What is an Ecological Classification System (ECS)?

ECS is a method used to identify, characterize, and map ecosystems. The Minnesota DNR system is based on the National Hierarchy of Ecological Units, developed by federal and , state resource management agencies and universities. It has been adopted by many federal, state, county, and private industrial natural resource management organizations in the United States.

 The aim of an Ecological Classification System (ECS) is to provide a format to convey basic information on the biological and physical characteristics of the landscape in a concise, integrated, standard and thorough manner. By mapping combinations of a landscape's various characteristics, ECS helps natural resource managers understand the landscape's capabilities for supporting a forest or wetland, providing wildlife habitat, producing a certain plant species, etc. This understanding can inform land use and resource management decisions. By providing a standard format, ECS allows information to be shared more easily among the various agencies, organizations, and individuals involved in natural resource management. 

Hierarchical Structure. ECS systematically divides the state into progressively smaller pieces generically called ecological units, because there represent different sized ecosystems. Minnesota has identified six different ECS levels of maps and information: Province, Section, Subsection, Land Type Association, Land Type, and Land Type Phases (the names given to the lower levels may vary among states). The number of ecological units or amount of detail is different at each level. At the Province level, Minnesota is divided into three units, while it will be divided into hundreds of units at the Land Type Phase level currently being developed. The upper levels (Province through Land Type Association) are created with existing information using geographic information systems. The lowest levels (Land Type and Land Type Phase) are being developed using data collected in the field on permanently located plots.

ECS is a dynamic system that can be refined with new information. Currently, the highest unit levels, Domain and Division, as well as Provinces and Sections have been established for the United States by the National Hierarchy. Many states, including Minnesota, have delineated units at the Subsection, Land Type Association and Land Type levels. The Minnesota DNR is currently developing a system to delineate Land Type Phase, or Habitat Type, level units across the state.  The ECS Levels describes how the level geographic areas are defined. 

The DNR also has information that describes the the ECS Provinces, Sections, and Subsections occuring in MN (http://www.dnr.state.mn.us/ebm/ecs/).

Biotic and Abiotic Characteristics. The essential elements (moisture, nutrients, energy and light) that help to describe ecosystems are very difficult to measure and map. At a fundamental level, it is the movement and use of these essential elements in a community of organisms that define an ecosystem. Instead, ECS uses a variety of biotic (living) and abiotic (nonliving) characteristics as substitutes to define and map ecosystems and their boundaries. These characteristics include the following: climate, glacial deposits, topographic relief, soils, plants, lake and stream patterns, and wetland patterns. They either directly influence or reflect the amounts of essential elements available. The relative importance placed on any one characteristic varies across the landscape and with the ECS level. For example, at the Province level, very general vegetation types (e.g., forest versus prairie) were used to determine unit boundaries. At the Land Type Phase level a small number of representative plant species are used to identify individual plant communities and unit boundaries such as Sugar Maple-Basswood Forest. This approach to delineation offers several advantages:

- Provides a method for mapping ecological units.

- Provides a format where the ecological units are relatively stable to change. (This is because ECS incorporates multiple characteristics to define and map ecosystems.)

Boundary lines vary in width. Boundaries between ecological units can vary in width for a couple reasons. The first is that the width of a boundary line depends on how distinct the contrast is between adjacent ecosystems and the characteristics used to define them. A line represents an area of transition with characteristics of both ecosystems. For example, at the Province level, climate is a dominant characteristic in defining ecosystems. However, changes in climate are very gradual. If you stood exactly on the line between the Prairie Parkland unit and the Eastern Broadleaf Forest unit, it would be difficult to determine the distinctions between the two sides of the line. However, if you went fifty miles either side of the Prairie Parkland-Eastern Broadleaf Forest line it would be much more obvious that they are two distinct ecosystems. 

The second reason unit boundaries vary in width is a matter of the difficulties of mapping the real world onto a piece of paper or a computer screen. The width of the boundary depends on the detail of the map. At the Province level, a pencil line on a map could be hundreds of feet wide on the ground. At the Land Type Phase level, the same pencil line may be only fifty feet wide.

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