Why Every Forest Matters
When it comes to forests, we tend to prize “old growth” survivors over younger “second growth” woodlands. But in two new studies, Harvard University scientists have found that New England’s “middle-aged” forests are important natural assets for the health of local communities, the region, and even the world.
In research published this week in The Journal of the Torrey Botanical Society, scientists found that the forests of New England soak up enough carbon dioxide every year to account for half the region’s planet-warming CO2 emissions.
In 2011, the latest year for which data is available, the six New England states produced 149.1 million metric tons of carbon dioxide, according to the federal Energy Information Agency.
The researchers examined the growth of more than 6,000 trees—including red oak, red maple, and yellow beech—for several decades on a single seven-acre plot. The unusually large and detailed trove of information about this stand of forest has been collected for 42 years at Harvard Forest, a 3,700-acre, 110-year-old research forest in western Massachusetts.
The trees are continuing to grow, suggesting that the forest’s carbon storage capacity will continue to go up as well.
In the other study, published this week in the Journal of Applied Ecology, researchers found an increasing number of forest “hotspots” in Massachusetts between 2001 and 2011: stands that are providing five or more valuable natural services to society, including carbon storage, recreation, water filtering, flood protection, and wildlife habitat.
They also showed why scale matters in assessing how and why forest is a hot spot: An intact forest that seems to be a big park to local residents may be revealed as an important source of clean water for millions when the view is pulled back to encompass a bigger region.
At the local level, services like flood prevention, water filtration, and wildlife habitat are degraded in locations where forests are fragmented or logged. But perversely, these drivers also render the remaining forests conservation-worthy hot spots and lead to more outdoor recreation opportunities, which increased by more than 13 percent in Massachusetts from 2001 to 2011.
New housing and commercial construction on the edge of Boston has reduced the state’s eastern forest cover, the study noted. “Over the past ten years, urban development has increased by more than 6 percent, at the expense of forests and agricultural lands,” study coauthor Jonathan Thompson, an ecologist at Harvard Forest, said in a statement. “When we lose intact forests, we lose stable flows of clean water, climate regulation, recreation opportunities, and wildlife habitat. The remaining forest is left to pick up the slack.”
Still, the study’s authors urged natural resource managers and environmentalists to be wary of not seeing the forests for the trees.
“While ecosystem service hotspots are valuable targets for conservation, more are not necessarily better,” they wrote, “since hotspot proliferation can reflect the bifurcation of the landscape” into forests that provide multiple natural services and developed areas that take more than they can give back.