Interannual variability of leaf area index of an evergreen conifer stand was affected by carry-over effects from recent climate conditions

Despite the relevance of leaf area index (LAI) to forest productivity, few studies have focused on the interannual variability of LAI of an evergreen stand and its relationship with stand growth and meteorological factors. We estimated the change in LAI of an evergreen conifer (Chamaecyparis obtusa) stand over 19 years from a dataset using allometric methods. The LAI varied between 7.1 and 8.8 m2 m−2, with a 95% confidence interval of <1.1 m2 m−2 over the 19 years. This LAI range was maintained such that the gradual increase in leaf area (LA) of the largest trees counterbalanced the gradual loss in LA of the smallest trees. Meanwhile, more trees showed a temporary decrease in LA in years with low summer precipitation. The LAI and current-year mean temperature for July and August (TJA) were weakly correlated, whereas the correlation coefficient increased (r = 0.93) when LAI was correlated with the moving average TJA over the previous 6 years, which agreed with the estimated turnover time of canopy foliage. The annual stem biomass growth rate was significantly positively correlated with summer precipitation, but not with LAI. These results will be useful for refining models in studies on forest growth and global climate change.