Long-term temporal dynamics of the Duke Forest

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  • March 22, 2019
Creator
  • Payne, Christopher
    • Affiliation: College of Arts and Sciences, Curriculum in Environment and Ecology
Abstract
  • In this dissertation, I describe a series of permanent sample plots in the North Carolina Piedmont used to examine near-century forest processes and to evaluate how observed trends can inform existing conceptual models. Specifically, 80 years of tree growth and forest composition were recorded across all succession phases in a series of successional Pinus taeda stands and second-growth Quercus-Carya and Liriodendron-Liquidambar hardwood stands in the Duke Forest. I use these long-term data to scrutinize classical theories of community dynamics and growth trends in Piedmont forests that have served as a model system for successional research for nearly 100 years. Specifically, using a suite of multivariate statistics I examine whether old-field pine forests have succeeded toward putative climax compositions or whether deviations in successional trajectories have occurred owing to shifts in species composition and disturbance events. I additionally examine whether biomass of successional stands can be predicted based on canopy mortality and lags in regeneration and whether growth rates of later-stage forests have increased more than expected over the last century. 80-year biomass and growth trends in successional plots confirm the importance of canopy density and mortality in driving these patterns, but lag patterns in post-hurricane regeneration are not yet formally discernible. In contrast, second-growth hardwood plots demonstrate consistent biomass accumulation and continued increases in growth rate, despite having achieved biomass levels found in more static old-growth forests. Community analyses indicate that successional stands experienced shifting compositional trajectories that were accelerated by Hurricane Fran and resulted in replacement of upland-associated hardwood species (e.g., Cornus florida) with species associated with more mesic stands (e.g., Acer rubrum, Liquidambar styraciflua, and Fagus grandifolia). A similar replacement of putative climax species (e.g., Quercus alba) with A. rubrum occurred in understories of late-successional hardwood stands. In contrast with accepted successional models, these results are in line with mounting evidence of unanticipated and less predictable forest dynamics over the last century. Such changes could be the result of changing climate patterns or anthropogenic impacts. Regardless, more mechanistic experiments must be developed to determine the cause of these seemingly-widespread patterns to better inform global change and forestry models.
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  • In Copyright
Advisor
  • Peet, Robert
  • Peart, David
  • Urban, Dean
  • White, Peter
  • Song, Conghe
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2018
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file details Payne_unc_0153D_18057.pdf 2019-04-12 Public Download
file details Supplemental Appendices S1-S3. S1 contains PSP data files, S2 contains MAP data files, and S3 contains source code for MultiEDA. 2019-04-12 Public Download