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Ecoregions of Maine

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About the Ecoregions of Maine

Maine is the northeasternmost state in the United States. It can be divided into 19 different ecoregions. Although Maine's borders do not correspond well to ecoregion boundaries, the state as a whole is large and encompasses six ecoregions that are contained entirely within its borders.

Most broadly, Maine can be divided into two regions: the Northeastern Highlands encompasses the northwestern, more inland parts of the state. This region is higher-elevation, colder, and more dominated by conifers or boreal forest. The rest of the state is all part of the Mixed Wood Plains, a region that is lower-elevation and has a milder climate; in Maine this region is also ocean-moderated. This region can in turn be divided into two broad sections, the slightly cooler, rockier Acadian Plains and Hills, covering most of the state, and the milder Northeastern Coastal Zone, only found in the southernmost corner of the state.

The entire state has a humid continental climate with warm summers and cold winters. However, the severity of winters differs greatly, with more inland, more northerly, and higher-elevation regions having colder winters. Coastal regions have a more moderate climate year-round, with greater fog and higher humidity. Throughout the state, humidity and precipitation tends to be high year-round, but total precipitation is significantly higher both at high elevations, and in the coastal regions, especially towards the east. Total preciptitation is lower in the north, but this is largely a function of colder air not holding as much moisture, and these regions are not limited by moisture availability.

Geologically, Maine is diverse, and the diversity often extends into most localities, with most parts of the state having a variety of different bedrock types within short distances. The entire state was recently glaciated, but the erosion-resistant rocks left a landscape that was still quite rugged locally. Calcium content of rocks varies locally, and the rugged topography in many regions results in varying depths and particle sizes of glacial till and bedrock outcroppings throughout much of the state, especially in the hillier areas. In general, the state is more mountainous to the northwest, and slightly flatter to the southeast.

The southernmost part of the state, in the Northeastern Coastal Zone, is divided into the Gulf of Maine Coastal Lowland, directly along the coast, and the Gulf of Maine Coastal Plain, just inland from there. Both regions extend through New Hampshire and into Massachussets. The Coastal Lowland is the only part of Maine with a flat coastline and an abundance of large salt marshes and tidal wetlands, and it is the most populous and developed region of coast.

Moving along the coast, the Midcoast has a rockier coastline with numerous islands, bays, and peninsulas, and east from there, the Downeast Coast has an even steeper coastline with some taller cliffs and Mt. Desert Island. Inland (to the north) from the Midcoast, the Central Maine Embayment is a relatively flat region with fertile soils, and is both Maine's most important agricultural region, as wess as one of the regions highest in plant biodiversity. East of this, the Penobscot Lowlands are a small, low-lying area with fine-textured soils. Farther east, the Eastern Maine-Southern New Brunswick Plains are a large region that is sparsely populated and less utilized for agriculture. In the far northeast of the state, the Aroostook Lowlands are another important agricultural region, growing mostly potatoes.

Looking northwest from these regions, a series of "foothill" regions represent transitions between the milder, more coastal areas, and the more mountainous inland regions. In the southwest, the Sebago-Ossipee Hills and Plains are a region of plains, hills, and lakes. Northeast from this lies the relatively small Western Maine Foothills. Farther east and northeast there are the Central Foothills, and in the northernmost part of the state, the Aroostook Hills. Moving northeast, the climate in these regions gets progressively colder.

The coldest parts of the state include the higher-elevation White Mountains/Blue Mountains in the west of the state, and north of this, the Quebec/New England Boundary Mountains. In both of these mountain ranges, the highest elevations are separated into the Upper Montane/Alpine Zone. Northeast from these regions lies the Moosehead-Churchill Lakes, a flat, high-elevation region with abundant lakes. This region is bordered to the north by the St. John Uplands, and in the far northern corner of the state there are two small regions, the Upper St. John Wet Flats and the International Boundary Plateau.

References

1. Griffith, G.E., Omernik, J.M., Bryce, S.A., Royte, J., Hoar, W.D., Homer, J.W., Keirstead, D., Metzler, K.J., and Hellyer, G. "Ecoregions of New England (Poster)", U.S. Geological Survey (2009) Web.