水旱轮作对土壤微生物群落构建过程的影响机制

为探究稻田生态系统微生物学机制,采集水旱轮作稻田土壤,并以相同土壤母质下长期淹水的藕田土壤以及旱作的果树土壤为对照,研究了稻田生态系统细菌群落结构以及基于零模型的群落构建机制。结果表明:旱作和水旱轮作两个生态系统,由于频繁耕作以及施肥管理等农业措施形成特定的生态位格局,确定性过程主导群落构建。旱作生态系统下确定性过程占78.6%,随机性过程占10.7%;相对于旱作,由于水旱轮作的淹水条件,土壤肥力积累,水体连通性较好等特性导致内部环境变化缓和,其随机性过程(39.3%)影响增加,确定性过程(50.0%)下降;同理,长期淹水的水生生态系统中随机性群落构建(50.0%)成为主导过程。群落构建影响细菌群落结构和功能,因此随机性生态过程的增强进一步增加了细菌多样性以及物种生态网络的交互度和稳定性,增强了微生物抵抗外部环境扰动的能力,该过程有助于维持农田生态系统功能的稳定性和可持续性。

Study on Community Assembly Processes Under Paddy-upland Rotation

To understand paddy-upland rotation ecosystem microbial mechanisms, the community composition and assembly processes in a paddy-upland rotation ecosystem were investigated. In addition, the samples collected from long-term flooded lotus field ecosystem and fruit-planted upland ecosystem with the same parent material were also evaluated as the control. Results showed that due to the particular niche pattern driven by frequent farming activities and fertilization management, deterministic processes dominated microbial community assembly in both upland and paddy-upland ecosystems. In upland, the deterministic processes were up to 78.6%, while stochastic processes were 10.7%. With the intermittent flooding, paddy-upland ecosystem undergoes a relatively high soil fertility accumulation and favorable hydrologic connectivity, which formed a gradual-changed inner condition. Compared to upland ecosystem, the stochastic processes (39.3%) increased in paddy-upland ecosystem. In the same way, the stochastic processes (50.0%) dominated community assembly in long-term flooded ecosystem. In total, microbial assembly processes exert great influences on community composition and functions, the increased stochastic processes favor the microbial diversity and the interactions among microbes, enhance community resistance towards disturbance, which in turn benefit the stability and sustainability of agroecosystem functions.