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Harvard Forest REU Symposium Abstract 2010

  • Title: Deer, Moose, and Oak Regeneration in Central New England Forests
  • Author: Carlyn Perovich (Tulane University of Louisiana)
  • Abstract:

    In the past several decades New England forests have seen both an increase in ungulate populations and a general decline in oak regeneration. Although studies have linked high deer densities to poor oak regeneration at a landscape scale, it remains unclear whether ungulate browsing is an important factor controlling oaks at a regional scale. Our objectives in this study were to (1) investigate the hypothesis that an increase in ungulate browsing is reducing oak regeneration in central New England forests and (2) examine other environmental variables that may influence oak regeneration.

    We sampled 71 randomly located plots in central New England for oak seedling abundance and height, ungulate activity (browsing intensity and pellet counts), and other habitat characteristics including slope, aspect, overstory tree composition and basal area , shrub cover, and soils. We also examined broader land use characteristics such as forest fragmentation and calculated estimates of mean annual temperature for each plot. We analyzed oak seedling density in relation to several candidate models of predictor variables.

    Our results indicate that oak seedling density increases with both mean annual temperature and ungulate relative density. While a positive correlation between ungulate browsing and oak seedling density is unexpected, it could be explained by a number of factors. Ungulate browsing pressure is generally moderate in our study region, and at that level it may offer oak seedlings a competitive advantage by reducing competition from other tree seedlings and shrubs that are less able to resprout than oaks after being damaged. It is also possible that ungulates are attracted to areas with higher densities of oak seedlings because of the abundance of available browse. Further study focusing on the effects of different densities of ungulates on the recruitment of oak seedlings could offer greater illumination on relationships between ungulate browsing and oak regeneration.

  • Research Category: Conservation and Management