Allometry and Competition between Saplings of Pic

Authors: KUBOTA YASUHIRO HARA TOSHIHIKO

Publish Date: 1996/05/01

Volume: 77, Issue: 5, Pages: 529-538

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Abstract

YASUHIRO KUBOTA TOSHIHIKO HARA Allometry and Competition between Saplings of Picea jezoensis and Abies sachalinensis in a Subboreal Coniferous Forest northern Japan Annals of Botany Volume 77 Issue 5 May 1996 Pages 529–538 https//doiorg/101006/anbo19960063The crown shape and the mode of competition between saplings 2m in height of the two conifers Picea jezoensis and Abies sachalinensis of a subboreal forest northern Japan were investigated based on the diffusion model A model for individual sapling growth considering both inter and intraspecific competition was developed The effect of speciesspecific crown shape on the sapling growth and competition of the two species were examined Picea jezoensis and Abies sachalinensis saplings had deep conic and shallow flat crowns respectively Picea jezoensis had more foliage mass than Abies sachalinensis of the same sapling mass It was suggested that the Picea jezoensis sapling has a high cost for assimilation–respiration balance under dark conditions of closed canopies whereas the Abies sachalinensis sapling maintains effective assimilation even under suppressed conditions Widely spaced saplings such as gap successors of Picea jezoensis had a greater relative growth rate a0 than widely spaced Abies sachalinensis The crown shape of saplings of the two species shows different adaptations for efficient persistence in the subboreal forestSaplings of Picea jezoensis and Abies sachalinensis were not uniformly distributed but aggregated in different sites as the saplings grew indicating habitat segregation between the two species at the sapling stage Intraspecific sapling competition was onesided in each of the two conifers Interspecific sapling competition was onesided in the direction only from Abies sachalinensis to Picea jezoensis Therefore asymmetric competition prevailed at the sapling stage of the two species These results contrast with weak symmetric competition or the almost absence of competition between trees ≥2m in height of the two species Kubota and Hara Annals of Botany76 503–512 1995 The mode of competition changed with the lifehistory stage from the sapling intense and asymmetric to the tree weak and symmetric or almost absentIn conclusion 1 asymmetric and intense competition between saplings brought about habitat segregation between the dominant species Picea jezoensis and Abies sachalinensis in the early stage of lifehistory 2 therefore the coexistence of Picea jezoensis and Abies sachalinensis of the subboreal forest was determined by the boundary conditions for the growth dynamics of the trees as segregation of establishment sites resulting from asymmetric and intense competition between saplings 3 then the species composition of the forest was maintained by weak symmetric competition or the almost absence of competition between trees

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