By Star Childs

With all the recent hype and hoopla about human-induced global climate change, I am often asked what changes in the forested landscape are we seeing that might be attributed to human releases of greenhouse gasses?  Right now, very little. But forest change occurs over centuries. Paleo-pollen studies done in Tobey Bog reveal that more than 8,000 years ago, boreal spruce and fir once cloaked the hills of Norfolk and only gradually gave way to our more characteristic mix of oak, pine, hemlock and northern hardwoods. That will undoubtedly continue, given that the warming trend predicted in climatic models will not quickly reverse.

Forests thrive on carbon dioxide, and young vigorous trees will happily take up the gas to manufacture the sugars and starches they need to grow. In addition, excess nitrogen oxide released from combustion sources ends up in the forest soils acting like fertilizers to enhance growth. Much of this nitrogen is lost through dissolution with from rain and storm runoff. Studies on Great Mountain Forest and elsewhere in the northeast have been documenting the loss of critical trace minerals in the soils through acidic deposition and leaching caused by a host of fossil-fueled combustion gases. Early results from a number of field research sites indicate that the trend in net loss of soil calcium is a serious risk for New England forests.  Calcium is essential to enable trees to capture and move nutrients into their root systems and throughout their tissues.  This calcium loss could have far more serious consequences for the health of our forests than gradual temperature rise.

Temperature changes, however, will continue to have health effects on the forest. The most notable involve bizarre shifts from unseasonably warm temperatures to arctic cold. Winter injury and dieback from sudden freezes after a mid-winter thaw has been documented, particularly on older trees and on ornamental trees and shrubs. Sugar maple is especially prone to these stresses and according to Canadian and NASA-based computer climate models; the species is projected to lose more ground in the northeast, eventually disappearing entirely from the New England landscape. Such a loss has ramifications for the tourist industry, to say nothing of the maple syrup producers and the lumbermen. The double whammy is that maples are especially dependent on soils, which are relatively rich in calcium. And Also, their leaves are more sensitive to smog-related ozone gas, which is predicted to increase. All in all, the picture does not look bright for our maple forests unless we really come to grips with fossil-fuel emissions.

Finally, one forest observation we can make with some certainty is that the insidious wood and deer tick populations have increased everywhere. A warming of the climate regime, burgeoning deer and mouse populations, cessation of the use of fire in land management, and the spread of invasive shrub species have played a role in the emergence of this problem. Managing the forested landscape in expectation of change is all that we can really do, but manage it we must. Meanwhile, be sure to check for ticks when you come in from the woods!