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Introduction
I. Massachusetts Ecoregions
As previosuly noted, ecoregions are based on combinations of factors including geology, geography, vegetation, soil types, land use, wildlife, scale of human development, hydrology, and climate (temperature and precipitation) such that no one parameter dominates the classification.
FIGURE 1: US EPA Level IV Ecoregions
Modified From: US EPA Ecoregion Models Web Site
The Ecoregion classification for the State (FIGURE 1 above), provides a sub-county identification of areas with similar characteristics. The state is divided into three Level III regions (dark lines), and 13 level IV regions as follows:
58 Northeastern Highlands - The Northeastern Highlands comprise a relatively sparsely populated region characterized by nutrient poor soils blanketed by northern hardwood and spruce fir forests. Land-surface form in the region grades from low mountains in the southwest and central portions to open high hills in the northeast. Many of the numerous glacial lakes in this region have been acidified by sulfur depositions originating in industrialized areas upwind from the ecoregion to the west.
58a Taconic Mountains - An area of high hills and low mountains that contain the highest point in the state, Mt. Greylock. Streams are high gradient and lakes and ponds are rare. Vegetation is generally northern hardwoods with some spruce-fir at higher elevations.
58b Western New England Marble Valleys/Berkshire Valley/Houstonic and Hoosic Valleys - This area is drained by the Hoosic and Housatonic Rivers. This area harbors farms, evergreen forests, transition and northern hardwood forests, and calcareous fens. The limestone in the area creates alkaline lakes and streams.
58c Berkshire Highlands/Southern Green Mountains: The Deerfield, upper Westfield, Hoosic, and Housatonic Rivers drain this area. Lakes and ponds are relatively abundant. This area has deep soils that support northern hardwoods and spruce-fir forests.
58d Lower Berkshire Hills - Similar to the Berkshire Highlands with its common northern hardwoods, but lacks spruce-fir and harbors transition hardwoods. Lakes and ponds are relatively abundant.
58e Berkshire Transition - Forests are transition hardwoods and northern hardwoods. This area drains to the Westfield and Connecticut River basins.
58f Vermont Piedmont - Forests are transition hardwoods and northern hardwoods. Hills are sometimes quite steep. Surface waters are highly alkaline. This area drains to the Deerfield and Connecticut River basins.
58g Worcester Plateau - This area includes the most hilly areas of the central upland with a few high monadnocks and mountains. Forests are transition hardwoods and some northern hardwoods. Forested wetlands are common. Surface waters are acidic. Many major rivers drain this area.
59 Northeastern Coastal Zone - Like the Northeastern Highlands, the Northeastern Coastal Zone contains relatively nutrient poor soils and concentrations of continental glacial lakes, some of which are sensitive to acidification; however, this ecoregion contains considerably less surface irregularity and much greater concentrations of human population. Although attempts were made to farm much of the Northeastern Coastal Zone after the region was settled by Europeans, land use now mainly consists of forests and residential development.
59a Connecticut River Valley - The borders of this region are easily defined by the bedrock geology. It has rich soils, a mild climate and low rolling topography. The valley floor is primarily cropland and built land. Central hardwoods and transition hardwood forests cover the ridges.
59b Lower Worcester Plateau - Comprises of open hills and transition hardwood and central hardwood forests. Most parts drain to the Chicopee and Quinebaug Rivers.
59c Southern New England Coastal Plains and Hills - Comprises plains with a few low hills. Forests are mainly central hardwoods with some transition hardwoods and some elm-ash-red maple and red and white pine. Many major rivers drain this area.
59d Boston Basin - Low hills and outlying hilly suburban towns mark this area’s rim. The basin itself has low rolling topography and numerous urban reservoirs, lakes, and ponds. The flat areas were once tilled, but are now almost exclusively urban and suburban developments.
59e Bristol Lowland/Narragansett Lowland - This region has flat gently rolling plains. Forests are mostly central hardwoods and some elm-ash-red maple and red and white pine. There are numerous wetlands, some cropland/pasture, and many cranberry bogs. Many rivers drain this area.
84 Atlantic Coastal Pine Barrens - This ecoregion is distinguished from the coastal ecoregion to the south by its coarser grained soils and Oak-pine potential natural vegetation, as compared to forests including hickory. Appalachian Oak forests and northern hardwoods were found in the coastal ecoregion to the north. The physiography of this ecoregion is not as flat as that of the Middle Atlantic Coastal Plain, but it is not as irregular as that of the Northeastern Coastal Zone.
84a Cape Cod and Islands - This region was formed by three advances and retreats of the Wisconsin Ice Sheet. The resulting terminal moraines. outwash plains, and coastal deposits characterize the area with their sandy beaches, grassy dunes, bays, marshes, and scrubby oak-pine forests. There are numerous kettle hole ponds, swamps, and bogs. Much of the surface water is highly acidic.
The Level III Ecoregions closely approximate the topography of the state. FIGURE 2 (below) is a topographic map of the state. (FIGURE 1 has been repeated below FIGURE 2 to ease comparisons.)
