Upland old-field succession in southeastern New Hampshire

A 22-site chronosequence was used to study old-field successional communities in Transition Hardwood forests of Durham, NH. Sites ranged from recently abandoned fields to hemlock forests greater than 200 years old. Trees, shrubs, and herbs were sampled in nested quadrats, and importance values were calculated. Increment borings were used to determine site ages. Five woody community types were identified using cluster analysis and ordination: 1) Gray Dogwood and 2) Juniper-Blackberry-Sweetfern (both early-successional, 14-23 years since abandonment), 3) White Pine and 4) Oak-Viburnum (both stud-successional, 50-150 years since abandonment), and 5) Hemlock (late-successional, 100-200+years since abandonment). Six herb stratum associations were found: 1) Kentucky Bluegrass and 2) Goldenrod-Dewberry-Buckthorn (both early-successional), and 3) Pennsylvania Sedge, 4) Wild Sarsaparilla, 5) Canada Mayflower, and 6) Canada Yew (all mid-late successional). Photosynthetically active radiation (PAR) declined exponentially over the 200-year chronosequence, and the temporal importance of woody species in the understory was associated with particular forest floor light levels. Actual succession at individual sites with similar soils may also be modified by previous land-use history, differential seed availability, and post-agricultural disturbance.