We investigated the distribution and physical characteristics of volcanic ash in periods of heightened volcanic activity (1972 to1992) and low activity (1993 to 2008), and examined changes caused by ebb and flow of volcanic activity at distances of 2.7 km, and 3.8 km from the Minamidake crater of Mount Sakurajima in the northern flank of Mount Sakurajima. The annual average thickness of the volcanic ash layer during heightened activities was 2.5 and 9.5 times greater than that measured during low activities, respectively. The dry density of the volcanic ash layer was 1.31 g/cm³ and 1.74 g/cm³ during the period of heightened activities and it was 1.19 g/cm3 and 1.57 g/cm3 during the period of low activities, respectively. The median diameter of solid particles in the volcanic ash layer was 0.16 mm and 0.33 mm during the period of heightened activities and it was 0.12 mm and 0.28 mm during the period of low activities, respectively.

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We tried the following thinning in the stands of the Muramatsu coastal forest (Ibaraki Prefecture) where thinning was delayed; we selected preserved trees of a number corresponding to the canopy heights expected in the future, we thinned around these trees and gave them space for future stands, and we left trees that would have little influence over the preserved trees as a kind of buffer to mitigate the influence of the salty sea wind. It was thought that this thinning method suppressed deterioration from salt sea winds of preserved trees, because the preserved Trees had not declined in spite of experiencing strong sea winds several times. However, we could not improve the height/dbh ratio or the crown length ratio of the preserved trees. It was thought that we had chosen more preserved trees than were necessary, as we had estimated the future canopy heights lower than they actually were. We also had to review the preserved trees promptly when the canopy heights exceeded our forecast and we had to do additional thinning.

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This paper addresses present conditions of revegetated steep slopes susceptible to shallow landslides; and temporal changes in the role of root networks in preventing shallow landslides due to vegetation recovery in abandoned forests after plantation clear cutting. The study site is 0.89 km² and is located near Kuma-mura, Kumamoto Prefecture. To conduct vegetation surveys of present revegetation conditions, we installed quadrats on four slopes: three with steeps lopes of not less than 40 degrees and one with a relatively gentle slope of 30 degrees. Vegetation on steep slopes prone to shallow landslides was poorer than that on the relatively gentle slope. When clears slope are reforested immediately after harvesting, the prevention function increases over time and is restored after approximately 20 to 30 years. Conversely, on slopes abandoned after clear cutting the prevention function is restored after 50 to 60 years due to the slower processes of natural vegetation succession. This indicates that the risk of landslides on steep slopes in abandoned plantations persists for 40 to 60 years after abandonment, considerably longer than in actively managed and re-planted forestry plantations

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By using new high-resolution satelite imagery , it is possible to detect forestland use structure and to assess environmental change more easily than with conventional lower resolution satellite data. However, due to the high spatial resolution, automatic classification of such imagery based only upon the spectral characteristics of the features can become difficult, especially, in spectrally homogeneous areas. Object-based imagery processing techniques overcome this problem by incorporating both spectral and spatial characteristics of objectives. In this research, an object-oriented eCognition's classification scheme was developed which used a DTM with IKONOS imagery for the initial segmentation and subsequent object classification. In the multi-resolution segmentation process, the influence of the DTM and multi-spectral bands on object generation was controlled by layer weight, scale parameters, the amount of color and shape factors. Results indicate that object-oriented approaches have great potential for improved site-specific operational planning and monitoring system in decision-making processes for timber harvesting strategy.

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Protected forests require management strategies that differ from productive forests, but it is necessary to integrate management of both forests from a landscape perspective. This integration is necessary for protected forests to be managed in the most economical and sustainable way possible, and to make sure that management of adjacent productive forests does not negatively affect protected forests. Traditional approaches to forest management planning do not offer this integration because they lack a holistic and spatial approach. In this paper the author describes the development of a spatial decision support system using GIS, and harvest schedule/allocation model, which allows simulation of potential forest resource management activities from a landscape perspective. This approach combines landscape perspective with improved analytical tools. It enables resource managers to design and demonstrate the long-term conservation outlook of forest resources under alternative management strategies with multiple objectives.

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