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Harvard Forest REU Symposium Abstract 2009
- Title: The Effects of Ungulate Browsing on the Growth of Red Maple and Other Hardwoods
- Author: Sonia DeYoung (Harvard College (Harvard University))
- Abstract:
With the recolonization of moose and the rise of deer in southern New England, red maple and other hardwoods face the challenge of increased browsing pressure. We examined the effects of browsing on the height of red maple, birch, and oak seedlings and saplings, and on the abundance of red maple, in twenty-five recently harvested sites in the Quabbin and Ware River Watersheds in Massachusetts. Sites were chosen randomly, stratifying by age of harvest, forest type (oak-pine), harvest type, and proximity to major roads. We compared browsed status (browsed/unbrowsed) with stem height in three harvest age classes (2001-2002, 2004-2005, and 2007) for each of the three taxa. Then using the overall browsing intensity of each site along with other site characteristics as predictor variables, we analyzed the effects of browsing on red maple stem densities in five height classes. No significant relationship between height and browsed status appeared for any of the 2007 sites or for oaks in any age class. Browsed red maples of the 2001-2002 and 2004-2005 age classes were significantly taller than unbrowsed maples, and browsed birches taller than unbrowsed birches in the 2004-2005 class. This difference may be because browsing accessibility increases with height, or potentially because of compensatory growth under browsing pressure. Stem densities for red maple were not significantly decreased by browsing, but rather in lower height classes by percent fern cover. These results may suggest that red maple is relatively resilient under browsing pressure in regenerating oak-pine-maple stands of southern New England, and other factors instead may limit its growth and abundance. Given this resilience, growing deer and moose populations are unlikely to slow the rise of red maple that has occurred in eastern North America in the last century.
- Research Category: Physiological Ecology, Population Dynamics, and Species Interactions
