Study

Ecological outcomes and evaluation of success in passively restored Southeastern depressional wetlands

  • Published source details De Steven D., Sharitz R.R. & Barton C.D. (2010) Ecological outcomes and evaluation of success in passively restored Southeastern depressional wetlands. Wetlands, 30, 1129-1140.

Actions

This study is summarised as evidence for the following.

Action Category

Restore/create freshwater marshes or swamps (multiple actions)

Action Link
Marsh and Swamp Conservation

Directly plant trees/shrubs: freshwater wetlands

Action Link
Marsh and Swamp Conservation
  1. Restore/create freshwater marshes or swamps (multiple actions)

    A replicated, before-and-after, site comparison study in 2000–2005 of 16 ephemeral freshwater wetland restoration sites in South Carolina, USA (De Steven et al. 2010) reported that multiple interventions changed the vegetation type, cover and species richness. Results summarized for this study are not based on assessments of statistical significance. Before intervention, the sites were dominated by facultative wetland trees (data not reported). They contained 23 plant species on average (including 8 wetland-characteristic) and had 141% overall vegetation cover (woody: 130%; herbaceous: 10%; wetland-characteristic: 48%). Reference wetlands contained 10–33 species. After one year, restored wetlands were dominated by facultative and wetland-characteristic herbs. They contained 43 plant species (including 22 wetland-characteristic) and had 77% vegetation cover (woody: 18%; herbaceous: 59%; wetland-characteristic: 39%). After five years, restored wetlands contained a mixture of herbs and young woody plants. They contained 35 plant species (including 21 wetland-characteristic) and had 102% vegetation cover (woody: 40%; herbaceous: 64%; wetland-characteristic: 63%). At this point, the overall plant community in restored wetlands was 37–41% similar to 29 reference local marsh and swamp communities (vs 36–41% similarity between natural marsh or swamp communities from different sites). For data on the abundance of individual plant species, see original paper. Methods: In 2000–2002, sixteen degraded wetlands (≤2 ha; drained and overgrown) were subjected to multiple restoration interventions: plugging drainage ditches, cutting and removing existing trees, and applying herbicide to resprouting stumps. Eight of the wetlands were also sparsely planted with seedlings of wetland-characteristic trees. Vegetation was sampled in August before restoration (2000) and for five years after (2001–2005). Some of the restored wetlands in this study were also used in (10) and (11).

    (Summarised by: Nigel Taylor)

  2. Directly plant trees/shrubs: freshwater wetlands

    A replicated, randomized, controlled, before-and-after study in 2000–2005 in 16 ephemeral freshwater wetlands undergoing restoration in South Carolina, USA (De Steven et al. 2010) found that sparsely planting wetland tree seedlings had no significant effect on plant species richness or cover. Over four years after planting, there was no significant difference in any measured vegetation metric between planted and unplanted wetlands. Metrics included: total plant species richness; total vegetation cover; proportion of wetland-characteristic, herbaceous and woody plant species; and relative cover of wetland-characteristic, herbaceous and woody plants. The study does not report data for planted and unplanted wetlands separately (see Action: Restore/create marshes or swamps (multiple interventions) for combined data). Methods: In 2001, baldcypress Taxodium distichum and swamp tupelo Nyssa biflora seedlings were planted (≥5 m apart) into eight depressional wetlands. Eight nearby wetlands were not planted. Earlier that year, all 16 wetlands received the following interventions: plugging drainage ditches, cutting and removing non-wetland trees, and treating tree regrowth with herbicide. Vegetation was surveyed before (2000) and for four years after (2001–2005) planting, in 0.1-ha plots (3–5/wetland) and 4-m2 quadrats (8–12/wetland).

    (Summarised by: Nigel Taylor)

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