Study

Avian communities of created and natural wetlands: bottomland forests in Virginia

  • Published source details Snell-Rood E.C. & Cristol D.A. (2003) Avian communities of created and natural wetlands: bottomland forests in Virginia. The Condor, 105, 303-315.

Actions

This study is summarised as evidence for the following.

Action Category

Reprofile/relandscape: freshwater swamps

Action Link
Marsh and Swamp Conservation

Restore or create inland wetlands

Action Link
Bird Conservation

Directly plant trees/shrubs: freshwater wetlands

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

    A replicated, site comparison study in 2000 of 11 freshwater swamps in Virginia, USA (Snell-Rood & Cristol 2003) found that created swamps – reprofiled then planted with trees/shrubs – had a similar proportion of habitat-characteristic vegetation and similar horizontal vegetation cover to similar-aged swamps recovering naturally from logging, but contained shorter woody vegetation with a lower basal area and density. After 7–11 years, created and naturally recovering swamps contained statistically similar proportions of tree species characteristic of four soil moisture classes (from “highly saturated” to “partially saturated”), had statistically similar vegetation cover (both ground and canopy) and contained herbs of statistically similar height (data not reported). However, woody vegetation in created swamps was shorter (created: 2.0 m; natural: 4.4 m) and had a lower basal area (created: 59 cm2/100 m2; natural: 519 cm2/100 m2). Finally, created swamps had lower horizontal vegetation cover, both 1 m and 2 m above the ground (created: 26–45%; natural: 83–92%). Methods: In summer 2000, vegetation was surveyed in 11 swamps of similar age, water level and surrounding land use. Six swamps had been created by reprofiling upland sites to increase soil moisture, then planting a mix of wetland trees/shrubs (and in one case, adding wetland soil). The study does not distinguish between the effects of these interventions on non-planted vegetation. Five swamps were recovering naturally after clearcut logging.

    (Summarised by: Nigel Taylor)

  2. Restore or create inland wetlands

    A replicated, controlled study from May-July in 2000 in Virginia, USA (Snell-Rood & Cristol 2003), found that bird species richness and diversity in artificially created wetlands were significantly lower than in natural wetlands (average of 11 species/site for six artificial wetlands vs. 17 for five natural wetlands). Although total bird abundance, and the abundance of wading birds, waterfowl, raptors, aerial feeders or woodpeckers were similar, natural wetlands had significantly higher songbird abundance. In addition, created wetlands exhibited bird communities with significantly lower conservation value (based trophic level and migratory status) but similar average habitat specificity and wetland dependency. All wetlands had similar surrounding habitats and were of similar ages (time since planting for created and since logging for natural wetlands), and sizes (5-15 ha).

     

  3. Directly plant trees/shrubs: freshwater wetlands

    A replicated, site comparison study in 2000 of 11 freshwater swamps in Virginia, USA (Snell-Rood & Cristol 2003) found that created swamps – planted with trees/shrubs after reprofiling – had a similar proportion of habitat-characteristic vegetation and similar horizontal vegetation cover to similar-aged swamps recovering naturally from logging, but contained shorter woody vegetation with a lower basal area and density. After 7–11 years, created and naturally recovering swamps contained statistically similar proportions of tree species characteristic of four soil moisture classes (from “highly saturated” to “partially saturated”), had statistically similar vegetation cover (both ground and canopy) and contained herbs of statistically similar height (data not reported). However, woody vegetation in created swamps was shorter (created: 2.0 m; natural: 4.4 m) and had a lower basal area (created: 59 cm2/100 m2; natural: 519 cm2/100 m2). Finally, created swamps had lower horizontal vegetation cover, both 1 m and 2 m above the ground (created: 26–45%; natural: 83–92%). Methods: In summer 2000, vegetation was surveyed in 11 swamps of similar age, water level and surrounding land use. Six swamps had been created by planting a mix of wetland trees/shrubs after reprofiling upland sites to increase soil moisture (and in one case, adding wetland soil). The study does not distinguish between the effects of these interventions on non-planted vegetation. Five swamps were recovering naturally after clearcut logging.

    (Summarised by: Nigel Taylor)

Output references
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