Supported by the National Natural Science Foundation of China (Nos. 31600378 and U20A2008) and the Fundamental Research Funds of the Central Universities of Southwest Minzu University of China (Nos.2022NYXXS045 and ZYN2022052)
草地灌丛化过程中植被优势群落类型的转变会通过凋落物及根系分泌物的数量和性质差异影响土壤有机碳（SOC）组分。为探索高寒草地土壤不同活性有机碳组分对灌木侵入的响应，本研究采用Stewart物理-化学联合分组方法，将青藏高原东缘四种典型灌丛化草地以及未灌丛化草地土壤有机碳分为游离态活性有机碳（Nonprotected organic carbon，Non-C）、物理保护态有机碳（Physically-protected organic carbon，Phy-C）、化学保护态有机碳（Chemically-protected organic carbon，Che-C）和生物化学保护态有机碳（Biochemically-protected organic carbon，Bio-C），分析不同活性有机碳组分含量变化及其影响因素。结果表明：（1）灌木侵入对高寒草地表层土壤（0～10 cm）SOC含量影响不显著（P>0.05），但不同活性有机碳组分含量有所分异。高山绣线菊（Spiraea alpina）和窄叶鲜卑花（Sibiraea angustata）灌木侵入降低了土壤Non-C和Bio-C组分（P<0.05）；金露梅（Potentilla fruticosa）灌木侵入降低了土壤Non-C组分（P<0.05）；小叶锦鸡儿（Caragana microphylla）灌木侵入降低了土壤Phy-C和Che-C组分（P<0.05），而提高了土壤Bio-C组分含量（P<0.05）。（2）未灌丛化草地和灌丛化样地土壤均以Non-C组分为主，其次是稳定态有机碳库（Che-C和Bio-C），而Phy-C占比最少。（3）土壤黏粒和全氮是影响高寒灌丛化草地土壤不同活性有机碳组分的主要因素，解释度共达51.2%。高寒草地灌木侵入过程中，灌木种类对不同活性土壤有机碳组分含量影响不一致，灌丛化草地和未灌丛化草地土壤表层均以Non-C为主，因此在外界扰动的情况下，该地区的有机碳库可能成为碳源。
【Objective】Changes in the dominant vegetation community will inevitably affect soil organic carbon (SOC) by altering the quantity of litter and root exudates during shrub encroachment. Thus, this study aimed to explore the response of different active organic carbon fractions in alpine grassland soils to invasion by different shrub species.【Method】Physicochemical fractionation method was used to divide soil organic carbon into non-protected carbon, physically-protected carbon, chemically-protected carbon and biochemically-protected carbon. It was analysed the contents of various organic carbon fractions and factors influencing their contents among four typical shrub-grassland and unshrub-encroached grassland on the east edge of Qinghai-Tibetan Plateau.【Result】The results showed that (1) Shrub encroachment has no significant effect on the SOC content of the surface soil(0-10 cm)in alpine grassland (P>0.05), but the content of organic carbon components was different. After Spiraea alpina and Sibiraea angustata shrubs encroached the grassland, the non-protected organic carbon and biochemically-protected organic carbon contents were significantly decreased (P<0.05) while the non-protected organic carbon content significantly decreased when Potentilla fruticose encroached the grassland. Also, the contents of physically-protected and chemically-protected organic carbon decreased significantly in Caragana microphylla encroached grassland (P<0.05), while the biochemically-protected organic carbon increased significantly (P<0.05). (2) SOC in both grassland and shrub patches soil were dominated by non-protected carbon pool, followed by resistant carbon pool (chemically-protected organic carbon and biochemically-protected organic carbon), while physically-protected organic carbon pool accounted for the least. (3) The contents of soil clay and total nitrogen were the main factors affecting the organic carbon fractions in alpine shrub-encroached grassland, with an explanation degree of 51.2%. 【Conclusion】The invasion of different shrub species had inconsistent effects on the content of different reactive organic carbon fractions. The soils of both unshrub grassland and shrub sample sites on the Tibetan Plateau were dominated by non-protected carbon. Thus, in the presence of external disturbances, the organic carbon pool in the area may become a source of carbon.
张东,刘金秋,马文明,王长庭,邓增卓玛,张婷.灌丛化对高寒草地土壤有机碳组分的分异研究[J].土壤学报,2023,60(6):1812-1823. DOI:10.11766/trxb202203220004 ZHANG Dong, LIU Jinqiu, MA Wenming, WANG Changting, DENGZENG Zhuoma, ZHANG Ting. Effects of Shrub Encroachment on Soil Organic Carbon Components in Qinghai-Tibetan Alpine Grassland[J]. Acta Pedologica Sinica,2023,60(6):1812-1823.复制