No abstract

The number of Sustainable

In this study, shifts from the current forest physiognomy to a target forest physiognomy were modeled by applying the concept of zoning simulation. The objective was to present the process of generating management options for man-made forests in Kanagawa Prefecture, Japan. The assessment method was a wide-ranging and long-term simple simulation based on several indicators, such as geographical distribution and tree species, and adapted the concept of changes in forest physiognomy. A headwater forest in Kanagawa Prefecture, which covers an area of about 3784 ha and consists of 4445 forest stands, was investigated. Four plans were established based on the present state of the forest stands. The results indicated that factors for expressing forest physiognomy and their expression methods should be determined, and physiognomy models should be constructed to establish the actual state of the forests in each region. With this simulation, it is possible to forecast long-term changes at forest stand and basin levels for each scenario. However, only data from forestry register were used in this study, and it is expected that different results would be obtained by conducting a determination of stand position in the forest physiognomy together with a field survey.

The aim of the study was to clarify the situation of vegetation recovery on landslide slope in Tanzawa Mountains, Kanagawa prefecture. The landslide surface conditions, tree species and condition of their growth in four landslide sites were investigated. The study results are as follows. A large number of invaded trees are growing on uneven landslide surface. On landslide slope in broad leaved forest more trees can invade than in conifer forest. Small trees may grow easily close to bigger trees. On the periphery of the landslide area, many trees are growing because of rather stable surface soil. Trees can grow on the crack of bed rock without soil layer. On the bare soil surface and smooth bed rock, trees can not invade. On the bottom area and unstable area surface, trees can not also invade and grow.

and ABE, Kazutoki: Effects of thinning in Cryptomeria japonica D. Don stand on its root growth and function of preventing shallow landslide Abstract: Root distribution was investigated targeting eleven Cryptomeria japonica D. Don in thinning stands and non-thinning stands. Whole root systems of the each investigated trees were dug up carefully in the field. And root diameter and length of all roots at every 10 cm interval to depth direction and at 50 cm interval to radius direction. As a result, the whole root volume of the one tree has a good correlation with its trunk volume index and tree number density, respectively. And the amount of roots growing in the sliding surface of the landslide bottom and sides were not increased with increasing stand age. This means that the leading idea so far that the forest function of preventing shallow seated landslide is caused by roots growing on the sliding surfaces might not be correct. We assumed that the forest function of preventing landslide could be generate by suppressing deformation and cracks of the surface soil layer by the large amount of roots growing in it. The root volume in surface soil layer was calculated by the data of Cryptomeria japonica D. Don root distribution. We found that the root volume of surface soil layer in a thinning stands was much more than non-thinning stands from 10 to 30 year old. It is consistent with the relationship between number of the shallow landslides that occurred in younger forests and the stand age.