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(Article from Friends of Charleston Lake Park)

Charleston Lake has the interesting distinction of being cradled in two distinct bedrock types: granite and sandstone. This feature has not only determined the physical shape and characteristics of the lake and its ecology, but has shaped the course of its history and land use as well. For the most part, the southwest end of the watershed is on igneous bedrock and the northeast portion is on sedimentary rock. As a watershed, the region is nearly equally split between the two bedrock types.

Charleston Lake, towards the southwest, sprawls through the valleys of the ancient metamorphic bedrock of the youngest plate of the Precambrian Canadian Shield, known as the Grenville Province. This granite and gneiss and schist bedrock dates to nearly a billion years ago, when shifting plates of the earth’s crust collided and pushed an enormous range of mountains into existence. Over hundreds of millions of years, the softer rock of the mountain peaks weathered away, leaving only the “roots” of the mountains; the durable rock cradling the lake today. The northeast-southwest trend of the ridges and valleys belies the orientation of the long-eroded mountains. The shape of the lake is molded by the pattern of the slopes and valleys of the old mountain roots. While glaciers gouged and rounded and deepened and broadened the old valleys over millennia, the topography today is not unlike that of hundreds of millions of years ago.

The softer, layered bedrock found in most of the northeastern watershed are sedimentary forms, or those that formed originally as weathered particles in shallow seas which flooded vast regions long ago. These sandstones consist mostly of weathered particles carried to the seas, but as well some fossilized bodies of the very primitive life-forms of the times.

Dating to something approaching 500 million years ago, this softer rock has not endured so resolutely as the harder granites, and the vagaries of climate and numerous glaciations have worn much away. Even so, there are patches of sandstone around and in Charleston Lake.

The characteristics and chemistry of the two bedrock types are quite different, and so their presence together significantly lends to the diversity of ecology, and history too. Plants and wildlife are adapted to live best on one type or the other, but when the two bedrock types border each other, there is additional diversity along the border. Land use patterns as we recognize them are quite different on the contrasting bedrocks. On the shield type rock, roads, like waterways, meander in valleys among the hills. Settlements arose strategically at falls of water and transportation routes on the shield, but were less confined on the flatter lands of the sedimentary plains. Shield farms were patterned on that of clay basins in the granite outcrops, where on the flat plains, farm properties could be sectioned and fenced into neat rectangles. 

In this watershed, the much of the Charleston Lake area itself is in the granite bedrock, and substantial development in large measure passed it by. Upstream in the watershed, on the more level sedimentary plains, considerably more land was cleared in forestry and in great measure remained cleared for agriculture and community.

The Ecological Setting
In broad terms, the forest region is part of the Great Lakes – St. Lawrence Lowlands Forest Region. A closer view, though, shows an ecology that is extremely complex. Almost all of the forest regions of eastern North America intersect in the Biosphere Reserve, at a unique crossroads of landforms. Here, the ancient Canadian Shield reaches deeply south to the Adirondack Mountains in an hourglass-shaped formation called the Frontenac Arch, flanked by the far younger plains of layered sedimentary rocks. Slashing across the Arch is the St. Lawrence River, connecting the Great Lakes to the Atlantic coast. The Arch and river landforms became corridors for the short and long-term migration of plants and animals.

Plants and animals of the boreal northland, the Atlantic coast, the continental heartland, the Appalachian mountains and the Carolinian south migrate those landform corridors, and interact and intermingle here. As a result, the diversity of our biology, our ecology in our Park, is astounding. Not only are the simple numbers of species large here, in the top three in Canada, but the diversity in terms of the geographical ranges of these species is extraordinary.

A climate modified by the Great Lakes, a broad range of soil and rock types and chemistries, a diverse topography of hills, cliffs and valleys, and a range of land uses create a hugely complex physical landscape. This allows a tremendous number of habitats and niches to exist here, and in turn there are opportunities and the conditions for the multitude of plants and animals that have populated the area from so many other parts of eastern North America.

The highlight of this biodiversity is that a goodly number of the plants and animals here are at or near their natural range limits. For example, almost all of the three-needled Pitch Pine, common on the New Jersey Pine Barrens, is found only in this region of Canada. The same is said of our largest snake, the eastern rat snake (formerly called the black rat snake).

Red spruce and wire birch are typical trees in Atlantic coast forests, and reach inland just this far west. Balsam fir, sweet gale and barren grounds strawberry are boreal forest plants that have southern range extensions into our area. There are complexity here.

