Natural History of Leddy Park

Lake Champlain beachfront at Leddy Park

The natural history story of Leddy Park can be dated back to the time when the land was covered in ice, long before the park (or even Lake Champlain) was formed. The rocks and landforms of Lake Champlain are home to some of the oldest fossil coral reef in the world (Lake Champlain Committee 2012). The precursors of the lake formed about 200 million years ago by the stretching of the lithosphere from continental extension of the earth’s plates. During this time, a large piece of bedrock fell between two faults and form a deep canyon known as the Graben Valley. During the Pleistocene, which occurred around 95,000 to 20,000 years ago, the Laurentide ice sheet covered the land as far as Long Island, NY and was about 1 mile high above the ground (Lake Champlain Committee).

As the glaciers grew thicker, they moved across the landscape through valleys and over mountains and dragged rocks and boulders beneath the ice sheet. The Laurentide ice sheet began to melt as the temperatures got warmer (beginning 20,000 years ago) and drained into the present-day Hudson River, creating Lake Vermont. The glacier receded north of the St. Lawrence Valley and the landmass it had covered was below sea level due to the heavy weight of the ice. Because it was below sea level, the saltwater from the ocean flowed in from the Atlantic to form the Champlain Sea. The land rebounded to the point that it was above sea level and the saltwater was thus replaced by freshwater from tributaries and created what we know today as Lake Champlain (Lake Champlain Committee). In a span of 10,000 years, the Champlain Sea left the Champlain Valley and was replaced by Lake Champlain. The principle surficial materials deposited in the valley from this event were the same glacial materials eroded and redeposited by small and large streams, waves, and currents in Lake Champlain, in addition smaller ponds (Wright). 

Leddy Park is located in the New North End of Burlington, and lies directly on the shore of Lake Champlain in Appletree Bay. Leddy Park is a 65-acre plot, including the beachfront area, and is used for recreation. Of this area, 65% of the land is woodland, 15% is mowed land, and 20% is for facilitative use (Burlington Parks Invasive Species Survey 2011). This park is near residential and commercial areas, so the surrounding extent is extremely developed. The park has lakefront property on Lake Champlain covering about 1,800ft of beach. 

Lake Champlain is the 6th largest body of freshwater in the United States, covering an area of 435 square miles and containing 6.8 trillion gallons of drinking water. The lake has five major segments:  the South Lake, long skinny and riverine; the Main Lake, the deepest and widest section; Mallets Bay, circumscribed by historical railroad and road causeways; the Inland Sea, which lies to the east of the Hero Islands; and Missisquoi Bay, a large and discrete bay rich with wildlife. Leddy Park is located along the Main Lake, very close to Mallets Bay. The shoreline community of Leddy Park includes natural sand beaches and dunes. These shoreline landforms can only be found in a few locations along Lake Champlain where rivers deposit their sediments or where currents wash eroded sands in the base of some bays. The currents of Appletree Bay are responsible for washing the eroded sands onto the beach at Leddy Park (Lake Champlain Committee).

Leddy Park forest stand

The park is home to a northern hardwood forest natural community. A natural community, as defined by Thompson and Sorenson (2000) in Wetland, Woodland, Wildland, is an interacting assemblage of organisms, their physical environment, and the natural processes that affect them. Northern hardwood forests are the most abundant forest in Vermont and have several variations. Leddy Park can be classified as a mesic red oak-northern hardwood community and has a gentle to steep slope topography with south-facing slopes. These communities are found in the warmer climates of Vermont, such as the Champlain Valley in Burlington along the coast of Lake Champlain (Thomson and Sorenson 2000). In Leddy Park, there is a large presence of red oak trees. In the map shown below, the two areas of the park with mainly red oak trees are defined. These two sides of Leddy Park are very densely populated with red oaks. Leddy Park is also home to many eastern white pine and red pine trees. The map labels the areas with these pine species dominant.

