Seasonal variations in light and leaf nitrogen distribution in a Cryptomeria japonica canopy
2004
Kobayashi, H. (Kyushu Univ., Fukuoka (Japan). Faculty of Agriculture) | Gyokusen, K.
We investigated seasonal variations in light and leaf nitrogen distribution in the closed canopy of a seven-year-old Cryptomeria japonica D. Don stand. Within the canopy, light intensity relative to full sunlight tended to decrease from June to December. In contrast to light intensity, the leaf nitrogen content of current-year leaves (expressed on area basis) tended to increase from June to September and then decrease from December to April. Because it took a long time for the Cryptomeria japonica leaves to mature, the leaf nitrogen content of the current-year leaves increased even though the leaves became more shaded due to canopy development. The leaf nitrogen content of the current-year leaves was positively and linearly correlated with light intensity within each season. However, the slope of the linear regression between leaf nitrogen content and light intensity differed between seasons. The slope of the linear regression increased from June to September, and then decreased thereafter. The y-intercept of the linear regression was almost constant throughout the year.
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