Liang Yuting, Wu Liyou, Clark Ian M, Xue Kai, Yang Yunfeng, Van Nostrand Joy D, Deng Ye, He Zhili, McGrath Steve, Storkey Jonathan, Hirsch Penny R, Sun Bo, Zhou Jizhong
Institute for Environmental Genomics and Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Rothamsted Research, Harpenden, Herts, United Kingdom.
mBio. 2015 Apr 7;6(2):e00240-15. doi: 10.1128/mBio.00240-15.
Spatial scaling is a critical issue in ecology, but how anthropogenic activities like fertilization affect spatial scaling is poorly understood, especially for microbial communities. Here, we determined the effects of long-term fertilization on the spatial scaling of microbial functional diversity and its relationships to plant diversity in the 150-year-old Park Grass Experiment, the oldest continuous grassland experiment in the world. Nested samples were taken from plots with contrasting inorganic fertilization regimes, and community DNAs were analyzed using the GeoChip-based functional gene array. The slopes of microbial gene-area relationships (GARs) and plant species-area relationships (SARs) were estimated in a plot receiving nitrogen (N), phosphorus (P), and potassium (K) and a control plot without fertilization. Our results indicated that long-term inorganic fertilization significantly increased both microbial GARs and plant SARs. Microbial spatial turnover rates (i.e., z values) were less than 0.1 and were significantly higher in the fertilized plot (0.0583) than in the control plot (0.0449) (P < 0.0001). The z values also varied significantly with different functional genes involved in carbon (C), N, P, and sulfur (S) cycling and with various phylogenetic groups (archaea, bacteria, and fungi). Similarly, the plant SARs increased significantly (P < 0.0001), from 0.225 in the control plot to 0.419 in the fertilized plot. Soil fertilization, plant diversity, and spatial distance had roughly equal contributions in shaping the microbial functional community structure, while soil geochemical variables contributed less. These results indicated that long-term agricultural practice could alter the spatial scaling of microbial biodiversity.
Determining the spatial scaling of microbial biodiversity and its response to human activities is important but challenging in microbial ecology. Most studies to date are based on different sites that may not be truly comparable or on short-term perturbations, and hence, the results observed could represent transient responses. This study examined the spatial patterns of microbial communities in response to different fertilization regimes at the Rothamsted Research Experimental Station, which has become an invaluable resource for ecologists, environmentalists, and soil scientists. The current study is the first showing that long-term fertilization has dramatic impacts on the spatial scaling of microbial communities. By identifying the spatial patterns in response to long-term fertilization and their underlying mechanisms, this study makes fundamental contributions to predictive understanding of microbial biogeography.
空间尺度是生态学中的一个关键问题，但诸如施肥等人为活动如何影响空间尺度却鲜为人知，尤其是对于微生物群落而言。在此，我们在拥有150年历史的帕克草地试验（世界上最古老的连续草地试验）中，确定了长期施肥对微生物功能多样性空间尺度的影响及其与植物多样性的关系。从具有不同无机施肥方案的地块中采集嵌套样本，并使用基于GeoChip的功能基因阵列分析群落DNA。在一块施氮（N）、磷（P）和钾（K）的地块以及一块未施肥的对照地块中，估计微生物基因 - 面积关系（GARs）和植物物种 - 面积关系（SARs）的斜率。我们的结果表明，长期无机施肥显著增加了微生物GARs和植物SARs。微生物空间周转率（即z值）小于0.1，且在施肥地块（0.0583）中显著高于对照地块（0.0449）（P < 0.0001）。z值也因参与碳（C）、氮（N）、磷（P）和硫（S）循环的不同功能基因以及不同的系统发育类群（古菌、细菌和真菌）而有显著差异。同样，植物SARs显著增加（P < 0.0001），从对照地块的0.225增加到施肥地块的0.419。土壤施肥、植物多样性和空间距离在塑造微生物功能群落结构方面的贡献大致相等，而土壤地球化学变量的贡献较小。这些结果表明，长期农业实践可能会改变微生物生物多样性的空间尺度。
确定微生物生物多样性的空间尺度及其对人类活动的响应在微生物生态学中很重要但具有挑战性。迄今为止，大多数研究基于可能并非真正可比的不同地点或短期扰动，因此，观察到的结果可能代表瞬时响应。本研究在罗瑟拉姆斯特德研究实验站研究了微生物群落对不同施肥方案的空间模式，该实验站已成为生态学家、环境学家和土壤科学家的宝贵资源。当前研究首次表明长期施肥对微生物群落的空间尺度有显著影响。通过识别对长期施肥的空间模式及其潜在机制，本研究为预测性理解微生物生物地理学做出了基础性贡献。
