GROWTH-PATTERNS OF TREE HEIGHT AND STEM DIAMETER IN POPULATIONS OF ABIES-VEITCHII, A-MARIESII AND BETULA-ERMANII

(1) The growth patterns of tree height and stem diameter in crowded Abies veitchii, A. mariesii and Betula ermanii populations were investigated based on the diffusion model for growth dynamics in size-structured populations. (2) Size-dependent growth was found in each species, but the pattern was different between the species. Small, suppressed individuals of Abies spp. showed little growth in tree height but grew in stem diameter. In small, suppressed individuals of B. ermanii, the converse was found. (3) The diffusion model revealed that stem diameter growth of Abies spp. and tree height growth of B. ermanii are affected only a little by competition between individuals even under crowded conditions, and thus that growth in these dimensions is determined in a genetically strict manner for each species. These growth patterns correspond to the life-history traits and the successional status of Abies spp. (shade-tolerant late-successional species) and B. ermanii (a shade-intolerant early-successional species). (4) This study indicates the quantitative differences of assimilate partitioning between tree height growth and stem diameter growth in size-structured plant populations in relation to the characteristics and successional status of species.