Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources; they are designed to serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components. Ecoregions are directly applicable to the immediate needs of state agencies, including the selection of regional stream reference sites, the development of biological criteria and water quality standards, and the establishment of management goals for nonpoint-source pollution. They are also relevant to integrated ecosystem management, an ultimate goal of most federal and state resource management agencies.

The approach used to compile this ecoregion map is based on the premise that ecological regions can be identified through the analysis of the patterns of biotic and abiotic phenomena that reflect differences in ecosystem quality and integrity (Wiken 1986; Omernik 1987, 1995). These phenomena include geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another regardless of the hierarchical level. This map of level III and IV ecoregions of Massachusetts, Rhode Island, and Connecticut was compiled at a scale of 1:250,000; it depicts revisions and subdivisions of earlier level III ecoregions that were originally compiled at a smaller scale (Omernik 1987). Compilation of this map was part of a collaborative project between the U.S. EPA Environmental Research Laboratory-Corvallis and the Massachusetts Department of Environmental Protection, Division of Water Pollution Control during 1992-1994. Similar collaborative projects with Connecticut and Rhode Island have not yet occurred, and boundaries in those states should be considered as draft. Explanations of the methods used to define the U.S. EPA's ecoregions are given in Omernik (1995), Griffith and others (1994), and Gallant and others (1989).

Literature Cited:

Gallant, A.L., Whittier, T.R., Larsen, D.P., Omernik, J.M., and Hughes, R.M., 1989, Regionalization as a tool for managing environmental resources: Corvallis, Oregon, U.S. Environmental Protection Agency EPA/600/3-89/060, 152 p.

Griffith, G.E., Omernik, J.M., Pierson, S.M., and Kiilsgaard, C.W., 1994, Massachusetts ecological regions project: Corvallis, Oregon, U.S. Environmental Protection Agency EPA/600/A-94/111, 58p.

Griffith, G.E., Omernik, J.M., Wilton, T.F., and Pierson, S.M., 1994, Ecoregions and subregions of Iowa - a framework for water quality assessment and management: The Journal of the Iowa Academy of Science, v. 101, no. 1, p. 5-13.

Omernik, J.M., 1987, Ecoregions of the conterminous United States (map supplement): Annals of the Association of American Geographers, v. 77, no. 1, p. 118-125, scale 1:7,500,000.

Omernik, J.M., 1995, Ecoregions-a spatial framework for environmental management, in Davis, W.S. and Simon, T.P., eds., Biological assessment and criteria-tools for water resource planning and decision making: Boca Raton, Florida, Lewis Publishers, p. 49-62.

Wiken, E., 1986, Terrestrial ecozones of Canada: Ottawa, Environment Canada, Ecological Land Classification Series no. 19, 26 p.

PRINCIPAL AUTHORS: Glenn E. Griffith (USEPA), James M. Omernik (USEPA), and Suzanne M. Pierson (ManTech Environmental Technology, Inc.).