Flatiron Lake Bog is a rare classic tamarack-ringed bog. It is an acid, kettle-hole bog that displays the classic ringed zonation of bog plant communities. Furthest out are the upland kame ridges surrounding Flatiron Lake that are covered by mature oak-maple forests. The forest zone grades into the next zone of a tall shrub community dominated by highbush blueberry. The tall shrub zone then grades into a tamarack woods, then a shrub zone and floating sphagnum mat and finally an open pool in the center. The bog developed in a kettle hole that formed in the Kent end moraine when the Wisconsinan ice sheet retreated approximately 12,000 years ago, making the bog among the oldest kettle hole bogs in the country. The bog bears a striking resemblance to Canadian bogs some 300 miles further north.
The ecological significance of the bog was not recognized until 1980 when Dr. Barbara Andreas went there to investigate an area where tamaracks were reported to grow. The Nature Conservancy purchased a 77-acre tract near the bog in 1985. Additional acquisitions have increased the size of the preserve to 97 acres.
A few of the plants that are found there include: Tamarack, white beak-rush, pitcher-plant, two-scaped bladderwort, lesser bladderwort, Carolina yellow-eyed-grass, Howe’s sedge, white-fringed orchid, large & small cranberry, wild calla, leather-leaf and round-leaved sundew. Community types include tamarack-hardwood bog, tall shrub bog, and sphagnum bog.
Why We Selected This Site
Flatiron Lake Bog may be the best example of this community in the state. Flatiron maintains an insulated microclimate where a host of northern plants can survive far south of their normal range. More than 15 rare species are found in the bog. Surrounding the kettle-hole bog depression are well-drained kame ridges and hills that support oak-maple forest. These forests are primarily secondary. However, one stand of trees located on a peninsula that rises slightly above the kettle-hole supports individual trees of impressive height and diameter.
The primary threats to Flatiron Lake Bog are the negative effects of human disturbance, invasion by weeds, and, potentially, woody succession. The surrounding forest community is most threatened by the invasion of non-native plants which can displace the native shrubs and herbs in the understory. Gravel mining to the south has the potential to negatively impact water quantity in the bog. Farming to the west could degrade water quality through soil erosion and pesticide and nutrient runoff. Trespassing, from both all-terrain vehicles and hikers, could destroy both upland and bog communities or populations of rare plants.
What We Have Done/Are Doing
Limited management and monitoring activities are conducted to assure the long-term viability of the bog and its plant communities. Focused control of weed species in the upland woods is a priority. Acquisition of additional land as opportunities permit will further protect the site.