The differences of artificial measures, such as logging residue management, between assisted natural regeneration and afforestation may change the content and structure of soil dissolved organic carbon (DOC) and affect forest carbon cycle. In this study, we investigated the effects of managements on the content and spectral characteristics of DOC in a subtropical forest, which contained the forest of assisted natural regeneration (Ⅱ), and the plantation (Ⅲ), both were converted from mature secondary forests (Ⅰ). Results showed that DOC content in the 0-10 cm soil layer was significantly decreased by 21% and 50% in Ⅱ and Ⅲ, respectively, compared with that in Ⅰ. The DOC/SOC (soil organic carbon) ratios of 0-10 cm and 10-20 cm soil layers were significantly decreased by 27% and 43% after the conversion, respectively. In the 0-10 cm soil layer, the aromatic index and humification index of DOC in Ⅱ were significantly higher than that in Ⅲ. The infrared absorption ratio of soil DOC in the range of 3700-3000 cm-1, 1650-1620 cm-1, 1160-1000 cm-1, and 690-530 cm-1 in Ⅱ was higher than that in Ⅲ, indicating that the DOC in Ⅱ had higher carboxylic acids and aromatic substances than Ⅲ. The fluorescence index of DOC in Ⅱ and Ⅲ ranged from 1.4 to 1.9, and the biological index of Ⅱ was significantly higher than that of Ⅲ, indicating that Ⅲ had higher protein components in DOC and being more bioavailable. Thus, the differences of the content and structure of DOC between Ⅱ and Ⅲ might cause higher soil carbon pool of Ⅱ than that of Ⅲ.
人工促进天然更新与人工造林经营方式中采伐剩余物管理等人工措施的差异,可能改变土壤可溶性有机碳(DOC)的含量和结构,影响森林碳循环。本研究利用天然次生林(对照)采伐迹地上通过人工促进天然更新林(简称人促更新林)和人工造林两种营林方式,研究经营方式对中亚热带森林土壤溶液可溶性有机碳含量和光谱特征的影响。结果表明:天然次生林转换为人促更新林和人工林后,0～10 cm土层土壤DOC含量显著降低,分别下降21%和50%;0～10 cm和10～20 cm土层土壤DOC/SOC(土壤有机碳)值也显著降低,分别达到27%和43%。在0～10 cm土层中,人促更新林土壤DOC芳香化指数和腐殖化指数显著高于人工林,人促更新林土壤DOC在3700～3000、1650～1620、1160～1000、690～530 cm-1范围内的红外吸收比例较人工林高,表明人促更新林土壤DOC的羧酸类物质、芳香化物质丰富;人促更新林和人工林土壤DOC的荧光指数均为1.4～1.9,且人促更新林自生源指数显著高于人工林,说明人工林土壤DOC类蛋白组分贡献大,容易被微生物分解利用。人促更新林与人工林土壤DOC含量和结构的差异可能是人促更新林的土壤碳库比人工林更高的原因之一。.
Keywords: aromatic index; assisted natural regeneration; dissolved organic carbon; humification index; infrared spectrum.