Background and aims

Both drought and vegetation restoration can have dramatic effects on plant community composition, but how they influence soil microbial community diversity, structure, and co-occurrence networks remain less well known.

Methods

To better understand the regulatory mechanisms of drought and vegetation restoration on soil microorganisms, we planted 12 native species in precipitation manipulation experimental plots in an invaded coastal grassland in California, USA. We measured soil bacterial and fungal community composition by amplicon sequencing, and quantified plant species richness and coverage in the third experimental year.

Results

Our results showed that drought significantly altered soil bacterial diversity and composition; however, neither drought nor vegetation restoration had significant effects on fungal diversity and composition. The control plots had the most cooperative interactions (greatest number of correlations) among bacterial and/or fungal species, while drought plots yielded the most complex co-occurrence network with the highest modularity and clustering coefficient. Structural equation modeling revealed that plant species richness, net gains, and soil moisture played dominant roles in shaping bacterial community structure. Drought and bacterial community structure directly affected fungal community structure. Plant dominant species cover, common species cover, and bacterial diversity were the key drivers in regulating the microbial co-occurrence network complex.

Conclusion

We conclude that soil bacterial and fungal communities differ in their responses to abiotic and biotic environmental changes, which may weaken the interspecies interactions among soil microorganisms.

中文翻译：

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干旱和植被恢复导致加州沿海草原土壤微生物多样性和共生网络的变化

背景和目标

干旱和植被恢复都会对植物群落组成产生巨大影响，但它们如何影响土壤微生物群落多样性、结构和共生网络仍然鲜为人知。

方法

为了更好地了解干旱和植被恢复对土壤微生物的调节机制，我们在美国加利福尼亚州一片被入侵的沿海草原的降水操纵实验田中种植了 12 个本地物种。我们通过扩增子测序测量了土壤细菌和真菌群落组成，并量化了第三个实验年的植物物种丰富度和覆盖度。

结果

我们的结果表明，干旱显着改变了土壤细菌的多样性和组成；然而，干旱和植被恢复都没有对真菌多样性和组成产生重大影响。对照地块在细菌和/或真菌物种之间具有最合作的相互作用（最多数量的相关性），而干旱地块产生了最复杂的共现网络，具有最高的模块性和聚类系数。结构方程模型表明，植物物种丰富度、净增益和土壤湿度在塑造细菌群落结构中起着主导作用。干旱和细菌群落结构直接影响真菌群落结构。植物优势物种覆盖、常见物种覆盖和细菌多样性是调节微生物共生网络复合体的关键驱动因素。

结论

我们的结论是，土壤细菌和真菌群落对非生物和生物环境变化的反应不同，这可能削弱土壤微生物之间的种间相互作用。