PS 64-99 - A comparison of presettlement and modern forest composition in central New Hampshire

Thursday, August 11, 2011
Exhibit Hall 3, Austin Convention Center
Matthew A. Vadeboncoeur, Earth Systems Research Center, University of New Hampshire, Durham, NH, Steven P. Hamburg, Environmental Defense Fund, New York, NY, Charles V. Cogbill, Plainfield, VT and Wendy Y. Sugimura, Brown University

The tree species composition of northern New England is the product of natural processes, human disturbances, and a changing climate.  To understand interactions among these influences in a complex landscape, it is necessary to understand the composition of the forests before European settlement and today across the same landscape.  Because forest composition varies with elevation, we derived elevation data for each of 2,529 trees mapped by early land surveys in central New Hampshire, and compared these data with modern forest composition data from the USFS Forest Inventory and Analysis program, and from numerous permanent plots with different land-use histories. 


Dominant (>20 cm dbh) spruce and beech are much less abundant today at all elevations than they were in the presettlement forest, while maples and birches have increased at most elevations.  Loss of beech has been particularly dramatic below 500 m, and increases in birch above 800 m. The elevation distributions of fir, hemlock, pines, and oaks appear to have changed little, though pines and oaks have increased in abundance somewhat.  Land-use history (small-scale agriculture below 500 m and cutting of various intensities at all elevations) is likely the primary explanation for these shifts, though climate change is also an important factor for some. A clearer understanding of the composition of presettlement forests improves our ability to separate the relative importance of natural and human-driven influences on the species composition of today’s forests.

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