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Harvard Forest REU Symposium Abstract 2012
- Title: Changing Vegetation Structure in Current and Former Plantations at Harvard Forest
- Author: Anne Cervas (Harvard College (Harvard University))
- Abstract:
While pine and spruce plantations were an important component of forestry in New England over the first half of the 20th century, plantation activity ceased in the 1950s due to extensive tree damage and mixed results in plantation growth. In 2007, about 55 hectares of plantations remained at Harvard Forest, in stands ranging from 0.4 to 15 hectares. Twenty-two 20 by 20 meter permanent plots were established in these plantations and the vegetation in these plots was surveyed in summer 2007. In 2008 and 2009, about half of the remaining plantation area was clear-cut to create a young forest cohort. This summer, I examined how vegetation structure and diversity have changed over the past five years, in order to determine the variation among the harvested sites, as well as examine the differences between harvested and forested sites. I compared vegetation measurements among sites to see the magnitude of changes in harvested versus control plots and to see if control sites have started the process of succession to native forest on their own accord. I expected that basal area would be higher in control sites, since they contain mature trees, but that all other measurements would be higher in the harvested plots, which should have more species diversity and tree regeneration as they grow back. I hypothesized that control plots may vary based on which planted tree species dominates, but I did not expect to see major differences between harvested plots on the same basis. My mentor and I revisited all twenty-two plots and recorded the species and diameter of all trees, stumps, snags, and coarse woody debris (CWD), the number and species of saplings, the presence of seedling species, and the composition and cover of understory vegetation. From my field measurements, I calculated and compared the differences in the overstory, in terms of basal area and stem density; regeneration, as measured by sapling density; the understory, in terms of understory species richness and community composition; and dead wood, as measured by the volume of CWD. Preliminary results suggest considerable variation among harvested and control sites, but little difference between the two types of sites as stem density, CWD, and species richness are not considerably higher in harvested sites. While basal area appears to be much higher in control sites than harvested sites, basal area is declining in control sites, which suggests that plantation stands may be ceding to native forest. Finally, neither control nor harvested sites seem to exhibit extensive variation on the basis of dominant planted tree species. My results have important implications for future research and forest management at the Harvard Forest, as extensive variation among harvested or control sites may limit application of research in sites across the Harvard Forest. In addition, evidence of the natural break up of plantations or variation across sites based on current or former plantation species can inform decisions about forest management.
- Research Category: Conservation and Management; Group Projects; Large Experiments and Permanent Plot Studies
