Environmental factors and recoveries of vegetation and terrestrial arthropod fauna were surveyed at the reforested site with Pinus thunbergii and Sarothamnus scoparius in comparison with the abandoned site under the natural succession after a forest fire. In reforested site, S. scoparius had grown to a dense thicket rapidly and dominated in vegetation. Consequently, diurnal ranges of air temperatures on the ground decreased, while ground-coverage ratio increased. From five years after reforestation, S. scoparius began to die and shrub layer degenerated backing to early stage. The year-to-year changes of the populations of terrestrial arthropods, especially Formicidae, several species of Gryllinae, Blattela nipponica and cursorial araneid spiders were different between in the reforested site and in the abandoned. Predominance and rapid death of S. scoparius affected the structure of arthropod community as one of the key environmental factors.

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Nitrogen fixation activity (ARA) in a wasted forest was determined by using th acetylene reduction technique. In the investigated plot, 62% of the ground surface was covered by vegetation, but 38% of that was bared. In the vegetation covered area, about 75% of total nitrogen and 98% of above ground nitrogen was accumulated respectively. While 0.94 kg·m^-2 of litter was accumulated, ARA of that was lower in vegetation covered area. As a compare with that, the significant ARA of blue-green algae occurred in the surface soil of bared area.
Total nitrogen fixation was estimated to be 215.43 mgN₂·80 m^-2·day^-1 in the investigated plot with the theoretical conversion ratio 3: 1, and about 89% of total fixation was in bare area. The recovery of ARA after re-watered of air-dried (below 5% of moisture content based on dry matter) surface soil was investigated. It was recognized the recovery of ARA was started about 8-hrs after re-watered in algaes and lichen.

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For estimating the effects of hillside works on soil reformation, undisturbed and disturbed soil samples were collected from a hillside works and their circumferences in granite region. Soil properties such as soil pH, total carbon content, total nitrogen content, solid ratio, specific gravity, volume of non-capillary pore (<pF1.8), volume of coarse capillary pore (pFl.8 ⋅2.7), volume of fine capillary pore (pF2.7 <), sandparticle content (0.074-2 mm in diameter) and fine fraction content (0.074 mm> in diameter) were measured. Comparing the individual soil property of both areas in relation to the lapsed years after hillside works, it was judged that the soils on the hillside work areas would gradually approach those on their circumferences (KUM-LUNG, and TAKEDA, 1991). In this paper, to estimate the soil reformation syntheti-cally, the soil properties are subjected to principal component analysis. Results showed that principal component analysis was a useful method to estimate the degree of soil reformation at the hillside work area. Besides, it was confirmed that solid ratio and total carbon content were closely related to the degree of soil reformation at the hillside work areas.

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