Liu Zeng-wen, Duan Er-jun, Pan Kai-wen, Zhang Li-ping, Du Hong-xia
College of Resources Environment, Northwest A & F University, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2009 Jan;20(1):1-6.
With the planted forest ecosystems of Cercidiphyllum japonicum, Betula utilis, Pinus yunnansinsis, and Picea asperata in subalpine area of west Sichuan as test objects, their total biomass and the C and N contents in soils and tree organs were determined. The results showed that the allocation of C in tree organs had less correlation with the age of the organs, while that of N and C/N ratio had closer relationship with the age. The N content in young organs was higher than that in aged ones, whereas the C/N ratio was higher in aged organs than in young organs, and higher in the leaf litters of needle-leaved forests than in those of broad-leaved forests. There was an obvious enrichment of C and N in the topsoil of test forests. The accumulated amounts of C and N in the whole planted forest ecosystem, including tree, litter, and 0-40 cm soil layer, were 176.75-228.05 t x hm(-2) and 11.06-16.54 t x hm(-2), respectively, and the nutrients allocation ratio between soil-litter and tree was (1.9-3.3):1 for C and (15.6-41.5):1 for N. Needle-leaved forests functioned as a stronger "C-sink" than broad-leaved forests. The decomposition rate of the leaf litters in needle-leaved forests was larger than that in broad-leaved forests, with the turnover rate being 2.2-3.7 years and 3.9-4.2 years, respectively. During the decomposition of leaf litter, the C in all of the four forests released at super-speed, with the turnover rate being 1.9-3.4 years. As for N, it also released at super-speed in C. japonicum and B. utilis forests, with the turnover rate being 1.9-3.2 years, but released at low speed in P. yunnansinsis and P. asperata forests, with the turnover rate being 6.7-8.5 years.
以川西亚高山地区的连香树、糙皮桦、云南松和云杉人工林生态系统为试验对象，测定了其总生物量以及土壤和树木器官中的碳、氮含量。结果表明，树木器官中碳的分配与器官年龄的相关性较小，而氮和碳氮比与年龄的关系更为密切。幼嫩器官中的氮含量高于成熟器官，而成熟器官中的碳氮比高于幼嫩器官，针叶林凋落物中的碳氮比高于阔叶林。试验林表层土壤中碳和氮有明显富集。整个人工林生态系统（包括树木、凋落物和0至40厘米土层）中碳和氮的累积量分别为176.75至228.05吨·公顷⁻²和11.06至16.54吨·公顷⁻²，土壤-凋落物与树木之间的养分分配比碳为(1.9至3.3):1，氮为(15.6至41.5):1。针叶林作为“碳汇”的功能比阔叶林更强。针叶林凋落物的分解速率大于阔叶林，周转期分别为2.2至3.7年和3.9至4.2年。在凋落物分解过程中，四种森林中的碳均以超速释放，周转期为1.9至3.4年。至于氮，在连香树和糙皮桦林中也以超速释放，周转期为1.9至3.2年，但在云南松和云杉林中释放速度较慢，周转期为6.7至8.5年。
