Dry-matter production and its changes before and after thinning were studied in a young, four to seven years old, plantation of Alnus sieboldiana. Estimation of net production rates was made from the balance sheet of organic matter in the study plantation. In order to produce this balance sheet, a tree size survey, destructive sampling and litterfall measurements were made. In addition, pollen production and root biomass were measured. The biomass of both woody parts (stem plus branches) and leaves after thinning dropped to47% of that before thinning, which corresponded to the reduction in basal area by thinning (45%). The mean annual net production rate over a2-yr period amounted to1503g/m²·yr for aboveground parts and1806g/m²·yr or more for the whole plantation including roots. This average of aboveground parts was equal to that before thinning. Although the annual production rate of aboveground parts in the 1st year after thinning was reduced with the decrease in leaf production, the value of aboveground parts in the 2nd year was restored beyond the original value before thinning. Despite the fall in leaf productiondue to thinning, the annual production rate of woody parts increased slightly after thinning due to the increased branches. The ratio in the annual production rates of total aboveground components to leaves, which reflects the leaf efficiency, was raised by thinning to a value1.4times higher than before thinning, and the ratio of woodyparts to leaves was doubled. This rise was found in only the first year after thinning.

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Distructions of snow-patch vegetation caused by the mountaineers hiking, or excess development on its alpine meadow has become the recent serious problem on the heavy snow region on alpine area.
Toward the solution of this issue, the summit area of Mount Makihata, in Niigata Prefecture, 1, 967meters above sea level, emerged as one of the severe instance of damaged place. Revegetation has been experimented at snow patch mainly by the volunteer workcamp under economical limitation and technical restriction; nonenterprise or little government undertaking level.
Several sowing and transplant experiments have been conducted for seventeen years with native harbaceous plants, simultaneously reviewing, surveying and analysing on the structure of distruction of snow-patch vegetation.
Following results were obtained: effective native revegetation materials at Mount Makihata and adaptable for snow-patch vegetation are such as Carex omianaFR. ET SAV. andMoliniopsis japonicaHAYATA.
In addition, urgency of revegetation on south side slope has been pointed out, according to the analysis of the environmental factors about both natural and artificial rehabilitation.

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Vigorous and healthy trees can refresh feelings and help provide peace of mind. However, there is no criteria for measuring a tree's vigor and thus, it is necessary to establish a method for such quantitative evaluation and systemize it.
In this stydy, a tree's vigor was evaluated photometrically using an infrared television carema. The tree's vigor was evaluated according to the brightness of it's NDVI picture. The psychological effects on people looking at trees was investigated according to the Analytic Hierarchy Process and the SD method. As a result of this, the photometric evaluation system's effectiveness was determined. The effect of the variation in the vigor of trees on the perceived quality of landscape was evaluated.

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