Case Study 2: Restoring wetland vegetation using transplanted soil (Brown and Bedford, 1997).

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Description of Experiment:

• This study looked at the effectiveness of transplanting soil from small remnant wetlands in drainage ditches to the restored wetland sites located in nearby marsh areas.
• Authors predicted that if remnant soils could be transplanted to restored areas, their relatively rich seed banks would produce greater species richness and cover of wetland plants following the establishment of hydrology.
• Focus was placed on land elevation in order to determine if transplanting remnant wetland soil could be an effective technique for wetland restoration at high elevations where drainage is more severe. Land elevations include: -15 cm, and -30 cm
• Two scales were used, a small-scale study and a large-scale study. In the small scale study the soil had 5 different treatments: undisturbed, sieved (soil without roots and rhizomes), disturbed, litter removed, and transplanted. In the large scale study the following soil plots were established: control, mowed, plowed, soil transplant.
• The following questions were asked in each study:

1. Can the number of wetland plant species that germinate and establish be increased by transplanting soil from remnant wetlands areas?
2. Does the inclusion of wetland plant rhizomes in the transplanted soil affect the species richness and abundance of wetland plants that become established?
3. How long do treatment effects persist?
4. Do the treatments increase the abundance of plant species known to be used as food sources by waterfowl and march birds?
5. Can these techniques be applied at the scale of whole restoration sites?

Results:

Small scale study

• Figure 2
• Figure 4

Conclusions/Future Research:

• If improvements from the soil transplanted plots do not occur longer than the first few growing seasons, soil transplantation is an unnecessary technique.
• The most important application of soil transplantation may be to control cattail invasion. In the large scale experiment, mean percent cover of Typha spp. was significantly higher in the plowed plots versus the mowed and soil transplanted plots. The authors concluded that transplanting wetland soil into the disturbed area during dike construction could improve the establishment of native species and decrease the probability of cattail invasion.