The Northeastern Highlands (58) correspond (roughly) to elevations of 1,000 feet AMSL or greater. The Northeastern Coastal Zone (59) includes elevations up to 1,000 feet AMSL and covers the Connecticut Valley Lowlands, the southern half of the Eastern New England Upland where the elevations are somewhat lower than those of the northern half, and the Coastal Lowlands eastward to the approximate boundary of Plymouth County. The Atlantic Coastal Pine Barrens (84) includes Cape Cod and the islands of Martha’s Vineyard and Nantucket.
FIGURE 2: Massachusetts Topography
From: USGS
Level IV Ecoregions do offer a better correlation to topography in the western part of the state, (e.g., 58b and 59b), but show no apparent tie to elevations in the eastern part of the state (59c, 59d, 59e). This is an example of different factors used in modeling ecoregions showing dominance. The influence of elevation dominates in one region while coastal influences dominates in another.
FIGURE 1: US EPA Level IV Ecoregions
Modified From: US EPA Ecoregion Models Web Site
Massachusetts uses ecoregions to make environmental management of nonpoint-source pollution (NSP) easier (refer to Day 2 for more information), as well as for tracking other geospatial issues. Ecoregions also serve as a framework for lake assessment & classification (rather than the previous eutrophication-based system). Boundaries between ecoregions, or ecotones, are to some extent captured by the ecoregion system, however these transition areas can be so local that only very detialed mapping would be able to represent them.
Ecoregions give some insights into the dynamics of an area's condition that includes the type and level of disturbances and stresses present.
II. Weather, Climate, & Invasive Species
Climate delivers temperature and precitpitation to a given place at a given time (Dr. Charles Wax, Mississippi State Climatologist). As insolation (energy received from the Sun) and mositure changes from day to day and season to season in a given location, the number and variety of local animal and plant populations also change, as do the local soils, drainage patterns, etc.
Change the climate (temperatures / precipitation patterns) and a given ecoregion may increase or decrease in size, and the associated change in environmental stress experienced by the indigenous flora and fauna may allow for non-native species to invade leading to further changes. Climate change models predict an average global increase of 2-5°C by the end of this century. The current average global increase of 1° is just that, an average. Higher latitudes have seen localized increases of 5°-7°F, as compared to 1°, resulting in the thawing of permafrost. Regional soil warming will affect the soil processes of decomposition that could lead to broader changes to the ecoregion, release more CO2 that could change atmospheric chemistry, and affect global climate.
Can you change the climate by changing an ecoregion? Removing forests changes albedo (the reflectivity of a surface), can increase the temperature as more solar energy is absorbed, causes migration (or death) of the fauna that once lived there, increases precipitation runoff, reduces precipitation infiltration into the soil, and so on. Non-native invasive animal or plant species can directly affect local climate by altering characteristics of the ecoregion they invade. Shifts from native to non-native plants may have a similar outcome on local climate as when a forested area is converted into a field as described above.
Non-native invasive species reduce the amount of light, water, and food available to native species because they often lack natural predators or other local stresssors to keep them in check. Native animal and plant species are not competative with the non-native species and, as a result of this unequal competition, are often displace or die-out.
With a change in flora and fauna come changes to the local hydrologic cycle, soil chemistry, and the ability for soil to hold mositure or to be easily eroded that is not evident at first. Sometimes the new species may not be a suitable food source as the native species once were (i.e., caulerpa taxifolia - see NOVA's Deep Sea Invasion). Only after some period of time does the damage become apparent. The U.S. Fish and Wildlife Service has estimated that roughly ½ of the listed endangered and threatened species have seen further decline resulting from the stress of non-native invasive plants and animals.
Some of Massachusetts' better known non-native species include Purple Loosestrife, Eurasian Milfoil, and Eruopean Naiad. Native species in decline include the Purple Milkweed and Swamp Cotton Wood.
Severe weather can also bring changes. Coastal areas can be inundated by storm surge and coastal landforms can be altered or destroyed (see Day 6 background for more information). As the shoreline changes, areas once protected by a spit or bar may now be exposed to a higher energy environment leadng to a change in vegetative cover. Farther inland, hurricanes can create extensive forest damage with effects lasting for centuries.
Summary
FIGURE 3: Massachusetts Topography
From: USGS
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The background information presented here only briefly introduces the complexities of the subject. As noted in the introduction, many aspects of geology, climate, and life interact and result in the varied ecological regions across the state. In introducing ecoregions, we necesarily touched on climate and weather, but also on native and non-native species of flora and fauna, and how changes to one part of the system can lead to changes in other parts.
The site where we will explore this topic further (FIGURE 3 (left) is located very near to the boundary between two Level III ecoregions - 58 Northeastern Highlands and 59 Northeastern Coastal Zone. Various long-term research projects are currently underway that includes the topics outlined above.
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What Next?
The information presented above is meant to provide a context with which to understand the weather and climate of the region. During the field trip, additional information detailing data collection and interpretation will be presented.
Continue on to the
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