The spatial scale-dependency of diazotrophic and bacterial community assembly in paddy soil

Authors: GAO, QUN - Tsinghua University; YANG, YUNFENG - Tsinghua University; FENG, JIAJIE - University Of Oklahoma; TIAN, RENMAO - Oklahoma State University; GUO, XUE - Central South University; NING, DALIANG - University Of Oklahoma; Hale, Lauren; WANG, MENGMENG - Tsinghua University; CHENG, JINGMIN - Tsinghua University; WU, LINWEI - University Of Oklahoma; ZHAO, MENGXIN - Chinese Academy Of Sciences; ZHAO, JIANSHU - Tsinghua University; WU, LIYOU - University Of Oklahoma; QIN, YUJIA - University Of Oklahoma; QI, QI - Tsinghua University; LIANG, YUTING - Chinese Academy Of Agricultural Sciences; SUN, BO - Chinese Academy Of Sciences; CHU, HAIYAN - Chinese Academy Of Sciences; ZHOU, JIZHONG - University Of Oklahoma

Submitted to: Global Ecology and Biogeography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2019
Publication Date: 5/13/2019
Citation: Gao, Q., Yang, Y., Feng, J., Tian, R., Guo, X., Ning, D., Hale, L.E., Wang, M., Cheng, J., Wu, L., Zhao, M., Zhao, J., Wu, L., Qin, Y., Qi, Q., Liang, Y., Sun, B., Chu, H., Zhou, J. 2019. The spatial scale-dependency of diazotrophic and bacterial community assembly in paddy soil. Global Ecology and Biogeorgraphy. 28(8):1093-1105. https://doi.org/10.1111/geb.12917.
DOI: https://doi.org/10.1111/geb.12917

Interpretive Summary: Soil microorganisms are critical drivers of biogeochemical processes. Specifically, diazotrophic communities mediate soil nitrogen (N) in rice paddies, wherein flooding practices induce significant N losses. This research examined profiles of microbial taxa and genes involved in nitrogen fixation to evaluate how variations in genetic diversity across sampling sites (ß diversity) differed with increasing spatial scales. Overall, drivers of diazotrophic and bacterial community ß diversity, such as species associations, showed varying patterns depending on the spatial scale. These results provide insights into the spatial patterns of microbial functional ß diversity, which is crucial for predicting and elucidating ecosystem functions.

Technical Abstract: Microorganisms play essential roles mediating earth’s biogeochemical processes. Specifically, diazotrophic communities are critical drivers of soil nitrogen (N) bioavailability, especially in rice paddies, owing to significant N losses when soils are flooded. Understanding the spatial pattern of microbial functional ß diversity is crucial for predicting and elucidating ecosystem functions. This research examined whether spatial scale-dependent patterns of microbial community ß diversity vary between microbial functional groups and bacterial taxa across local to regional scales (from meters to hundreds of kilometres) in Eastern China. Two complementary statistical tools were employed to unveil biotic mechanisms (i.e., species association) underlying ß diversity variation of diazotrophic and total bacterial communities. Distance-decay slopes of both communities at the local (1 – 113 m), meso (3.4 – 39 km) and regional (103 – 668 km) scales were determined. Environmentally-constrained checkerboard score and topological features of association networks were also used as indices of species associations. Then, contributions of species associations, abiotic factors and geographic distances to explaining community ß diversity were calculated. The scale-dependent distance-decay was examined in ubiquitous (high occupancy across samples) and endemic communities of diazotrophs and bacteria. Diazotrophs displayed steeper distance-decay slopes than bacteria, suggesting the ß diversity of diazotrophic communities was more variable. The distance-decay slopes were spatial scale-dependent in both communities, owing to different contributions of geographic distance, abiotic factors and species associations at three spatial scales. Intriguingly, species association was greater and contributed more to community ß diversity than other forces at the local scale, implying species association could strongly alter community structures.