The coastal areas of the Sendai Plain have been constructed with embankments to promote the development of the root system of Pinus thunbergii, which is the main tree species planted in coastal forests, to strengthen their tsunami mitigation function. However, the planted black pine trees have suffered from poor growth probably due to some adverse soil conditions. This study established three quadrates in the 2014 planting area at a coastal forest restoration site in Natori City, Miyagi Prefecture. We conducted tree-by-tree and multi-point soil surveys to assess the growth condition of the planting bases. The tree-by-tree survey results showed a significant difference in the growth of P. thunbergii between the three-square sections, even though they were planted in the same planting year. The results of multi-point soil surveys showed completely different soil physical and chemical properties among three quadrates, and that the poor growing areas showed consolidated subsoil, high moisture content, low pH, and high EC. Spatial variation in soil parameters was large within the quadrate, suggesting that highly heterogeneous soil parameters affected the plant growth. Multiple regression analysis was conducted using the growth status of black pine as the objective variable, and significant multiple regression equations were obtained in all quadrates. Although statistically significant equations indicated effects of soil properties on the growth of black pines, direct concerns on the plant growth was not clear.

After the Great East Japan Earthquake, tree-planting areas on the artificial ground, such as tsunami evacuation hills and road embankments have expanded. Since the properties of the artificial ground would depend on several factors such as embankment materials and construction methods, these would cause the variation of growth of planted trees by sites. In this study, the relationship between the growth of planted broad-leaved trees and the several ground properties were investigated at tsunami evacuation hills and road embankments constructed in Iwanuma City, Miyagi Prefecture, to make clear the main tree growth differentiated factors. Growth of tree seedlings in five embankments differentiated in times of construction and planting were measured over several years and its ground properties such as hardness, texture, nutrient content, and pH, were compared. The growth differences among embankments were related to the properties of the embankment materials rather than ground hardness. The growth of evergreen tree species, such as Machilus thunbergii, Quercus myrsinifolia, Q. salicina, Q. glauca, Q. acuta, Camellia japonica, and Ilex integra, slowed down on the embankments with acidic or alkaline reformed soils that contain fewer clay particles, organic matter, and exchangeable Ca and Mg. It was also suggested that the ground hardness could explain partial growth differences within a site. Within an embankment with the same material, slow growth of planted trees tended to occur on extremely hard or soft grounds.