Predicting dispersal-limitation in plants: optimizing planting decisions for isolated wetland restoration in agricultural landscapes

Published source details O’Connell J.L., Johnson L.A., Beas B.J., Smith L.M., McMurry S.T. & Haukos D.A. (2013) Predicting dispersal-limitation in plants: optimizing planting decisions for isolated wetland restoration in agricultural landscapes. Biological Conservation, 159, 343-354.
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This study is summarised as evidence for the following.

	Action	Category
	Modify crop farming practices in watershed to reduce pollution: freshwater marshes Action Link
	Retain/restore/create vegetation around freshwater marshes Action Link
	Remove surface soil/sediment: freshwater marshes Action Link

Modify crop farming practices in watershed to reduce pollution: freshwater marshes

A replicated, site comparison study around 2010 of 48 ephemeral freshwater marshes in Nebraska, USA (O’Connell et al. 2013) reported that marshes undergoing restoration (surrounding cropland abandoned and agricultural topsoil removed) contained a different plant community to natural marshes (surrounded by permanent grassland) and degraded marshes (surrounded by cropland), with lower cover of wetland perennial plants and fewer wetland perennial species than the natural marshes. Results summarized for this study are not based on assessments of statistical significance. After 1–12 years, the overall plant community composition differed between restored, natural and degraded marshes (data reported as a graphical analysis). Perennial wetland species were underrepresented in restored marshes (43% cover; 10.1 species/marsh) compared to natural marshes (56% cover; 13.0 species/marsh). However, restored marshes had greater cover of these species than degraded marshes (35% cover; species richness not reported). Annual wetland species were “slightly” overrepresented in restored marshes compared to natural marshes in terms of abundance (data reported as a graphical analysis only). However, there was a similar number of these species in restored marshes (8.2 species/marsh) and natural marshes (8.0 species/marsh). Methods: Around 2010, vegetation was surveyed in 48 ephemeral playa marshes (along two transects crossing each marsh, in both the cool and warm seasons). Sixteen of the marshes were undergoing restoration under the Wetland Reserve Program. This involved abandoning the surrounding cropland and removing eroded agricultural topsoil from the marshes. The study does not distinguish between the effects of these interventions. Of the remaining marshes, 16 were in natural catchments and 16 were in degraded, farmed catchments.

(Summarised by: Nigel Taylor)
Retain/restore/create vegetation around freshwater marshes

A replicated, site comparison study of 258 ephemeral freshwater marshes in central USA (O’Connell et al. 2013) reported that marshes within revegetated cropland contained a different plant community to natural marshes (surrounded by permanent grassland) and degraded marshes (surrounded by cropland), with lower cover of perennial wetland plants and fewer perennial wetland species than the natural marshes. Results summarized for this study are not based on assessments of statistical significance. After 1–20 years, the overall plant community composition differed between restored-catchment, natural and degraded marshes (data reported as a graphical analysis). Perennial wetland species were underrepresented in restored-catchment marshes (30% cover; 3.5 species/marsh) compared to natural marshes (47% cover; 5.0 species/marsh). However, restored-catchment marshes had greater cover of these species than degraded marshes (7% cover; species richness not reported). Annual wetland species were overrepresented in restored-catchment marshes compared to natural marshes in terms of abundance (data reported as a graphical analysis only). However, there was a similar number of these species in restored-catchment marshes (5.2 species/marsh) and natural marshes (5.4 species/marsh). Methods: Around 2010, vegetation was surveyed in 258 ephemeral playa marshes (along two transects crossing each marsh, in both the cool and warm seasons). Of these marshes, 86 were undergoing restoration under the Conservation Reserve Program (former cropland in catchment replanted to grassland 1–20 years previously; no intervention within the marshes), 86 were in natural catchments, and 86 were in degraded, farmed catchments. This study used a subset of the sites from (1).

(Summarised by: Nigel Taylor)
Remove surface soil/sediment: freshwater marshes

A replicated, site comparison study around 2010 of 48 ephemeral freshwater marshes in Nebraska, USA (O’Connell et al. 2013) reported that marshes undergoing restoration (agricultural topsoil removed and surrounding cropland abandoned) contained a different plant community to natural marshes (surrounded by permanent grassland) and degraded marshes (surrounded by cropland), with lower cover of wetland perennial plants and fewer wetland perennial species than the natural marshes. Results summarized for this study are not based on assessments of statistical significance. After 1–12 years, the overall plant community composition differed between restored, natural and degraded marshes (data reported as a graphical analysis). Perennial wetland species were underrepresented in restored marshes (43% cover; 10.1 species/marsh) compared to natural marshes (56% cover/group; 13.0 species/marsh). However, restored marshes had greater cover of these species than degraded marshes (35% cover; richness not reported). Annual wetland species were “slightly” overrepresented in restored marshes compared to natural marshes in terms of abundance (data reported as a graphical analysis). However, there was a similar number of these species in restored and natural marshes (8.2 vs 8.0 species/marsh). Methods: Around 2010, vegetation was surveyed in 48 ephemeral playa marshes (along two transects crossing each marsh, in both the cool and warm seasons). Sixteen of the marshes were undergoing restoration under the Wetland Reserve Program. This involved removing eroded agricultural topsoil from the marshes and abandoning the surrounding cropland. The study does not distinguish between the effects of these interventions. Of the remaining marshes, 16 were in natural catchments and 16 were in degraded, farmed catchments.

(Summarised by: Nigel Taylor)