It is not surprising that because so many species are intermixed and near the ends of their extended ranges, the Park hosts a high proportion of species that are designated rare, threatened and endangered. While we hear every day about dire situations for numerous plants and animals around the globe, we need look no further than our own forests and wetlands for species that are equally precarious. At present, there are 32 Species at Risk in the region; a number that while one of the highest in Canada shows the richness of the landscape. These sometimes rely on very precise conditions for their habitat, and as habitats are compromised, species may be lost from that location, and from the region itself. Our stewardship of habitats, however small, can make a considerable difference in the continued diversity of this world recognized ecology.

Our forests began developing the character we see today about 3,000 years ago. Prior to that time, the forests were evolving through successions of forest types as the continent adjusted to the climate changes following the last ice age.

Sugar maple, beech, paper birch, hemlock, red oak and white pine are most numerous, with basswood, red maple, white ash, shagbark hickory, white oak, red pine and ironwood being quite abundant as well. West-facing points of land and exposed granite ridge tops host species that tolerate the dry and windy conditions. Ground covers of blueberries, sedges and tufts of moss grow on the thin, coarse soil, with pitch pine, June berry and red oak overhead.

Broader valleys between the ridges often cradle deeper pockets of clay, left from the old post-glacial lake bottoms. Here, deep-rooted trees such as sugar maple, American beech, Canadian yew and shagbark hickory cast deep shade over carpets of trilliums, dogtooth violets, gooseberry and myriads of other shrubs and wildflowers. Steeper northfacing slopes are cool and damp, favouring stands of hemlock, striped maple, elderberry and polypody ferns. Broad ridges with shallower soil, and often with rock outcrops, host savannahs of white oak, white pine, ironwood, coarse sedges and grasses and many fern species. There are several other community types as well.

Alvars—characterized by shallow soils on sedimentary bedrock, with extremes of temperature and wet and dry conditions—are a globally rare habitat found only around the Baltic Sea and Great Lakes, but are nearly 8% of the watershed’s habitat types and are found on the lake’s islands and shorelines. The waterways, all with their own complex variations of depth, bottom type, currents and slopelend to the vast array of wetland and aquatic habitats. Therefore, the lake too has surprising diversity. The fish community, for example, has a variety of coldwater, coolwater and warmwater fish species.
At the time this region was first settled by immigrants, the array of habitats was very similar to those of today. 

The size of trees in those ancient forests, though, were often immense. When the land was cleared, new elements of habitat, such as fields and then old, abandoned fields, made opportunities to new species of both plants and animals. At the same time, though, habitat for some species was substantially reduced. Animal life was perhaps most affected. Timber wolves, moose, woodland elk, eastern cougar, black bear, lynx and martin were among those that could not survive the more limited and fragmented habitats. On the other hand, eastern cottontail rabbits and coyotes expanded their ranges to the region, and whitetail deer and raccoons thrived. Interestingly, as some of the forests age and abandoned fields reforest themselves, there are again occasional sightings of some of the former wilderness residents. 

There is much to be learned about animal species here, as some of the smaller animals, including reptiles and amphibians, have not been surveyed or studied sufficiently to understand their presence and populations, as well, there are landscape connections and potential for reconnections that may actually see wildlife become more successful in living here. This is one reason that the Friends have invested their funds and sought out funding to study species at the Park. In some respects, with this great diversity, we do not know what we do not know.

Flora & Fauna 
Charleston Lake Provincial Park contains a rich diversity of plant and animal species. This high diversity is due in large part to the Park’s mix of a northern geological landscape, and its southern location and warmer climate. The result is an intriguing blend of both northern species, such as Black Spruce and Pitcher Plant, and southern species, like Pitch Pine and Shagbark Hickory. The park is sanctuary to 9 species at risk, including the Black Ratsnake, Red-shouldered Hawk and the Southern Flying Squirrel. Thirty-five species of mammals can be found in the park, such as Beaver, White-tailed Deer, Fisher and Mink. Charleston Lake is known for its high diversity of reptiles and amphibians, with Northern Map Turtles and Eastern Ribbonsnakes being commonly seen by park visitors. Intriguing birds such as Cerulean and Golden-winged Warblers and Yellow-billed and Black-billed Cuckoos are sure to catch the attention of many birdwatchers.

The Heart of the UNESCO Frontenac Arch Biosphere
One of 15 Biosphere Reserves located in Canada, the Frontenac Arch Biosphere was designated by UNESCO's Man and the Biosphere Program in November 2002.  As of May 2009, there are 553 World Biosphere Reserves located in 107 countries.

The Frontenac Arch Biosphere Reserve extends roughly 2700 square kilometers in the south eastern Ontario and includes both Charleston Lake and Frontenac Provincial Parks.  Visit  its website for more information.

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