Comparison of created and natural freshwater emergent wetlands in Connecticut (USA)

  • Published source details Confer S.R. & Niering W.A. (1992) Comparison of created and natural freshwater emergent wetlands in Connecticut (USA). Wetlands Ecology and Management, 2, 143-156.


This study is summarised as evidence for the following.

Action Category

Reprofile/relandscape: freshwater marshes

Action Link
Marsh and Swamp Conservation
  1. Reprofile/relandscape: freshwater marshes

    A replicated, site comparison study in 1988 of ten freshwater marshes in Connecticut, USA (Confer & Niering 1992) found that excavated marshes contained more open water and less vegetation cover than natural marshes, but similar richness of wetland plant species. After 4–5 years, the area of open water was greater in excavated marshes (5–90%) than in natural marshes (0–40%). Within vegetated areas, excavated marshes had only 71% vegetation cover on average (vs natural: 97%). Cover and frequency of individual species showed mixed results (see original paper for data; statistical significance not assessed). For example, broadleaf cattail Typha latifolia cover was lower in excavated than natural marshes in three of five comparisons, but higher in excavated than natural marshes in the other two comparisons. In contrast, tussock sedge Carex stricta always had similar or lower cover in excavated marshes compared to natural marshes. Finally, there was a statistically similar number of wetland plant species, on average, in excavated marshes (33 species/marsh) and natural marshes (30 species/marsh). Methods: In summer 1988, vegetation was surveyed in five created marshes (excavated in 1983–1984) and five nearby natural marshes. All marshes were <1 ha. Although paired geographically, created and natural marshes contained different soils and water levels. The total open water area was visually estimated. Plant species and their cover were recorded in at least forty 1-m2 quadrats/marsh, placed in vegetated areas. Some of the marshes in this study were also studied in (4).

    (Summarised by: Nigel Taylor)

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