0023-6152

AA00697606

23734

査読無

0023-6152

AA00697606

Seasonal change of the nest distribution of Formicayessensis in the hill and biotic and abiotic environmental conditions of nest sites were investigated in red pine stands in Gyeongsang-Nam-Do, Korea in 1973-77. The nests scarcely occurred in the upper zone of slopes and concentrated in the lower and middle zones. The distribution of nests changes seasonally but the density per unit area is relatively constant (0.014-o. 022 per m^2). The active nests increase in number from spring to summer by budding, then decrease in autumn by abandonment of nests. The life span of nests was l-4 months in most cases. The abandonment occurs more frequently in newly founded and revived nests. Abandoned nests are re-utilized. the number of times the same nest was utilized being ranged between 1 and 11. The humidity above ground and soil moisture are important factors for establishing nests. The content of organic matters was higher in soils at the lower and middle zones inhabited by the ant than in the upper zone. While the content of the exchangeable Ca was lower in the former than the latter. In the upper zone the density of pine trees is relatively low and that of Zoisia is higher than the middle and lower zones. Such conditions are unfavourable for establishing nests. The lower and middle zones, on the contrary, are favourable because of the relatively high density of pine trees, but sufficient light intensity and presence of suitable plants for nest cores such as long graminaceous grasses. Arundinella hirta, Pinus densijlora (red pine trees) and Miscanthus sinensis f. purpurascens as well as stones serve as the core for building nests.