Impact of deer on forests in Connecticut

Talk given by Dr Foster, Harvard Forest

Summary of talk given by David Foster, Director of Harvard Forest at Harvard University and Highstead’s Board Chairman, at Redding Land Trust’s annual meeting.
March 25 2007

David Foster talked about his research into the distribution of tree species across new England beginning 10,000 years ago (by taking core tube soil samples), covering the pre-settlement forest, the earliest surveyed land in colonial days, and up to the present time.
He discovered that pre-settlement Connecticut forest consisted mainly of hickories, chestnuts and oaks, while Cape Cod was mainly pines and New Hampshire and Vermont had a predominance of maples. Forest cover then steadily declined until 1850 after which it recovered again until very recently. Redding has an unusual amount of forest compared to other Connecticut towns.

A graph of wildlife dynamics from 1600 to today showed deer populations falling steadily from 1600 to 1800 then growing slowly until 1950 or so and then growing rapidly after that in an exponential fashion. Today there are many more deer in Connecticut than there were even in the pre-settlement days as we are providing them with the ideal habitat by developing into the woodlands and creating multiple “edge habitats”. The original dense forest was not an ideal habitat for deer and supported far fewer deer than today’s woodlands.

He then talked about Ed Faison’s vegetative study across plots on Nature Conservancy, Redding Land Trust and Highstead lands. Of note was  the fact that invasive Japanese barberry is concentrated in areas that were open land until fairly recently and are now becoming forested ie it likes to take hold in recently open pastures.

Forest ecologist Ed Faison will work this summer to broaden his studies of the role of invasive plants and deer browsing in southern New England forests. Invasive species research across Redding will be complemented by new observational and experimental research on deer impacts in the region's oak forests. The experiment will be modeled after Highstead's Woodland Demonstration in which 8-foot tall fencing excludes deer from some forest areas while adjoining areas remain open to deer. Outside these fenced areas is a clear browse line with elevation of the understory up to the height that deer can reach, while inside is 5 to 8 years of recovering wildflowers and saplings.

Spanning Redding and seven adjoining towns, the observational study will compare the abundance of tree seedlings and herbs in hunted versus unhunted forests on Highstead, Connecticut DEP, Aquarion Water Company, Nature Conservancy, private, and municipal properties. Ed's group will also establish permanent plots in properties where hunting was initiated in 2006 to measure forest changes as the deer population is reduced. 
When questioned by the audience Dr Foster agreed that hunting per se will not change the understory, only effective and significant reductions in deer numbers will do that. Their challenge will be to see if there actually are any changes in the deer density before analyzing their results.

Lastly, Ed plans to compare the growth rates of trees that have been exposed to very different deer densities by examining annual growth rings. 

For more information on these studies and to see maps of the locations of the deer exclosures and study sites, go to http://www.highsteadarboretum.org/general.htm