The report also states that, in the absence of an insulating snow pack, exposed soils are more susceptible to freezing, which damages tree roots. As a result, there has been an increase in mortality. The study concludes, as well, that sap yields have been reduced, apparently as a result of warming winters.
A 2002 Environmental Protection Agency Climate Action Report notes that “climate change is likely to cause long-term shifts in forest species, such as sugar maples, moving north out of the country.” And a study conducted by the USFS, which looked at on-the-ground movement based on latitude, not computer-modeled simulations, confirms the northward movement of 40 major tree species growing in 30 eastern states.
The results of that study, which looked at 15 northern species, 15 southern species and 10 species found in both regions, were published in 2009 in the journal Forest Ecology and Management and determined that 11 of the 15 northern species have shifted north by latitude. When commenting about the study, Chris Woodall of the Forest Service’s Northern Research Station in St. Paul, Minn., said, “This is no longer conjecture.”
Maples, like poplars, ashes, and several other deciduous species, have seeds that are light enough to be dispersed over several miles by wind. As such, they can expand their range comparatively easily and quickly. As sugar maples migrate north (and to higher elevations), those left behind in warmer environments will eventually be displaced by better adapted, faster growing species, like oak and hickory.
Migration of tree species is nothing new. For example, in response to changes in climate toward the end of the last ice age, forest communities gradually migrated northward in the wake of receding glaciers. The current northern migration, however, appears to be occurring at an unprecedented rate.
Whatever the cause, the effects of a changing climate (e.g. heat stress, decreased soil moisture) are likely to significantly impact many of our commonly occurring tree species. And maple production is not the only agricultural industry likely to be adversely affected as climates shift.
But that’s another story.
Richard L. Gast, Extension program educator II, Horticulture, Natural Resources, Energy; agriculture programs assistant, Cornell Cooperative Extension of Franklin County, 355 West Main St., Suite 150, Malone, 12953. Call 483-7403, fax 483-6214 or email firstname.lastname@example.org.