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Regeneration stage stand development in upland Appalachian Forests.
Fei, Songlin*,1, Steiner, Kim1, Finley, James1, McDill, Marc1, Gould, Peter1, 1 The Pennsylvania State University, University Park, PA
ABSTRACT- Field measurements of 61 upland forest stands in Pennsylvania were performed on 6370 subplots during 1996 - 2002. All the stands were measured one year prior to harvest, 41 stands have been re-measured one year after harvest, 13 stands have been again re-measured 4 years after harvest, and 5 stands have been re-measured 5 years after harvest. In addition, 15 stands with the age of 6 - 10 years after clearcutting were measured in 2001 - 2002. Regeneration size and density were used in this study to analyze stand development patterns and identify measures of regeneration success. Compared to one year before harvest, 22 percent of the regeneration cohorts had increased in both density and height one year after harvest, 37 percent had increased in height but decreased in density, 12 percent had increased in density but decreased in mean height, while 29 percent had decrease both in density and height. At four years after harvest, not surprisingly, all cohorts had increased in height, 38 percent increased in density, and 62 percent had decreased in density compared to one year after harvest. Stem mortality was observed in some 5-year-old stands, which indicates that the stem exclusion stage can occur as early as 5 years after harvest. Dead stems represented up to 51 percent of the total density in some subplots. A seedling size-density relationship was statistically estimated for these stands. The frontier exhibits a curvilinear relationship between log-scaled maximum density and quadratic mean height. Minimum seeding density for full site occupancy (B-level stocking) was also modeled based upon best-fit estimates of tree area ratios. Knowledge of regeneration development and potential biological frontiers are prerequisites for the development of ecologically sound silvicultural management prescriptions and realistic predictions.
Key words: Stem Exclusion, Regeneration Development, Size-Density Relationship