Li Na, Wang Baorong, Huang Yimei, Huang Qian, Jiao Feng, An Shaoshan
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Science and Ministry of Water Resources, Yangling 712100, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2022 Sep 10;838(Pt 2):156191. doi: 10.1016/j.scitotenv.2022.156191. Epub 2022 May 23.
The impact of the long-term uneven precipitation distribution model on the diversity and community composition of soil C-fixing microorganisms in arid and semiarid grasslands remains unclear. In 2015, we randomly set up five experimental plots with precipitation gradients on the natural restoration grassland of the Loess Plateau (natural precipitation, NP; ± 40% natural precipitation: decreased precipitation (DP), DP40; increased precipitation (IP), IP40; ± 80% natural precipitation: DP80; IP80). In the third and fifth years after the experimental layout (spanned two years), we explored the cbbL-genes, which are functional genes in the Calvin cycle, harboring microbial diversity and community composition under different precipitation treatments. The results showed that the increase in mean annual precipitation significantly changed the cbbL-harboring microbial alpha diversity, especially when controlling for 40% natural precipitation. The response of the dominant microbial communities to interannual increased precipitation variation shifted from Gammaproteobacteria (Bradyrhizobium) to Betaproteobacteria (Variovorax). The structural equation model showed that precipitation directly affected the cbbL-harboring microbial diversity and community composition and indirectly by affecting soil NO (mg N kg ), soil organic matter, dissolved organic N content, and above- and underground biomass. In conclusion, studying how cbbL-harboring microbial diversity and community composition respond to uneven precipitation variability provides new insights into the ecological processes of C-fixing microbes in semi-arid naturally-restored grasslands dominated by the Calvin cycle.
长期不均匀降水分布模式对干旱和半干旱草原土壤固碳微生物多样性及群落组成的影响尚不清楚。2015年，我们在黄土高原天然恢复草地（自然降水，NP；±40%自然降水：降水减少（DP），DP40；降水增加（IP），IP40；±80%自然降水：DP80；IP80）上随机设置了5个具有降水梯度的实验小区。在实验布置后的第三年和第五年（跨越两年），我们探究了卡尔文循环中的功能基因cbbL基因，其蕴含不同降水处理下的微生物多样性和群落组成。结果表明，年平均降水量的增加显著改变了携带cbbL基因的微生物α多样性，尤其是在控制40%自然降水时。优势微生物群落对年际降水增加变化的响应从γ-变形菌纲（慢生根瘤菌属）转变为β-变形菌纲（贪噬菌属）。结构方程模型表明，降水直接影响携带cbbL基因的微生物多样性和群落组成，并通过影响土壤NO（mg N kg）、土壤有机质、溶解有机氮含量以及地上和地下生物量间接产生影响。总之，研究携带cbbL基因的微生物多样性和群落组成如何响应不均匀降水变异性，为以卡尔文循环为主导的半干旱天然恢复草地中固碳微生物的生态过程提供了新见解。