Productivity is high in mesic red oak-northern hardwood communities because of the constant inflow of nutrients from upslope (Thompson and Sorenson). The soil in Leddy Park is somewhere between well drained to excessively well drained and the parent materials are derived from ablation till. Ablation till is formed from a melting ice sheet, which is the Laurentide ice sheet of the Champlain Valley in the case for Leddy Park. Glaciers transported and deposited materials that ranged in size from the finest clay particles to blocks of rock hundreds of meters in size during melting. Till plains developed from materials deposited directly from the ice with the steady retreat of the glacier. When the glacial ice melted, the stream channel was deposited on the underlying surface and deltas formed at the end of these streams when they entered the lake (Christiansen 1979).

The mid-successional stages of the Leddy Park mesic red oak-northern hardwood community include sugar maple, red oak, basswood, beech, and hemlock, with the occasional butternut. Generally, the canopy is closed and the trees are tall and straight. The shrub and herb layers are usually sparse. Late successional trends of this community include beech, hemlock, and sugar maple as the dominators, with red oak in stands where a stable seed source is provided. In the case of Leddy Park, mature red oak is very common thus proof that the seed source is stable. Downslope movement is a very prominent ecological process. Fire is definitely known to play a role in mesic red oak-northern hardwood communities, in addition to human disturbance (Thompson and Sorenson). However, there have been no signs of fire in Leddy Park as of this year. Natural fire could potentially help the community in successional trends, but no such event has ever proved to be in existence in the area.

While walking through the woods of Leddy Park, it can be pointed out that there are many stonewalls and stonewall debris. These stonewalls give clues as to what the land was used for by the former inhabitants and visitors. It is difficult to date stonewalls but it is possible to tell from their construction what its purpose may have been. In Vermont, stonewalls were not present until fields were beginning to be plowed. The single thickness stonewalls were built by farmers with large stones for pastures. The walls that were double in thickness were built for extremely stony or cultivated fields. The stonewalls found around the property of Leddy Park appear to be single thickness, meaning the land was once used by farmers as a pasture for some type of animal, most likely sheep (Strimbeck and Bazilchuk 1999). The stonewalls in Leddy Park are found mainly in the area between the parking lot and baseball field, but some ruminants can be also found on the other side of the park as exemplified in the map below. The red dots represent the stonewall debris we found while crusing through the park.

Leddy Park Natural History Components

Key:
Red dots: stonewall debris
Red Oaks: dominant red oak stand
White and red pine: dominant pine stand

References 

Bazilchuk, Nancy, and Rick Strimbeck. Longstreet Highroad Guide to the Vermont Mountains.  Atlanta: Longstreet,1999. Print. <http://www.nasw.org/users/nbazilchuk/Articles/hgvtintro.htm>

Burlington Parks Invasive Species Survey. 2011. Lands Stewardship Program: Burlington Parks and Recreation. <http://www.uvm.edu/~conserve/lands_website/previous_projects/2011/BPR_invasives.pdf>

Christiansen, E.A. 1979. “The Wisconsinan Deglaciation of Southern Saskatchewan and Adjacent Areas, 
"Canadian Journal of Earth Sciences 116: 913–38; Sugden, D.E. and B.S. John. 1976. Glaciers and
Landscape. London: Edward Arnold. http://esask.uregina.ca/entry/glacial_deposition.html

"Natural History- In Brief." Lake Champlain Committee. N.p., 2012. Web. 28 Nov. 2012.               <http://www.lakechamplaincommittee.org/learn/natural-history-lake-champlain/>.

Thompson, Elizabeth Hathaway., and Eric R. Sorenson. Wetland, Woodland, Wildland: A Guide to the Natural Communities of Vermont. [Montpelier]: Vermont Dept. of Fish and Wildlife and the Nature Conservancy, 2000. Print.

Wright, Stephen F. "Glacial Geology of the Burlington and Colchester 7.5’ Quadrangles,   Northern Vermont." Vermont Agency of Natural Resources. N.p., n.d. Web. 28 Nov 2012. <http://www.anr.state.vt.us/dec/geo/pdfdocs/glacgeoburlwright.pdf>.

Lake Champlain photo credit: http://www.stad.com/index.php?city_id=5233789

Forest photo credit/map: Laura Wilson