5:15 PM - 6:30 PM
[MIS06-P04] Mean residence time of leaf nitrogen and leaf longevity of hinoki cypress (Chamaecyparis obtusa) under nutrient-poor soil
Keywords:mean residence time of leaf nitrogen, leaf longevity, leaf production, hinoki cypress, organic horizon
Mean residence time of nitrogen in organic horizon (A0N-MRT) was used as the index of soil nutrient status. A0N-MRTs ranged 5.4 to 38.3 years that were longer than those in other stands of hinoki cypress. Leaf longevity and leaf-N MRT increased as A0N-MRT increased. Leaf production and leaf-fall nitrogen mass decreased with increasing A0N-MRT. There were no significant relationships between A0N-MRT and nitrogen resorption, leaf biomass, leaf nitrogen mass, nitrogen concentrations of fresh-leaf and leaf-fall. Nitrogen resorption was higher than that in other stands of hinoki cypress. It was suggested that nitrogen resorption did not significantly correlated with A0N-MRT because of high resorption rate in all plots. These findings indicated that hinoki cypress under nutrient-poor soil to maximize mean residence time of leaf nitrogen increased nitrogen resorption before leaf-fall first, and additionally, altered leaf longevity by changing leaf production along a soil nitrogen gradient.