Spatial distribution patterns and incidence-severity relationships of Seiridium canker in young hinoki cypress stands.

概要

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Spatial distribution patterns of Seiridium canker of hinoki cypress (<I>Chamaecyparis obtusa</I>) and incidence (proportion of infected trees) -severity (mean lesion number) relationships of the disease were investigated in young hinoki cypress stands in Hyogo Prefecture. Spatial distribution of infected trees were aggregated at early stage of epidemics, then the degree of aggregation decreased with the progress of epidemics as most trees were infected. The distribution patterns of infected trees were best described by negative hyper-geometric distributions. Distributions of lesions were highly aggregated consistently through the survey, and the distribution patterns were fitted by negative binomial distributions. Disease incidence could not be used to estimate the mean lesion number for the fluctuating mean lesion number to the same incidence. Relationships between incidence and lesion number, however, could be described by the individual number-colony number model of Yamamura. Prediction of further epidemics would be possible by monitoring the incidence and lesion number on one occasion. Large sample sizes were calculated to be necessary for estimating mean lesion number for their highly aggregated distributions.
日本森林学会の論文