林木生长与养分动态模型研究 Ⅴ.杉木林养分曲线

Dynamic Models of Forest Growth and Nutrition Ⅴ.Nutrient Curve of China-fir Forest

对杉木二耕连栽林地、灌丛砍伐后头耕林地和阔叶林砍伐后头耕林地三大类型杉木林养分含量进行了研究．结果表明：杉木器官氮、磷、钾的含量存在显著差异，其含量按从多到少排列的顺序为：叶、枝、皮、根、干；杉木树体养分的平均含量Ｃ 随林龄ｔ增大而递减，递减速率与立地指数Ｓ呈正相关；杉木林养分吸收的总量Ｘ 随ｔ和Ｓ增大而递增，高立地指数Ｘ－ｔ曲线的斜率随ｔ增加而递减，说明杉木林幼、中龄时期养分供给的重要性．养分吸收曲线可反映不同生长时期林木吸收养分的相对强度，给出达到相对应生长量的净养分需求量，在林木营养动态管理中具有重要的理论和实践意义．

Samples were taken from China fir forests on three land types classified according to the way of previous land utilization:2nd rotation after China fir plantation; first rotation after shrub and bushes; and first rotation after broadleaf trees. The analytical results show that there are significant differences in the concentration of nitrogen, phosphorus and potassium in different organs of China fir tree with the order:leaf>branch>bark>root>trunk. The average nutrient concentration in China fir tree ( C ) decreases with the increase of tree age (t) , with a decreasing rate positively related to the forest site index (S) . The total quantity of nutrient uptake by forest ( X ) increases with the increase of t and S ,while the gradient of the X t curve decreases with the raising of t ; indicating the high importance of forest nutrition in the young and middle age periods. The nutrient uptake curve can be used for determining both the relative intensity of nutrient uptake and the net quantity of nutrient demand relating to forest growth at different forest growing stages, which is thus of high significance both in theory and practice in the dynamic management of forest nutrition.