WINTER HARBOR — The years and decades to come could bring complex changes to New England’s forests, according to scientists.
A new 246-page report issued by the United States Forest Service, a division of the Department of Agriculture, says that changing climate in New England will lead to milder winters and more precipitation. In turn, some trees that are culturally and economically important could be threatened by changing weather conditions.
Scientists used a range of possible future climates to predict what might happen to the trees, and presented their data to a multidisciplinary panel of scientists and “natural resource professionals.” They looked at a 53-million-acre area, 75 percent of which is made up of trees.
Among the findings was the fact that between 1901 and 2011, the average annual temperature rose 2.4 degrees F across all of New England, “with even greater warming during winter.”
“Precipitation patterns also changed during this time, with a slight trend toward greater annual precipitation and a substantial increase in extreme precipitation events,” the report reads.
Looking ahead to 2100, the report predicts another increase of 3 to 8 degrees F and increased rain and snow during fall and winter.
According to Nick Fisichelli, the director of forest ecology at Schoodic Institute, a wide range of models were used. He was one of 30 scientists who co-authored the report. The study began between two and three years ago.
That range in temperature estimates, he said, comes from uncertainty about how much greenhouse gases like carbon dioxide will continue to be in the atmosphere over the next 80 years.
New technologies or regulations, according to Fisichelli, could limit or scale back the levels of greenhouse gases. But no matter what, the region is going to get warmer.
“All the models suggest continued warming — that’s across the board,” he said.
The study comes in the midst of a harsh winter in Maine, making climate change as it’s been discussed in the past feel far away. But ice in Greenland, Alaska and the Arctic Circle continues to recede. Ocean temperatures have risen, and the acidity of their waters has increased. Climate disasters pressure human infrastructure to breaking points: Cape Town, South Africa is fast-approaching an expected “Day Zero” in April, when the city will exhaust its water supplies. Heat waves, droughts and wildfires have plagued California in recent years.
Scientists predict Maine and forests throughout New England will get warmer and wetter.
“Conventional wisdom is that wet areas are going to get wetter and dry areas are going to get drier,” Fisichelli said.
He explained that as temperatures increase, things move faster. For plants and trees, that means photosynthesis can increase, and respiration goes up. Plants start to make food quickly, and therefore eat quickly — all increasing stress on their systems.
Spruce and fir are both tree species that have trouble keeping up, and are likely to decrease. Other trees, like birch, black cherry, maple and oak all do well in these conditions and may adapt.
Fisichelli said the dynamics of the forest are likely to change, then, and it’s difficult to know what that might look like. In an area that’s dependent on forests for tourism, conservation, timber harvesting and recreation, any changes in the forest ecosystem could be significant. Forests also help clean the air and provide habitat for wildlife. They reduce flooding by slowing the flow of water.
“We ask a whole lot of our forests; we expect them to do everything,” he said.
It’s nailing down what those changes might be — and how they’ll affect activities — that’s the difficult part. Other factors play a role. Fisichelli said coastal forests fare differently than inland ones. Trees on a south-facing slope may have a different response to the changes than other trees within the same forest.
“There will be winners and losers, and we’re just trying to figure out what those species might be,” he said.
Other complicating factors could be the spread of disease and pests. Some species such as fungi thrive in wet conditions; insects can do well in hot conditions. Both of these pose threats to trees. But Fisichelli also said animals such as deer can affect how trees grow, since they favor certain species over others.
Forests aren’t going anywhere, he emphasized, but the question is what they will look like. Forest managers will play a key role in helping shape the direction these future forests take. They could plant trees that might do well in warmer temperatures — broadleaf, hardwood trees that might already exist here but are at their northern edge.
Reducing dependency on any one species is key, Fisichelli said. Therefore, healthier forests might be more diverse as the weather conditions change.