Rather than simple accumulation of individual populations, microorganisms in natural ecosystems form complex ecological networks that are critical to maintain ecosystem functions and services. Although various studies have examined the patterns of microbial community diversity and composition across spatial gradients, whether microbial co-occurrence relationships follow similar patterns remains an open question. In this study, we determined the biogeographic patterns of microbial co-occurrence networks of bacteria, fungi and nitrogen (N) fixer via analyses of high throughput amplicon sequencing data of 16S rRNA, ITS, and nifH genes from 126 forest soil samples across six forests in America. Microbial co-occurrence networks were constructed using a Random Matrix Theory based approach. Network parameters were calculated and correlated with biogeographic parameters. Gradient patterns along with biogeographic parameters were observed for network topologies. Significantly different network topologies were observed between microbial co-occurrence networks in tropical and temperate forest ecosystems. Among various biogeographic parameters potentially related with network topology indices, temperature seemed to be the strongest one. These results suggest that biogeographic variables like temperature not only mediate microbial community diversity and composition, but also the co-occurrence ecological networks among microbial species.

自然生态系统中的微生物不是简单的个体种群积累，而是形成了复杂的生态网络，这对于维持生态系统的功能和服务至关重要。尽管各种研究已经研究了跨空间梯度的微生物群落多样性和组成模式，但是微生物共生关系是否遵循相似的模式仍然是一个悬而未决的问题。在这项研究中，我们通过分析16S rRNA，ITS和nifH的高通量扩增子测序数据，确定了细菌，真菌和氮（N）固定剂的微生物共生网络的生物地理模式。来自美国6个森林的126个森林土壤样本的基因。使用基于随机矩阵理论的方法构建微生物共生网络。计算网络参数并将其与生物地理参数相关联。观察到网络拓扑的梯度模式以及生物地理参数。在热带和温带森林生态系统中，微生物共生网络之间观察到明显不同的网络拓扑。在可能与网络拓扑指数相关的各种生物地理参数中，温度似乎是最强的。这些结果表明，温度等生物地理变量不仅可以调节微生物群落的多样性和组成，而且可以调节微生物物种之间的共生生态网络。