Climate Change: A Threat to Life on Earth
By Michael Daley
A Question: What is the connection between a beloved Robert Frost poem, a parcel of wildlife conservation land in rural Vermont and present-day climate change?
The Answer: Lasell College
In 1925, Lasell acquired a large tract of forest near the White River in Vermont. As the story is told in a 1932 Leaves article, "Lasell lacked her quota of pupils, and a certain gentleman lacked the money to send his granddaughters here. A trade was arranged-land for education." Following that exchange, Lasell acquired additional land and planned to engage in forestry operations as a source of revenue.
Millions of trees were planted. The operation was successful, but the retirement of a key forester in the 1950s prompted a discussion of the future of the Lasell Forest. Soon after, the Forest was gifted, to be conserved, to both the State of Vermont and the Green Mountain National Forest.
After 30 years of Lasell stewardship, much of the donated land was annexed to the Les Newell Wildlife Management Area (named for the forester who managed he land) with parcels fragmented and spread out over four towns: Barnard, Bridgewater, Stockbridge and Sherburne. This land is found in a remote area of Vermont with thriving wildlife. Stands of hemlock, red maple, sugar maple, birch, beech, balsam fir and red spruce dominate the landscape. The animal diversity is also high with species such as moose, white-tailed deer, bobcats, coyotes and black bears. The forests and wetlands support many species of amphibians and a wide range of songbirds. Healthy streams run through the land with populations of brook and rainbow trout. In short, it is pristine and special.
While the land was donated to the State of Vermont for conservation, many changes to the forests and wildlife are imminent due to the threat of climate change. Climate change has already begun to impact Northeastern forests; the predicted changes in the coming decades are drastic. The two major changes that models predict in the Northeast are warmer temperatures, particularly in the winter, and less frequent, but more intense precipitation events. Combined, these changes will alter a long list of natural ecosystem processes including evapotranspiration, soil respiration, photosynthesis and nutrient cycling and disrupt the ecology of the entire region.
Every species has an optimal range and a tolerance range for precipitation and temperature. Over the next 50 years, as temperatures and periods of drought increase, we will see many changes to the Northeast forests. For example, spruce and fir trees will struggle in lower-elevation areas such as the Newell Wildlife Management Area, the former Lasell Forest. Oak trees are better competitors in warmer and dryer areas and will slowly replace spruce and fir trees. Similarly, climate change models predict a decline in the northern hardwood species such as sugar maple, yellow birch and American beech-species that help bring vibrant color to Vermont's fall foliage.
We can also expect the decline of hemlock stands in the Northeast as a result of climate change. Hemlock trees are threatened by hemlock woolly adelgid, an invasive pest. The infestation, widespread in Connecticut and Massachusetts, is not yet severe in Vermont and New Hampshire where cold winter temperatures significantly reduce the population of the pest.
As winter temperatures increase, as is predicted, we expect invasive pests that are cold-limited to expand north. The loss of hemlock forests raises concern for other organisms, as well. As hemlock stands die, hardwood species replace the declining hemlocks. My research at Harvard Forest found that transpiration rates from hemlock trees is nearly half that of many hardwood species. The transition from hemlock to hardwood will alter soil moisture and flow in small streams and have a direct impact on amphibian and fish populations, including trout.
Wildlife species in the Northeast will also shift as a result of climate change. The moose population found in the Newell Area will likely decline as warmer temperatures begin to limit the southern range of the species. As the composition of tree species is predicted to change, we also expect a shift in bird species. The changes in tree composition and habitat structure will alter the bird species associated with the forest.
These are just a few examples of changes predicted in the Northeastern forests. While humans cannot sense a small change in temperature, an annual change by just a few degrees has a large impact on ecosystem processes. These small changes set in motion feedback loops that quickly result in significant alterations to ecosystems.
In 1941, Vermont poet Robert Frost gave a reading at Lasell. Afterwards, he and then-President Guy Winslow, a Vermont native and ardent lover of the woods, together examined a portion of a witness tree from the Lasell Forest. A year later, Frost's celebrated volume of poems, A Witness Tree, went on to win him a fourth Pulitzer Prize. Included in the volume, "Come In," published in Frost's handwriting for the first time and dedicated to the Lasell Class of 1941.
Just as Robert Frost once found artistic inspiration in the Lasell Forest, his poetry lives on as a historical record of what once thrived there. The Newell Wildlife Management Area will remain, but the trees and wildlife within will experience substantial shifts if the world does not act soon to reverse the effects of climate change.
Michael Daley, PhD, is associate professor of Environmental Science at Lasell College. A forest ecologist with interests in global change biology, Daley's research examines the interaction of vegetation and its physical environment. In 2004, he was awarded a National Science Foundation fellowship to pursue research on the impact of the invasive hemlock wooly adelgid pest on New England forests.