Effect of size structure, forest floor type and disturbance regime on tree species composition in a coniferous forest in Japan
1994
Takahashi, K.
1 Spatial patterns of two conifers, Abies sachalinensis and Picea glehnii, were surveyed in an Abies-Picea forest in Hokkaido, northern Japan. 2 A 150-m x 150-m plot was divided into 10-m x 10-m stands which were classified as soil (SL), rock-soil (RS) or rock-moss (RM) type stands, based on soil depth and moss cover. The soil depth and Sasa (bamboo) cover decreased, and the moss cover increased from SL through RS to RM type stands. 3 The numbers of Abies trees increased while those of Picea trees decreased and sizes of both conifers decreased from SL to RS to RM stands. There were more fallen trees in the RS and RM type stands. 4 Regeneration of Picea occurred almost exclusively on fallen logs, whereas Abies grew at any microsite except under Sasa. 5 The densities and diameters of the fallen logs decreased in the order, SL, RS, RM type stands. The total volume of seedlings present per unit of fallen log area decreased in the same order. This was due exclusively to significantly higher regeneration on larger diameter logs. No difference was found among the three floor types in abundance of seedlings on the same diameter logs. 6 The paucity of Picea in the RM type stands may be ascribed primarily to an unstable forest floor, which raises the frequency of disturbance and therefore reduces the size of fallen trees. The small fallen logs do not provide suitable seedbeds for Picea which thus regenerated poorly. Abies regenerated well on the forest floor of RM stands since there is little Sasa cover and the larger gaps are present.
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