永久凍土地帯の森林の生態的特性

概要

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Severe winter cold and summer drought prevail on permafrost in Yakutis plain. The water penetration in a deep ground is prevented by permafrost, and thaw or rain water is retained in the active layer in which soil remains unfrozen in summer (about 60cm in depth in dense forests). Thus, the forest zone expands to the summer drought area in permafrost regions. Dahurian larch roots expand in the soil down to 5 to 20cm-depth. And the soil temperature and the water content at 20cm-depth were respectively 3.6℃ and 15 per cent on August 12. Thus, the low soil temperature and the low soil water content are among the most important factors limiting the tree species growing in dry and high latitudial permafrost regions. In the permafrost areas containing massive ice veins, clearing of forests causes the development of the thermokarst depression with steep sides and a flat floor covered with grass, called an alas. Regeneration of forests does not occur in alases. Forests contribute to prevent melting of the groundice. On the contrary, permafrost allows forests to grow even in summer drought areas. Thus, it appears that there is an intimate relation between forest and permafrost.
日本生態学会の論文
1974-06-30