Natural History: Minnesota's Landscape & Plant Communities



Native Plant Community: Lakeshore and northern hardwood forest

John Muir once said that any one thing is "hitched to everything in the universe." How then can we look at any one thing without becoming mired in a network of relationships? After years of developing specialized fields of science, how do professionals begin to come together to talk about ecological systems? And how do non-professionals approach an ecological understanding of a resource?

The Ecological Classification System (ECS) is one effort to integrate variables in understanding and describing what's going on in a given area.


The Ecological Classification System (ECS)

A nationwide mapping initiative, the Ecological Classification System (ECS), integrates data about climate, geology, hydrology, topography, soil, and vegetation--key ecological factors in determining the character of an area. Then it identifies, describes, and maps land to show its capabilities to support natural resources. This helps us better understand natural areas and their characteristics--plant communities, wildlife habitat, water quality, potential for restoration, and the changes that occur over time.

Provinces

The ECS in Minnesota has identified three major climatic zones, called provinces. Climate plays an important role in landscape development. Minnesota's climate is affected in the north by Arctic air and in the south by weather systems from the Gulf of Mexico. There is a division among the provinces, with coniferous forest in the colder northern climate, and prairie and deciduous forest most broadly distributed in the warmer, southern part of the state.

Native Plant Community: Prairie and floodplain forest

Provinces are large enough to contain localized areas not entirely characteristic of the province itself. For example, a bluff top in the Eastern Broadleaf Forest Province may produce a dry "goat" prairie rather than woodlands, due to its exposure, soils, and drainage. In turn, the Prairie Parkland Province contains not only prairies, but rivers lined by floodplain forests.

The ECS has further subdivided regional variations into landscape areas called sections and subsections. The relationships among provinces, landscapes, and individual SNAs are interesting to trace and significant to SNA protection decisions.

SNA site descriptions are arranged throughout this guide by the biomes within which they occur. Within each SNA are found several smaller levels of organization called plant communities.

Native Plant Communities

Plant and animal species flourish or perish, depending upon their environmental conditions. Local groupings of trees, shrubs, grasses, and forbs that interact with each other are called native plant communities, and are characterized by the kinds and quantities of species they contain.

Plant communities are subject to change. They form in response to features of the environment, such as climate, soil texture and nutrients, as well as catastrophic flooding and fire events. They can be fairly stable over time in the absence of change. A major change (such as flooding of a forested swamp by a beaver dam) can cause a new community to develop on a site. Also, over time, these groupings of plants can change the character of the environment to the point where other species can survive on the site and the community can transition from one to another.

Communities serve as the basis for evaluating SNA priorities. Since 1987, the Minnesota Biological Survey has identified, surveyed, and prioritized communities and rare species for research and conservation. Minnesota's Native Plant Community Classification, contains a description of 104 natural community classes and 223 community types. This classification serves as a standard for ecologists as they identify and assess communities. It is useful to anyone wishing to recognize and understand Minnesota's landscapes and Scientific and Natural Areas.

Native Plant Community: Conifer forest

Distribution and Diversity

Plant distribution varies with factors such as climate, soils, landforms, water drainage, and natural disturbances such as fire, flooding, wind, insects, and disease.

Before widespread settlement and land-clearing, fire in particular had a strong influence on the distribution patterns and character of many plant communities across Minnesota. For example, mature forests composed of fire-sensitive species developed where the spread of fire was prevented by rivers or lakes, whereas other parts of the landscape less protected from fire developed into diverse mosaics of fire-adapted forests, ranging in age from young post-fire stands to old forest stands, mixed with other kinds of plant communities adapted to fire. Fire, interacting with climate and landforms, was instrumental in determining where prairie developed in Minnesota, and during particularly dry times fire even influenced the character and distribution of certain kinds of wetland communities.

Human interaction by both American Indians and European settlers has also dramatically affected plant communities. This was most dramatic as settlers converted land to economic purposes. Wetlands have been drained, prairies plowed, forests logged, and habitat and food chain systems dramatically altered. In the process, we've introduced non-native species such as emerald ash borer, garlic mustard, purple loosestrife, buckthorn, and other invasive species. Consequently, many native plant communities have been reduced greatly in extent and many of the remaining examples support fewer of their characteristic native plant species.

The Value of Diversity and Intact Natural Ecosystems

Destruction and alteration of forests, native grasslands, wetlands, lakes, and rivers are rapidly reducing our biological diversity. Preserving biological diversity serves many purposes:

Native Plant Community: Southern hard forest and river systems

Disruption can take years to repair, and extensive destruction may eliminate the community. To eliminate a single natural community is to eliminate entire chapters of possibility for future development, at the same time eroding the natural system, or "scaffolding," that supports human life.

Minnesota has taken action to ensure preservation of representative natural communities through the SNA program. Learn to recognize SNA goals and related issues--to value, to support, and to enjoy. They are keys to our future.