Build your own seeded coir logs for use in shoreline restoration? Part 2
Seeding instead of plug-planting shorelines could reduce the cost of restoring shorelines. Study looks at the role of peat moss in seed retention and seedling establishment.
Part 1 of this Michigan State University Extension article detailed the construction and installation of home-made, seeded coir logs for use in a study conducted on the Keweenaw Peninsula by Michigan Technological University.
For each of the two projects involved in the study (Marsin and Sand Point), the sections of coastline to be restored were divided into three adjacent zones running parallel to the water’s edge; 1) emergent, 2) wet meadow and 3) shrub. The emergent zones and shrub zones consisted of ten, 10-foot long by 1-foot diameter “logs” as described in Part 1. The wet meadow zone consisted of ten, 10-by-10 foot restoration plots, covered with a dual layer of coir and jute matting. Alternating sets of logs and wet meadow plots were treated with a layer of milled peat moss to see if it had any effect on seed retention or seedling establishment.
Germination and establishment of wetland vegetation was successful at both sites and the wet meadows in particular were heavily vegetated with a diverse mix of wetland plant species. Fluctuating water levels had a negative effect on the emergent and shrub zone logs. The addition of peat moss had mixed effects between the two sites. At Marsin, it had virtually no effect on plant establishment, cover or diversity and many of the no peat plots had greater vegetative cover. At Sand Point, there was also little difference noticed between the peat and no peat wet meadow plots but there was a definite positive effect of peat addition on the vegetative cover on the emergent logs.
Given these preliminary results, it appears that seeds can be used as a cost-saving method for establishing freshwater coastal wetland vegetation. However, the success of this project was greatly affected by fluctuating water levels in Lake Superior. The low water levels allowed the wet meadow and emergent vegetation to get established so that, once the water levels came back to “normal”, the plants had extensive root systems to keep them in place. The low water also resulted in the death of emergent vegetation and shrubs at one site, so modification of the methods used would be necessary for future projects.
Other articles in this series: