Influence of Stand Density on the Increment of Leaf Biomass in the Young Cryptomeria japonica Stand before Canopy Closing

To clarify the density effect on increment of leaf biomass in young Cryptomeria japonica stand before canopy closing, we studied on the relationship between leaf biomass, stand density and stand growth. The study plot was a 8-year-old spacing experiment stand in Tokyo University Forest in Chiba. We used three blocks with density of 2500 trees/ha, two blocks with density of 3906 trees/ha and three blocks with density of 6944 trees/ha. The biomass of each block was estimated from the allometric relationship between diameter at breast height and each organ weight obtained from three sample trees. Leaf biomass was from 17 to 26 t/ha. Leaf biomass had good relationship to mean tree height and didn't differ apparently among the blocks with different densities. Leaf biomass ratio to aboveground biomass decreased with relative density, for example 45% on the block with relative density of 0.2 and 30% on the blocks with relative density of 0.5. Stem production efficiency tended to be large on the sample trees with high nitrogen content in leaves or stand in the blocks with high density. Accordingly trees in blocks with low density had high partitioning rate to other organs but stem, such as leaf and branch. These results suggested the density effect on the leaf development.