杉木林凋落物产量、分解率与储量的关系

在福建三明采用2种方法测定27a生杉木林的杉木叶和小枝凋落物的分解率．采用网袋法(孔径0．5mm尼龙网袋)测定的杉木叶和小枝凋落物残留率Olson指数模型的分解系数(k值)分别为0．7692a^-1和0．2501a^-1，相应的第1年的分解率分别为53．66％和22．13％；另一种测定矗值的方法较为准确，是通过计算凋落物年产量与地面凋落物储量的比值得到，采用该方法计算的杉木叶和小枝凋落物的矗值分别为1．788a^-1和0．8622a^-1，分别是网袋法测定值的2．32和3．54倍，相应的第1年的分解率分别为83．27％和57．78％，分别是网袋法测定值的1．55倍和2．61倍．采用后一种方法测定的凋落物分解率可以解决尼龙网袋法测定分解速率结果偏低的问题．

RELATIONSHIPS AMONG LITTER PRODUCTION, DECOMPOSITION AND ACCUMULATION IN CHINESE FIR PLANTATION

Two approaches were used to assess the decomposition rates of leaf and twig litter of a 27-year-old Chinese fir plantation in Sanming, Fujian, China. Decomposition constants (k values) of Olson's exponential decay model of leaf and twig litter of Chinese fir, determined by mesh bag technique (0.5-mm-mesh nylon bag), were 0.769 2 a -1 and 0.250 1 a -1 , respectively, and corresponding weight loss of leaf and twig litter after the first year were 53.66% and 22.13%, respectively. Another approach introduced for determining litter decomposition rates, which is more precise, was to calculate the decomposition constant (k values) of Olson's exponential decay model through the ratio of annual litter input to forest floor mass. Decomposition constants (k values) of leaf and twig litter of Chinese fir calculated by this way were 1.788 a -1 and 0.862 2 a -1 , respectively, 2.32 and 3.54 times as much as those determined by mesh bag technique, respectively, and corresponding weight loss of leaf and twig litter after the first year were 83.27% and 57.78%, respectively, 1.55 and 2.61 times as much as those determined by mesh bag technique. Decomposition rates determined by the latter approach solved the problem of underpredicting litter decomposition rates by mesh bag technique. Fig 2, Tab 3, Ref 13