人工油松林不同生长阶段深层土壤有机碳和活性碳的差异及其影响因素

研究深层土壤碳库动态对了解陆地生态系统深层碳汇潜力、应对全球CO₂升高具有重要意义。论文以黄土丘陵区人工油松林为研究对象,以撂荒地为参照,分析了不同生长阶段的人工油松林地0~200 cm土层土壤有机碳（soil organic carbon,SOC）和活性有机碳（readily oxidizable carbon,ROC）动态变化特征及其影响因素。结果表明：在0~200 cm剖面上,不同生长阶段油松林SOC含量及储量较撂荒地显著提高。浅层（0~100 cm）SOC平均含量,成熟林为撂荒地的2.03倍,提高最大;其次是中龄林,为1.85倍;最后是幼龄林,为1.59倍。深层（100~200 cm）SOC平均含量,幼龄林、中龄林和成熟林分别较撂荒地提高了1.43、1.38和1.36倍。各生长阶段油松林浅层和深层SOC储量分别占0~200 cm SOC储量的61.0%~69.8%和30.2%~39.0%,不同生长阶段间浅层SOC储量差异显著,但深层SOC储量差异不大。浅层ROC储量,幼龄林、中龄林和成熟林依次提高了54.8%、82.0%和91.6%;深层ROC储量依次提高了32.4%、40.9%和58.1%,且深层储量占0~200 cm土层的31.2%~33.3%。不仅浅层SOC和ROC含量受多个因素的影响,而且深层ROC含量也与油松高度、根系生物量以及枯落物厚度、干重呈极显著正相关。因此,人工林建设不仅显著提高浅层SOC和ROC含量,而且对深层土壤的固碳能力有一定改善。

Changes of Organic Carbon and Readily Oxidizable Carbon in Deep Soil at Different Developmental Stages of Artificial Pinus tabulaeformis Plantation and the Impact Factors

It is not clear how plantation affect the soil organic carbon (SOC) in deep soil for terrestrial ecosystem. Based on space for time method, we studied the effect of Pinus tabulaeformis plantations at three developmental stages (young forest, middle age forest and mature forest) on the soil organic carbon (SOC) and soil readily oxidizable carbon (ROC) in 0-200 cm soil profile. The results showed that SOC content and storage significantly increased in soils with different developmental stages of Pinus tabulaeformis plantation compared with abandoned cropland in 0-200 cm profile. In the 0-100 cm soil layer, average SOC content of mature forest, middle age forest and young forest were 2.03, 1.85 and 1.59 times more than that in abandoned cropland, respectively. SOC storage in shallow and deep soil layers contributed 61.0%-69.8% and 30.2%-39.0% to total SOC storage in the whole profile (0-200 cm) at all of the investigated developmental stages. SOC storage in shallow soil layer varied significantly among different developmental stages, however, no obvious difference of SOC storage in deep soil layer was observed at all developmental stages. Compared to that in abandoned cropland, the ROC storage in soils of young forest, middle age forest and mature forest increased 54.8%, 82.0% and 91.6% in shallow soil layer and 32.4%, 40.9% and 58.1% in deep soil layer, respectively. ROC storage in deep soil layer contributed 31.2%-33.3% to total ROC storage in the whole profile (0-200 cm) at all developmental stages. SOC and ROC content in shallow soil layer were influenced by a number of factors, furthermore, ROC content in deep soil showed significant correlations with the plant height, root biomass, litter thickness and litter biomass. In conclusion, construction of artificial forest may significantly improve the soil carbon pool in both shallow and deep soil profiles.