Date of Award

5-2006

Level of Access Assigned by Author

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Forest Resources

Advisor

Robert G. Wagner

Second Committee Member

Robert S. Seymour

Third Committee Member

Malcolm L. Hunter, Jr.

Abstract

Research plots in many long-term studies of forest ecosystems often cannot be used for spatial modeling because of their small scale and nested inventory design. This has been unfortunate as these plots represent some of the best records of structural development as affected by forest management. I developed methodologies to reconstruct both tree height growth and spatial pattern in these types of plots from historical inventory records and stem-mapped data, and then retrospectively investigated 3-dimensional structural development as affected by five silvicultural and harvesting treatments (unmanaged natural area, commercial clearcut, fixed-diameter limit, 5-year selection, and 3-stage shelterwood— with and without precommercial thinning) in a long-term, USDA Forest Service study in Bradley, ME. In order to capture site variation and account for the hierarchical inventory design, mixed-effects, nonlinear heightdiameter models were developed for the nine most common tree species in 50 stemmapped plots: Abies balsamea (L.) Mill., Acer rubrum L., Betula papyrifera Marsh., B. populifolia Marsh., Picea rubens Sarg., P. mariana (Mill.) B.S.P., Pinus strobus L., Populus tremuloides Michx., and Tsuga canadensis (L.) Carr. Height-diameter models for the remaining species were fit with generalized nonlinear least squares. A morphing algorithmn was developed and then tested on both simulated and actual point patterns, to scale the spatial pattern from nested, sapling subplots (0.020 ha) to the scale of the larger tree plots (0.081 ha). Differences in spatial pattern, species mingling, height differentiation, and relative stand complexity index (rSCI) were compared among treatments. Regeneration events, whether induced through natural stand breakup or by harvesting, increased aggregation in spatial pattern and reduced species mingling. This pattern was heightened when treatments shifted species composition more towards hardwood species. Variation in height differentiation and rSCI was generally highest in the natural areas and 5-year selection compartments, intermediate in commercial clearcut and fixed diameter-limit compartments, and lowest in 3-stage shelterwood compartments. Divergence in spatial structure between the two natural areas reflects natural stand development within this forest and is an appropriate benchmark for management. The reconstruction model developed here can be applied to other long-term studies where the lengthy temporal scale can substitute for small spatial scale.

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