Has Climate Affected Tree Species Distribution in New England?
Due to prospective responses to a changing/warming climate, Forest Service researchers are seeking evidence that New England tree species are moving higher in elevation and moving further north to seek a cooler environment. Computer modeling efforts try to simulate such changes but does long-term, reliable, ground-based information exist to test such models? In 1931-32, a series of about 500 one-quarter-acre cruise plots were established on the Bartlett Experimental Forest, N.H., from the Saco River valley bottom to top of the Haystack Mountains, an elevational range of 650 to nearly 3,000 feet. These plots have been remeasured periodically over the years; new remeasurement is underway. Comparisons of species’ elevations show no noticeable changes. Eastern hemlock, a species limited in elevation by climate, showed no consistent change in elevational distribution between 1932 and 2003, although the percent composition of this vigorous species increased dramatically. A separate analysis of climate-sensitive red spruce on the higher-elevation cruise plots shows the species is stable or increasing. Will things change in the future? Maybe, but 70 years of detailed records show no obvious response at the present time.