鼎湖山黄果厚壳桂粗死木质残体的分解

通过建立时间序列法、测定粗死木质残体的密度变化,研究鼎湖山黄果厚壳桂粗死木质残体三个直径(5~10cm、10~20cm和20~30cm)的分解过程,探讨粗死木分解过程中C、N元素及其C/N比值与分解速率的关系。结果表明粗死木质残体的分解常数K值随直径的增加从0.2225a-1呈指数降低到0.1257a-1,由粗死木质残体在分解过程中密度变化得出三个直径从小到大分解95%所需的时间分别为13a、19a和24a;黄果厚壳桂粗死木质残体在分解过程中不存在时滞效应,其树皮和心材的分解速度也相近,用单因素数指数方程能准确反映黄果厚壳桂的分解过程;与高纬度地区比较,鼎湖山黄果厚壳桂粗死木残体的分解速率常数K值显著高于前者。还就粗死木残体基质组成和性质、气候与环境条件、生物等因素对粗死木分解速率的影响进行了详细的讨论。

Decomposition of Cryptocarya concinna coarse woody debris (CWD) in Dinghushan

The study reported the decay constants of fallen coarse woody debris of Cryptocarya concinna in three diameters(5～10 cm,10～20 cm and 20～30 cm)in Dinghushan research station in China. For this purpose,the density loss and the C/N ratio were determined and the chronosequence method was applied with 1 to 6 years series of natural field incubations after natural disturbance. In the full range of the diameters studied,the decay constants K decreased exponentially from 0.222 5a -1 to 0.125 7a -1 with the diameter increase and the time for loss of 95% of material calculated form density loss in three diameters were 13,19 and 24 years from smaller CWD to larger ones. There was no lag time for decomposition initiation. The similar decay rate between the bark and the heartwood and the C/N ratio change indicated the single exponential model fitted the decay process of the C.concinna with accuracy. The decay constants of the C.concinna CWD appeared much greater than those of the cold temperate conifers and also higher than those of the hardwoods of the cold and warm temperate zones of the Northern Hemisphere.