A comparison of created and natural wetlands in Pennsylvania, USA

  • Published source details Campbell D.A., Cole C.A. & Brooks R.P. (2002) A comparison of created and natural wetlands in Pennsylvania, USA. Wetlands Ecology and Management, 10, 41-49.


This study is summarised as evidence for the following.

Action Category

Restore/create freshwater marshes or swamps (specific action unclear)

Action Link
Marsh and Swamp Conservation
  1. Restore/create freshwater marshes or swamps (specific action unclear)

    A replicated, site comparison study in 1995 of 26 freshwater marshes in Pennsylvania, USA (Campbell et al. 2002) found that created marshes developed a wetland-characteristic plant community after 10 years, but had lower plant species richness and vegetation cover than reference (disturbed and pristine) marshes for up to 18 years. The overall plant community in >10-year-old created sites was characteristic of true wetlands, just like the community in reference wetlands. However, the overall plant community in <10-year-old created sites was characteristic of significantly drier conditions (data reported as a wetland indicator index). Regardless of age, created wetlands had a lower average plant species richness (3–6 species/79 m2) and vegetation cover (65–75%) than reference wetlands (10 species/79 m2; 95% cover). Methods: In June–August 1995, vegetation was surveyed across 26 freshwater marshes. Twelve marshes (0.2–5.3 ha) had been created in uplands approximately 2–18 years previously. The study does not report details of wetland creation methods. Fourteen reference marshes (0.1–2.1 ha), ranging from “disturbed” to “pristine”, were used for comparison. Plant species were recorded in 5-m radius circular plots, spaced 20 m apart across the whole of each wetland. Vegetation cover was recorded in a 0.25-m2 quadrat within each plot.

    (Summarised by: Nigel Taylor)

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust