鼎湖山木荷(Schima Superba)粗死木质残体的分解研究

Decomposition of Coarse Woody Debris (CWD) of Dominate Species Schima superba in Monsoonal Evergreen Broadleaved Forest of Dinghushan Nature Reserve

以鼎湖山国家自然保护区季风常绿阔叶林优势种之一木荷的粗死木质残体为研究对象,采用目前国际较认可的腐解等级划分方法,对木荷粗死木质残体3个腐解等级(Ⅰ、Ⅱ、Ⅲ)的密度及养分含量进行测定分析。结果表明:①木荷粗死木质残体的密度随腐解等级的增加从0.58 g/cm3下降到0.16 g/cm3,分解速率常数K值为0.144 7/a,在自然状态下,木荷粗死木质残体分解95%所需时间约为21 a;②粗死木质残体C/N比值随分解的进行先降后升而N/P则相反;③K、Ca、Na、Mg离子浓度随腐解等级的增加出现不同程度的增加,但增幅不明显。研究结果旨在为系统评估粗死木质残体的分解行为在生态系统养分循环中的作用提供基础数据。

According to an international standardized definition and classification that recently adopted widely for Coarse woody debris （CWD）, CWD has been investigated in Dinghushan Nature Reserve monsoonal evergreen broadleaved forest, Guangdong Province in lower subtropical China, where permanent field plots from a 16-year （from 1992 to 2008） study of ecosystem structure and function in an old growth forest were surveyed to obtain sam- ple data on CWD volume, density, and mass of dominant species Schima superba. CWD was studied to exam nutri- ent by classifying three classes I, II, and III respectively. The results showed that ： （ 1 ） the density of Sehima su- perba CWD decreased from 0.58 g/ cm3 to 0. 16 g/ cm3 with the decay class increasing, and decay rate （K） of Sehima superba CWD in a monsoonal evergreen broadleaved forest estimated as 0. 144 7 per year. Under natural conditions, the decay time of Schima superba CWD at the loss of 95% initial mass is approximately 21a; （2） The variation responding to all the three classes I, II, and III decreased in C/N ratio from 268 to 161 then increased to 251 respectively, while N/P ratio increased from 12 to 15 then decreased to 9. （3） the concentrations of K＋ , Ca2＋ ,Na ＋ ,Mg2＋ increased with the change from one class to the succeeding class but not significantly. The goal here was to determine the decomposition rate of Schirna superba CWD; it is expect that this study will help explain the behavior CWD in nutrient cycling in forest ecosystem.