Liu Wenjing, Graham Emily B, Zhong Linghao, Zhang Jianwei, Li Shijie, Lin Xiangui, Feng Youzhi
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.
The College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
Front Microbiol. 2020 May 15;11:873. doi: 10.3389/fmicb.2020.00873. eCollection 2020.
Revealing temporal patterns of community assembly processes is important for understanding how microorganisms underlie the sustainability of agroecosystem. The ancient terraced rice paddies at Longji provide an ideal platform to study temporal dynamics of agroecosystem sustainability due to their chronosequential records of soil physicochemistry and well-archived microbial information along 630-year rice cultivation. We used statistical null models to evaluate microbial assembly processes along the soil chronosequences of Longji rice paddies through time. Stochastic and deterministic assembly processes jointly governed microbial community composition within successional eras (less than 250 years), and within-era determinism was mainly driven by soil fertility and redox conditions alone or in combination. Conversely, across successional eras (i.e., over 300 years), stochasticity linearly increased with increasing duration between eras and was eventually predominant for the whole 630 years. We suggest that the impact of stochasticity vs. determinism on assembly is timescale-dependent, and we propose that the importance of stochastic assembly of microbial community at longer timescales is due to the gradual changes in soil properties under long-term rice cultivation, which in turn contribute to the sustainability of paddy ecosystem by maintaining a diverse community of microorganisms with multi-functional traits. In total, our results indicate that knowledge on the timescales at which assembly processes govern microbial community composition is key to understanding the ecological mechanisms generating agroecosystem sustainability.
揭示群落组装过程的时间模式对于理解微生物如何支撑农业生态系统的可持续性至关重要。龙脊古梯田因其630年水稻种植过程中土壤物理化学性质的时间序列记录以及保存完好的微生物信息，为研究农业生态系统可持续性的时间动态提供了一个理想平台。我们使用统计零模型来评估龙脊稻田土壤时间序列上微生物组装过程随时间的变化。随机和确定性组装过程共同支配着演替时期（少于250年）内的微生物群落组成，而时期内的确定性主要单独或共同由土壤肥力和氧化还原条件驱动。相反，在连续的演替时期（即超过300年），随机性随着不同时期之间持续时间的增加而线性增加，并且在整个630年中最终占据主导地位。我们认为，随机性与确定性对组装的影响取决于时间尺度，并且我们提出在较长时间尺度上微生物群落随机组装的重要性是由于长期水稻种植下土壤性质的逐渐变化，这反过来通过维持具有多功能特征的多样化微生物群落而有助于稻田生态系统的可持续性。总的来说，我们的结果表明，了解组装过程控制微生物群落组成的时间尺度是理解产生农业生态系统可持续性的生态机制的关键。
