or shingles -- remain intact and store carbon for decades. Other products (for example, firewood or newspapers) are used up quickly and release carbon dioxide back to the atmosphere.

"Life-cycle analysis" of products made from wood is a basic focus of research, as scientists study the ability of forests to remove carbon from the atmosphere and sequester it in products with long life spans.

"We need to know what every product is, for all the wood that comes off those lands, and all the energy costs to make those products," he said. "It's a big accounting problem."