The Nature Conservancy - Black Dog Scientific and Natural Area

Black Dog Scientific and Natural Area

Egret © Keith Lazelle

Black Dog Scientific and Natural Area is one of very few examples in the state of a calcareous fen — especially unusual because it lies within the greater Twin Cities metropolitan area. This fen, an upswelling of calcium-rich groundwater, harbors unique acquatic vegetation, such as valerian, and sterile sedge. The preserve also contains wet meadow and prairie components, and is part of the Minnesota Valley National Wildlife Refuge. Herons, egrets, and even songbirds inhabit Black Dog SNA during summer months. The preserve is managed cooperatively by Federal, State and Conservancy natural resources staff.

Location
Dakota County, Burnsville, south of Minneapolis/St. Paul

Size
130 acres

How to Prepare for Your Visit
Black Dog Preserve lies within the Minnesota Valley National Wildlife Refuge. For information on trails or about the refuge, call the Visitor Center at (952) 845-5900. As a Scientific and Natural Area, the preserve is protected by State laws forbidding disturbance of the fens. Signs are posted. For more information on visiting this and other Minnesota preserves, check out our Preserve Visitation Guidelines.

Directions
From Exit 4A off I-35W travel east 0.5 miles on the road that passes under I-35W to Cliff Road. The parking lot is 0.5 mile ahead on the north side of Cliff Road, and an MTC park and ride lot is nearby. A trail starting at the Refuge's information kiosk provides access to the preserve, winding 0.5 mile to the northeast and eventually joining a U.S. Fish and Wildlife Service trail. Nearest services are in Burnsville.

Plants
Black Dog Preserve includes wet prairie, wet meadow, mesic prairie, and the remnants of a calcareous fen community. The fen has a grass-based peat foundation, and is dominated by grasses and sedges. Although many rare species have disappeared from the preserve, valerian, and sterile sedge, both of which are listed as threatened by the state, have been observed recently. The prairie portions of the preserve are still in relatively good shape. The mesic prairie in the northeast part of the preserve is dominated by grasses such as big bluestem and prairie dropseed and includes a nice mix of forbs like yellow coneflower and blazing star. Wet prairie surrounds the mesic prairie.

Animals
North of the preserve lies Black Dog Lake, an important stop for migrating waterfowl. Some stay for the winter because a power plant keeps part of the lake open, making it one of the most popular bird-watching spots in the Twin Cities area. During the summer, egrets, herons, and double-crested cormorants inhabit the lake, while ring-necked pheasants and many songbirds, including willow flycatcher and orchard oriole can be found in the wet meadows and old fields. Bell's vireo is also an uncommon visitor.

Why the Conservancy Selected This Site
Until the mid 1800's, Dakota Indians lived in the area that now includes Black Dog Preserve. Led by their chief, Black Dog, this band of Dakotas lived by hunting and gathering. By 1855, settler Carl Wilcox obtained a patent on several parcels and planted some fields with hay. Records indicate that the fen area also was hayed until 1964. Landowners burned the fields every one or two years to stimulate production and controlled burning is still used to remove tree seedlings, shrubs, dried grass and exotic plants. Occasional wildfires also help improve the quality of wetland areas.

A railroad right-of-way was established in 1865 and freight trains continue to pass through. Areas of the preserve have been disturbed by rail traffic, ditch excavation, land-filling, and a power line. Urban development around the preserve further threatens the calcareous fen community. Calcareous fens are the result of glacial deposits that permit a constant upwelling of alkaline groundwater rich in calcium and magnesium bicarbonates. Many rare plants are largely restricted to fens, which cover just over 1,000 acres statewide. Surface water runoff from urban development around Black Dog has altered the flow and chemistry of the fen's water and dumped silt over much of the area. As a result, most fen species have disappeared.

What the Conservancy Has Done/Is Doing
The Nature Conservancy acquired the preserve in 1984, and it was designated a Scientific and Natural Area in 1987 by the State of Minnesota, along with adjacent land owned by the Department of Natural Resources. The MN-DNR has released leaf beetles at the site to help control the invasion of purple loosestrife. The history of this preserve is a lesson in the limits of conservation by land protection. Isolated preserves cannot maintain their integrity over the long term without some conservation efforts across the wider landscape.