Rich Fen, Poor Bog
You might not expect to find an ecological wonder in the middle of Woodbury, but Tamarack Nature Preserve is not only the southernmost tamarack wetland in Minnesota, but also, it turns out, both a rich fen and a poor bog (more on that in a moment).
The Tamarack Nature Preserve (TNP) is a 169-acre city park in Woodbury with soft trails winding through woods and a unique boardwalk over the wetland. In 2019, the city upgraded the boardwalk to allow for better safety and “Adopt-A-Park” volunteers helped to create a new map and wayfinding signs, as well as numerous other tools to better connect visitors with the site.
Recently, Tamarack Nature Preserve was featured in Natural History Magazine in an article by Robert Mohlenbrock, professor emeritus of plant biology at Southern Illinois University. Upon touring the TNP, Mohlenbrock was surprised to find that the wetland has characteristics of both a fen and a bog. He writes, “A bog is acidic and receives its water from rain that usually falls into depressions. Bogs are nutrient-poor for plant growth. Fens, on the other hand, receive their water from the ground where water flows over calcareous material, such as limestone or dolomite. Fens are rich in nutrients, such as calcium and magnesium, and are alkaline. In the Tamarack Nature Preserve, both bog species and fen species intermingle with each other.”
Some of the plants characteristic of bogs that can be found in TNP include poison sumac, bog willow, winterberry, and tamarack trees. As the name implies, poison sumac contains the same oils present in poison ivy and oak, and can cause a severe allergic reaction if touched. Its leaves are quite different than those of the common staghorn sumac, and the plants have white berries instead of red.
Tamarack are a unique type of conifer, common in northern Minnesota, with needles that turn gold and drop in the fall like a deciduous tree. They thrive in acidic, nutrient-poor wetlands, peaty lakeshores, and along boggy edges of streams; can live to be more than 300 years old; and were documented to be the most common type of tree in Minnesota at the time of European settlement.
Tamarack are a unique type of conifer, common in northern Minnesota, with needles that turn gold and drop in the fall like a deciduous tree.
During his visit, Mohlenbrock also found numerous plants that are usually found only in nutrient-rich, alkaline fens. Some of these include Riddell’s goldenrod, bulblet-bearing water hemlock, white turtlehead, spotted Joe-pye weed, Kalm’s lobelia, and American black currant.
Unlike most wetlands in the area, the plants and trees at Tamarack Nature Preserve grow out of layers of peat that float on top of groundwater beneath, creating a quaking forest that is impossible to walk across (hence the need for a floating boardwalk). Peat forms when plants and trees in waterlogged areas die and only partially decompose, leaving layers of rich material that build up and compact over time.
Plants and trees at Tamarack Nature Preserve grow out of layers of peat that float on top of groundwater beneath, creating a quaking forest that is impossible to walk across.
Over the past two decades, the Ramsey-Washington Metro Watershed District has worked with the city and volunteers to implement numerous projects in and around Tamarack Nature Preserve to protect this unique habitat from invasive species and water pollution. Examples include a pond-like treatment system at the edge of the park that captures sediment and pollutants from road runoff, as well as raingardens and vegetated swales in neighborhoods surrounding the preserve.
Tamarack Nature Preserve is free and open to the public, year round, and is currently awash in a riot of fall colors. The park is located north of Valley Creek Rd., off of Tower Dr. Plan your visit.