南亚热带格木和红椎凋落叶及细根分解特征

Decomposition characteristics of leaf litter and fine roots of Erythrophleum fordii and Castanopsis hystrix in subtropical China

采用原位分解法对南亚热带格木(Erythrophleum fordii)和红椎(Castanopsis hystrix)人工纯林的凋落叶和细根分解动态及凋落叶和细根分解速率之间的相关关系进行了比较研究。结果显示,格木、红椎人工林凋落叶和细根分解系数分别为0.98a^(-1)、0.88a^(-1)和0.65a^(-1)、0.59a^(-1)。格木、红椎凋落物分解主要受凋落物自身化学性质的影响,而与林分内环境条件的关系不显著。分解初期,凋落叶和细根的质量损失均与氮含量显著正相关(R^2分别为0.525和0.549),与C/N比显著负相关(R^2分别为0.764和0.361);而分解后期,凋落叶和细根的质量损失均与氮含量显著正相关(R^2分别为0.565和0.511),与C/N比、木质素含量、木质素/N比显著负相关(R^2分别为0.482和0.574;0.525和0.519;0.523和0.486)。格木、红椎凋落叶分解速率和细根分解速率表现出明显的正相关性,这主要归因于凋落叶、细根基质质量对凋落叶分解速率和细根分解速率的影响具有明显的相似性。

We determined the in situ decomposition of leaf litter and fine roots of Erythrophleum fordii and Castanopsis hystrix in subtropical China using the nylon mesh-bag method. The results indicated that the decomposition coefficients for leaf litter and fine roots of E. fordii and C. hystrix were 0. 98 a^-1and 0. 88 a^-1and 0. 65 a^-1and 0. 59 a^-1,respectively.Decomposition rates for leaf litter and fine roots were primarily influenced by the chemical properties of the litter,rather than by the environmental factors in the plantations. During the initial phase,the percentage of dry mass loss was positively correlated with N content（ R^2= 0.525 and 0.549,respectively） and negatively correlated with the C / N ratio（ R^2= 0.764 and 0.361,respectively） for leaf litter and fine roots. During the late phase of decomposition,decomposition rates were positively correlated with N content（ R^2= 0. 565 and 0. 511,respectively） and negatively correlated with lignin content（ R^2= 0.525 and 0.519,respectively）,C / N（ R^2= 0.482 and 0.574,respectively）,and lignin / N ratios（ R^2= 0.523 and0.486,respectively） for leaf litter and fine roots. The significant correlation between leaf litter and fine root decomposition rates could be attributed to the similar effects of chemical properties on decomposition rates.