Twenty years of change in a northern hardwood forest

Forests undisturbed by logging play a vital role in our understanding and m anagement of forest ecosystems. The Bowl Research Natural Area (RNA) in the White Mountains of New Hampshire is such a forest. The Bowl RNA and an adj acent area known to have been logged in 1888 were inventoried in 1974 and 1 994. The mean basal area of the mixed forest below an elevation of 915 m in the RNA increased from 29 m(2) ha(-1) in 1974 to 32 m(2) ha(-1) in 1994. T here was no significant difference in basal areas of the RNA forest and the adjacent forest cut in 1888, in either the 1974 or 1994 sampling. Beech wa s the most numerous species in all areas of the Bowl followed by spruce-fir . Yellow birch had the greatest basal area followed by spruce-fir and beech . Results from this study indicate that northern hardwood forests of severa l hundred hectares can be expected to maintain average basal areas of ca. 3 0 m(2) ha(-1) and above-ground biomass of 150-250 Mg ha(-1). Comparisons of the Bowl and nearby Hubbard Brook Experimental Forest indicate that, withi n 100 years following heavy forest cutting, the northern hardwood forest ca n be expected to regrow to the point where numbers of stems, basal-area, an d biomass will be comparable with old-growth forests. (C) 1999 Elsevier Sci ence B.V. All rights reserved.