Enhanced UV radiation levels and decreased rainfall in Mediterranean terrestrial ecosystems due to climate change might impact soil bacterial communities, significantly altering their structure and affecting biogeochemical cycles. The aim of this study was to evaluate the effect of UV-B and UV-A radiation on soil bacterial richness, abundance and community composition in a Typic Dystroxerept of Mediterranean shrubland and to determine whether these effects depend on reduced rainfall and/or soil physicochemical properties. Soils were subjected to long-term UV conditions: UV-A + UV-B exclusion (UV0 plots), UV-B exclusion (UVA plots), or ambient UV-A + UV-B exposure (UVAB plots), and combined with two rainfall regimes, natural (NR) and reduced (RR) rainfall. Barcoded amplicon 16S rRNA gene sequencing was used to analyse changes in microbial diversity. UV radiation did not affect bacterial richness and diversity indexes and only minor differences in species composition were observed. Unidentified species of the Longimicrobiaceae appeared to be in greater abundance in the UV0 plots than in the UVA and UVAB, especially under natural rainfall, whereas members of the Pyrinomonadaceae and Ktedonobacteraceae were more abundant in UVAB. Rainfall reduction resulted in lower bacterial abundance but higher diversity (Shannon–Weiner and InvSimpson indexes) under UV exclusion. The results pointed to a combined response of soil bacterial communities to UV radiation and rainfall treatments. However, the small changes observed suggest a high resilience of the Mediterranean shrubland soil microbiome to the projected changes in UV and rainfall conditions.

中文翻译：

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诱导干旱和操纵紫外线辐射后地中海土壤中微生物群落的恢复力

由于气候变化，地中海陆地生态系统中紫外线辐射水平增强和降雨减少可能会影响土壤细菌群落，显着改变其结构并影响生物地球化学循环。本研究的目的是评估 UV-B 和 UV-A 辐射对地中海灌木丛典型 Dystroxerept 土壤细菌丰富度、丰度和群落组成的影响，并确定这些影响是否取决于降雨减少和/或土壤物理化学特性。土壤经受长期紫外线条件：UV-A + UV-B 排斥（UV0 图）、UV-B 排斥（UVA 图）或环境 UV-A + UV-B 暴露（UVAB 图），并结合两种降雨方式，自然（NR）和减少（RR）降雨。条形码扩增子 16S rRNA 基因测序用于分析微生物多样性的变化。紫外线辐射不影响细菌丰富度和多样性指数，仅观察到物种组成的微小差异。不明物种在UV0图中，长微生物科似乎比在 UVA 和 UVAB 中的丰度更高，特别是在自然降雨下，而在 UVAB 中Pyrinomonadaceae和Ktedonobacteraceae的成员更丰富。在紫外线排斥下，降雨减少导致细菌丰度降低，但多样性（香农-韦纳和 InvSimpson 指数）增加。结果表明土壤细菌群落对紫外线辐射和降雨处理的综合反应。然而，观察到的微小变化表明地中海灌丛土壤微生物组对紫外线和降雨条件的预计变化具有很高的弹性。