2021 Volume 38 Issue 1 Pages 119-129
We investigated climate factors affecting the tree-ring width and seed production of Abies mariesii in a snowy subalpine coniferous stand in a 1-ha permanent plot for the Monitoring Sites 1000 Project in Otanomosu-daira in the Shiga Highland Biosphere Reserve, central Japan. Wood cores （5 mm diameter） were taken at a trunk height of 50 cm from 40 individuals with various diameters ［mean diameter at breast height, 25.2 cm （range, 9.4-49.4 cm）］ using an increment borer. Crossdating, standardization, and autoregressive modeling were performed on a tree-ring time series to develop a residual chronology representative of the habitat. Relationships between the chronology and climate factors during the period 1937-2018 were assessed with Pearsonʼs correlation analysis. The tree-ring width was positively correlated with the temperatures in November of the previous year and April of the current year; it was negatively correlated with the minimum temperature in July of the previous year. It also had significant positive and negative correlations with the precipitation in May and July of the previous year, respectively. A generalized linear model （GLM） was used to analyze the relationship between tree-ring width and seed production, and the effects of climate on seed production during the period 2006-2018. The GLM showed that there is a trade-off between tree-ring width and seed production in a given year. However, there was no correlation between seed production in a given year and tree ring width in the following year. Spring and autumn temperatures （April, May, October, and November） had a negative effect on seed production in the following year, and the mean daily minimum temperature in August had a negative effect on seed production in the current year. The summer temperature （July and August） positively affected seed production in the following year. June and August precipitation had a negative impact on seed production in the current year. The insolation duration in May had a negative effect on seed production in the current and following years, while that in April and June had a positive effect on seed production in the current year, and that in July had a positive effect on seed production in the following year. These results suggest that increases in temperature in the spring and autumn due to global warming will encourage tree-ring growth and reduce seed production of A. mariesii in the stand. They also suggest that increases in summer temperature and insolation duration would promote reproduction;however, seed production may be suppressed by reduced spring insolation duration and increased summer temperature and rainfall. The relationship between tree-ring width and seed production, and the effects of climate factors thereon in the A. mariesii population, are likely to change further with future climate change. Continued monitoring is needed for the early detection of such influences.
