SIMULATED CLIMATE CHANGE ALTERS PHENOLOGY, COMPOSITION, AND STRUCTURE OF POST-HARVEST VEGETATION COMMUNITIES

Open Access
Author:
Rollinson, Christine
Graduate Program:
Ecology
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 27, 2010
Committee Members:
  • Margot Wilkinson Kaye, Thesis Advisor
Keywords:
  • phenology
  • climate change
  • forest harvest
  • community composition
  • climate experiment
Abstract:
Models predict that climate change may lead to altered forest community composition as southern species are able to successfully migrate northward. Forest harvesting could facilitate climate-related species migration by creating conditions that favor the establishment of new species or result. My research investigated the effects of simulated climate change on plant community composition, structure, and phenology in a 2007 mixed hardwood clear cut. In 2009, I conducted 22 biweekly vegetation inventories in a two-factorial randomized block design experiment with treatment factors of 2˚ air temperature warming and 20% increased precipitation, added weekly. I measured the impacts of our climate treatments on species composition, percent cover, leaf area index (LAI) and phenology. I used permutation multivariate analysis of variance (PerMANOVA) on the average cover of observed species over the entire season to assess the relationship between community composition and simulated climate change treatments. LAI and percent cover of the entire community and of different growth forms were analyzed using repeated measures ANOVA while community biodiversity, species richness, and phenological events were assessed using standard ANOVA for different growth forms. The overall and herbaceous community composition was influenced by water treatments (p = 0.05 for both) while the woody community responded strongly to the interaction of warming and precipitation (p = 0.03). Woody community analysis using stem abundance showed a strong reaction to warming alone (p = 0.005) and potential canopy species composition may also be affected by a warming*precipitation interaction (p = 0.056). In general, Shannon-Weiner biodiversity, evenness, and total or growth form species richness were not affected by our treatments. During peak growing season, forb cover was lowered by precipitation treatment and woody vegetation increased as a result of warming treatment. Total cover was generally lowered by a the interaction of warming and precipitation. Percent cover of all groups during the entire growing season was affected warming and precipitation treatments, but the direction of effects was highly varied. Large tree cover and LAI were higher in the spring in warmed treatments. During this time period, the average day of leaf out on canopy tree species and tall forbs and the date of flowering for short forbs were advanced by experimental warming and may be the driving factors of increased spring LAI. Our results indicated that young post-harvest forests may have different species assemblages, cover and phenology under climate change scenarios. These effects of climate change could have large and long-lasting impacts on forest communities in the central Appalachians.