马尾松人工林林窗内土壤动物作用下凋落叶C元素的动态变化

Effects of Soil Fauna on C Dynamics in Different Sized Forest Gaps in Pinus massoniana Plantation

土壤动物对凋落叶养分元素动态具有重要影响,但这种影响受控于凋落叶质量及环境条件。为了解不同大小林窗(G1:100 m^2、G2:400 m^2、G3:900 m^2、G4:1 600 m^2)内土壤动物对凋落叶中C元素季节动态的影响,采用凋落叶分解袋的方法,于凋落叶第一年分解的冬、春、夏、秋四个季节,研究了3.00和0.04 mm孔径凋落叶袋中长江上游马尾松人工林两种植物马尾松(Pinus massoniana)、樟(Cinnamomum camphora)凋落叶中的C元素动态特征。结果表明:土壤动物明显促进了2种凋落叶C的释放,且中型林窗(G3:900 m^2)内凋落叶C损失率更高;不同季节土壤动物对凋落叶中C释放量的影响存在显著差异:土壤动物对凋落叶C释放的影响主要在春季和夏季,秋、冬两季部分林窗出现C富集现象;相对于针叶植物凋落叶,土壤动物对阔叶植物凋落叶中C元素动态的影响更为显著。这些结果说明中型林窗内土壤动物对凋落叶C释放有显著影响,在马尾松低效林改造过程中,可利用中型林窗这一显著作用,引入更容易被土壤动物分解的乡土阔叶树种樟,加速马尾松人工林的物质循环。

Soil fauna has an important effect on litter nutrient release, and the effect could vary with litter types and be controlled by environmental factors such as temperature and precipitation. We to characterized the effect of soil fauna on C dynamics in different sized forest gaps （ G1 ： 100 m2, G2 ： 400 m2, G3 ： 900 m2, G4 ： 1 600 m2 ） during litter decomposition of a Pinus massoniana plantation in a hilly area of the upper reaches of Yangtze River. A field litterbag experiment was conducted in P. massoniana plantation of Sichuan, China, from January 2014 to November 2014. Samples of air-dried leaf litter for P. massoniana （Pro） and Cinnamomum camphora （Cc） were placed in nylon litterbags （20 cmx 20 cm, 10 g per bag） of two different mesh sizes （3.00 and 0. 04 ram）. The amount of C released were investigated in different sized forest gaps during the first year of decomposition, i.e. , Spring, Summer, Autumn and Winter. There was a significant difference in the amount of litter C released through soil fauna among different sized gaps ： medium sized gap （ G3 ： 900 m2 ） promoted the C release of Cc and Pm. The content of C displayed a declining trend in Spring and Summer, but with an obvious enrichment process in Winter and Autumn. Soil fauna imposed a positive effect on C release, the contribution of soil fauna to the C loss rate displayed as Cc 〉 Pro. Based on the above results, soil fauna imposed a positive effect on C release in P. massoniana plantation. When we reconstruct the low-function forest, we can take advantage of medium sized gap and introduce native broad-leaf tree species Cc which is easier to be decomposed by soil fauna to accelerate nutrient cycling and maintains the soil fertility of P. massoniana plantation.