Restoration of small marsh and evaluation of its effectiveness: A case study of nature restoration at Tsuguro Highland's marsh which aiming local community re-vitalization

<p>In south-west Japan, small marshes that have been developed and maintained due to human activities for livelihood are scattered, and they are hotspots for biodiversity. However, many of them have been degraded and/or disappeared due to succussion because of underuse of Satoyama resources. The authors tried to restore a small marsh at Tsuguro highland as a case study. And tried (1) to evaluate restoration work by comparison of the data of the environment and vegetation before and after the project, (2) to proceduralize a series of flows such as field data survey, evaluation, target setting, planning and design, construction, monitoring, (3) to promote the enjoyment of ecosystem services related to the restoration work to regional re-vitalization, and to evaluate them. First, in 2013, maps of vegetation, groundwater level, and light environment were drawn. It was clarified that (1) the groundwater level was too low in some part, (2) the light condition was inhibited by the tall forest those developed in and around the marsh, and (3) the water quality became nutrient rich, and the high-stem grass was growing thick. Then, a restoration plan which focused on the rise of groundwater level by pouring flowing water, improvement of the light condition by cutting trees, establishment of low and middle stem grass groups by topsoil removal, and excavation of ponds to diversify the environment was proposed. The project was implemented in 2014. The cut trees were used as a heat source for at a nearby hot spring facility. Also, nature restoration promotors were invited to the workshop of restoration work. In 2015, a survey was conducted and the data set before and after restoration was compared. As a result, dramatic improvement of the light condition, certain improvement of the groundwater level and water quality was recognized. The number of species of wet herb increased, and the target type of plant community (Phragmites australis community Lysimachia vulgaris sub-community) expanded. Through a series of project, useful procedures for the restoration of small marsh have been clarified. And contribution for revitalization of the area thorough effective use of biomass produced by restoration work and to increase the number of people interacting with urban areas was evaluated.</p>