不同耕作方式下黑土微生物群落稳定性的研究–以干湿交替为干扰

Long-term conventional tillage has induced severe soil degradation in agro-ecosystems of northeastern China. For this reason, alternative tillage practices were introduced. The effect of tillage practices on soil microbial properties has been well studied with respect to microbial biomass, activity, and community structure. However, less is known about the effects on stability of microbial communities after environmental disturbance. Changes in stability of microbial communities will influence the ability of soil to balance and recover its functions after environmental disturbance, which is critical to sustainable agriculture. In this study, differently-tilled Mollisols were subjected to different frequency and intensity of dry-wet cycles, and changes in the structure and functions of soil microbial community after disturbance were monitored. The objectives of this study were to examine the resistance and resilience of soil microbial communities under different tillage practices, to identify the main factors that influence the stability of soil microbial communities, to analyze the relationship between soil microbial community structure and functional stability, and finally to compare the differences in microbial stability between tillage practices. This study will help us to understand the effect of tillage practices on the stability of soil microbial communities and underlying mechanism, and to choose tillage practices for sustainable agriculture in northeastern China.

长期传统耕作导致东北农田黑土退化严重，为此其他耕作方式被引入生产实践。目前对不同耕作方式下土壤微生物的研究主要集中在微生物数量、活性及群落组成方面，而对环境干扰后土壤微生物群落稳定性的认识还非常有限。微生物群落稳定性直接影响土壤对环境干扰的自我平衡和恢复能力，这对土壤的可持续利用至关重要。本项目以东北农田黑土为供试对象，以不同频率和强度的干湿交替为干扰，系统研究不同耕作方式下土壤微生物群落结构和功能对干湿交替的响应规律，定量化评价不同耕作方式下微生物群落对干扰的抵抗力和恢复力，深入分析影响微生物群落稳定性的主要因素，探讨不同耕作方式下土壤微生物群落结构和功能稳定性之间的内在联系，最终阐明不同耕作方式下土壤微生物群落稳定性的差异。本研究不仅有助于深入理解不同耕作方式下土壤生态系统稳定性的微生物作用机制，而且对东北黑土区选择合理的耕作方式及土壤生态系统的可持续管理具有重要指导意义。

耕作方式影响土壤理化性质和微生物群落结构，进而可能影响土壤生态功能对环境干扰的抵抗和恢复能力。目前关于环境干扰后土壤微生物群落和功能稳定性的认识还非常有限。本项目以东北农田黑土为供试对象，以不同频率和强度的干湿交替为干扰，研究了不同耕作方式下土壤微生物群落结构和功能对干湿交替的响应规律，评价了不同耕作方式下微生物群落结构和功能对干扰的抵抗力和恢复力，探讨了不同耕作方式下土壤微生物群落结构和功能稳定性之间的内在联系。结果发现不同耕作方式下土壤微生物群落结构对干湿交替干扰的响应不同：在免耕土壤中，1次干旱-浇水处理不影响土壤微生物群落结构，而3次干旱-浇水显著改变了微生物群落结构；在垄作土壤中，不论是1次干旱-浇水干扰，还是3次干旱-浇水循环，均显著改变了土壤微生物的群落结构。研究还发现干湿交替干扰后垄作土壤中的二氧化碳和氧化亚氮气体排放速率未能恢复到对照处理，同时其纤维素酶活性完全丧失。研究结果初步表明免耕土壤对干旱-浇水干扰的恢复力显著高于垄作土壤，暗示在未来气候变化，尤其是干旱扰动不是太极端时，免耕土壤中的生态功能能够正常发挥，而垄作土壤中的部分功能可能完全丧失。本研究为预测气候变化对土壤生态功能的影响和制定土壤生态系统可持续管理政策具有重要的指导意义。