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Much of the Northern Appalachian / Acadian region is soggy. Massive holocene glaciers left behind a legacy of deranged drainage patterns forming over a million acres of marshes, mudflats, seeps, swamps and spongy bogs. Wetlands constitute 2 percent of the ecoregion with over 29,000 discrete examples averaging 43 acres in size. They are unevenly distributed across subregions with the easternmost Acadian uplands and the Bras DOr lowlands having more wetlands than the rest of the subregions combined (Table 1 ). The largest wetland in the region is over 34,000 acres.

Ecologists recognize about 50 distinct wetland communities in the ecoregion based on species composition and structure. The dominant vegetation structure of the various wetland types tends to be correlated with the degree of permanent saturation and may be conveniently grouped into the broad categories listed below.

Swamp: a seasonally flooded wetland with more woody plants than a marsh and better drainage than a bog. (16 types).

Marsh: a frequently inundated wetland characterized by grassy or reedy (emergent herbaceous) vegetation adapted to saturated soils. (4 types)

Bog: a peat-accumulating wetland with no significant inflows or outflows, dominated by acid tolerant mosses (sphagnum) and characteristic shrubs and herbs. (12 types)

Fen: a peat-accumulating wetland that receives drainage from surrounding mineral soils and supports grassy marsh-like vegetation dominated by sedges. (10 types)

Wet meadow: a grassland with waterlogged soil near the surface but without standing water for most of the year. (1 types)

Other wetlands: seeps, flushes, seepage forest, floodplain, river-scour, pondshore and vernal pool systems  these wetland types are discussed in separate sections on floodplain and riparian ecosystems and small fluctuating wetlands..

Freshwater Wetland Portfolio Summary

The screening criteria used to locate and identify the wetlands most critical to maintaining biodiversity required that each qualifying example:

 Was large and contiguous: over 50 acres

 Was in good landscape settings (Land Cover Index < 20)

 Was in good condition based on ground surveys and expert opinion (corroboration by at least one source)

 Contained other confirmed biodiversity features (verification by element occurrences)

Many species tracked by the Natural heritage programs and Canadian CDCs were associated with freshwater wetlands (Table 4). The 50 acre size criterion was determined by an analysis of over a thousand survey records for species occurring in wetlands supplemented by a literature analysis of breeding requirements. Of 284 species recorded for these wetlands, one third were found only in wetland occurrences over 50 acres and two thirds had the majority of their occurrences in the larger wetlands (Tables 5 and 6).

Results

Our goal was to locate a minimum of 20 examples per 29 bedrock/elevation combination. This goal of 580 individual occurrences totals to 2 % of all wetlands in the ecoregion or an estimated 11% of all wetlands by area (using the mean size of qualifying wetlands). After examining the distribution of large wetlands (>50acres) we redistributed the goal of 580 across the bedrock/elevation classes in proportion with the number of possible occurrences (Table 7)

Our results identified 568 critical occurrences, 12 less than the number needed to meet our overall minimum goals. We were close to meeting the proportional goals for each bedrock/elevation setting with 17 of the target combinations meeting or surpassing the goal and 13 being below the goal (Table 7). Most of the deficits were in the common types and most of the surpluses were in the more unusual types  a distribution that may be acceptable given the conservation focus on some of the rarer examples.

When measured by area, the critical sites account for 24 percent of all wetlands, more than the expected estimate of 11 % because the critical sites where consistently higher than the average size. The critical occurrences identified total to 226,713 acres of unprotected wetlands (Figure 9).