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AbstractBranch growth in Larix gmeliniiwas estimated by several methods. Sample trees were felled in Laoshan (northeastern China) and Sapporo (northern Japan). Estimates of the annual woody growth of branches calculated by the growth ratio of the cross-sectional area of each branch base were found to be lower compared with those calculated by a detailed method, in which branch growth was estimated by growth-ring analysis of radial segments in different age classes. A linear relationship was observed between the annual woody growth/whole branch mass ratio and the relative depth within the crown (RDC), where the distance between the treetop and crown base was set to 1.0. The total annual woody branch growth of each tree was estimated using this relationship by multiplying the ratio by the whole branch mass at a given RDC and adding the products from the treetop to the crown base. Alternative estimates were obtained using the total branch growth, defined as the annual woody growth plus leaf mass, and the 1 − RDC relationship. Estimates obtained by these methods were similar to those obtained by detailed growth-ring analysis of branches. Estimates obtained by the growth/mass ratio for only the stem within the crown were also compared with those obtained by detailed growth-ring analysis.

AbstractWe studied the effects of line thinning on stand structure, microclimate and understory species diversity of two Cryptomeria japonicaD. Don plantations in south-central Japan. In each of two study sites we compared stand structure between the thinned stand and an adjacent unthinned stand and found that line thinning increased the growth rate of residual trees such that stand basal area may recover within 10 years after thinning. In the thinned stand, more open canopy conditions resulted in higher maximum temperatures on the forest floor during the early growing season than in the unthinned stand. The thinned stand had greater understory plant species richness and biomass than the unthinned stand. This study suggested that line thinning could potentially enhance biodiversity while simultaneously increasing tree-growth rates in overstocked Cryptomeria japonicaplantations.