[Characteristics of nutrient accumulation and vertical spatial distribution in plantation with different stand densities].

The growth, biomass, nutrient content and accumulation as well as the vertical distribution of nutrient accumulation in plantation across densities of 1800, 3000, 4500 trees·hm were stu-died in order to provide scientific basis for efficient cultivation of plantation. The total amounts of nutrients accumulated in plantation with 1800, 3000, 4500 trees·hm were 1311.57, 2531.55 and 2307.33 kg·hm, respectively. There were significant variations among different densities. Under the same density, the order of nutrient content and accumulation in plantation was total N > total K > total Ca > total Mg > total P. Moreover, the amount of nutrients in trunk and bark decreased with the increases of tree height. The amount of nutrient accumulation in persistent withered branch and leaf were allocated from middle to the upper part of tree, while the opposite was observed for fresh branch and leaf. N accumulation increased with the increases of stand densities, while the other nutrients first increased then decreased. The order of the amount of nutrient accumulation in trunk, bark, root, persistent withered branch, persistent withered leaf and litter among different densities was 4500 > 3000 > 1800 trees·hm, and was 3000 > 1800 > 4500 trees·hm in fresh branch and leaf, and 1800 > 3000 > 4500 trees·hm in understory. Under the densities of 1800 and 4500 trees·hm, the nutrient distribution ratio in bark was the largest, accounting for 21.6% and 19.4%. In 3000 trees·hm, the distribution ratio of fresh leaves reached its maximum, accounting for about 22.9%, and the next was fresh branches, which had a distribution ratio of about 17.8%. 3000 trees·hm was the most appropriate density for nutrient accumulation and distribution in plantation.