Anoka Ecosystems:
Lake Beach
Lake beaches, strictly defined, are sparsely vegetated communities which occur on sandy, silty, or mucky lakeshores. In Anoka County, these beaches occur along sandy lakes throughout the Anoka Sandplain. Within this ecosystem, there is an upper and lower beach zone in which the lower has emergent vegetation, such as annuals and perennials like St. John's-wort, and the upper having sparse vegetation, such as rice cut-grass and bulrushes, due to wave action and ice gouging.
Species in this community tend to be opportunistic and very resilient annuals and short-lived perennials, which are able to withstand erosion and distinct changes in water level. In addition, many are fast growing and produce seeds within a month of germination, which are then stored in the sediments until favorable conditions occur again. Common species include spotted touch-me-not, umbrella sedge, and least spike-rush.
Despite the commonality of this ecosystem historically, the lake beach communities have been gradually degraded and altered by human activities. Invasion of species such as purple loostrife and agricultural weeds degrade species diversity and composition, and erosion and dredging of the lake shore and lake bottom alter the natural ecosystem. Today, few lakes in Anoka County are colonized by native species. However, the few remaining good examples of this community within the county are along the shallow, sandy lakes on the Anoka sandplain.
Sources:
"Minnesota's Native Vegetation: A Key to Natural Communities"
Version 1.5 Minnesota Department of Natural Resources, Natural Heritage
Program, 1993.
Wovcha, D, Delaney, B, Nordquist, G. Minnesota's St. Croix River Valley and Anoka Sandplain: A Guide to Native Habitats Minneapolis: University of Minnesota, 1995.
