Global projections of the soil microbiome in the Anthropocene

Soil microbes are essential for maintaining life-supporting ecosystem
services, but projections of how these microbes will be affected by global
change scenarios are lacking. Therefore, we aim to provide projections of
future soil microbial distribution using multiple global change scenarios. We used a global database of soil microbial communities across six
continents to estimate past and future trends of the soil microbiome. To do so,
we used structural equation models to include the direct and indirect effects
of climate and land-use change in our predictions, using current climate
(temperature and precipitation) and land-use projections between 1950 and 2090. Local bacterial
richness will increase in all scenarios of climate and land-use change
considered, although this increase will be followed by a generalized community
homogenization process affecting more than 85% of terrestrial ecosystems.
Changes in the relative abundance of functional genes associated with the
increases in bacterial richness are also expected. Based on an ecological
cluster analysis our results suggest that phylotypes such as Geodermatophilus
sp. (typical desert bacteria), Mycobacterium sp. (which are known to include
important human pathogens), Streptomyces mirabilis (major producers of
antibiotic resistance genes), or potential fungal soil-borne plant pathogens
belonging to Ascomycota fungi (Venturia sp, Devriesia sp), will become more
abundant in their communities. Local bacterial
richness will increase in all scenarios of climate and land-use change
considered, although this increase will be followed by a generalized community
homogenization process affecting more than 85% of terrestrial ecosystems.
Changes in the relative abundance of functional genes associated with the
increases in bacterial richness are also expected. Based on an ecological
cluster analysis our results suggest that phylotypes such as Geodermatophilus
sp. (typical desert bacteria), Mycobacterium sp. (which are known to include
important human pathogens), Streptomyces mirabilis (major producers of
antibiotic resistance genes), or potential fungal soil-borne plant pathogens
belonging to Ascomycota fungi (Venturia sp, Devriesia sp), will become more
abundant in their communities. Our results provide evidence that climate change has a stronger
influence on soil microbial communities than land-use change (often including
deforestation and agricultural expansion), although most of the climate effects
are indirect through other environmental variables (e.g., changes in soil pH). The
same was found for microbial functions such as the prevalence of phosphate
transport genes. We provide reliable predictions about the changes in the
global distribution of microbial communities, showing an increase in alpha
diversity and a homogenization of soil microbial communities in the
Anthropocene.

土壤微生物对于维系生命维持的生态系统服务至关重要，然而，关于这些微生物在全球变化情景下如何受到影响的预测却尚显不足。因此，本研究旨在利用多种全球变化情景，对未来土壤微生物的分布进行预测。本研究采用跨越六大洲的全球土壤微生物群落数据库，估算土壤微生物组的历史和未来趋势。为此，我们运用结构方程模型，将气候和土地利用变化的直接与间接效应纳入预测之中，并利用1950年至2090年间的当前气候（温度和降水）以及土地利用预测。在考虑的所有气候和土地利用变化情景中，局部细菌丰富度均将增加，尽管这种增加将随后伴随着影响超过85%陆地生态系统的普遍群落同质化过程。与细菌丰富度增加相关的功能基因相对丰度的变化也预期将发生。基于生态聚类分析，我们的结果表明，诸如Geodermatophilus sp.（典型沙漠细菌）、Mycobacterium sp.（已知包含重要的人类病原体）、Streptomyces mirabilis（主要抗生素抗性基因的生产者）或可能属于子囊菌门的真菌土壤传播植物病原体（Venturia sp、Devriesia sp）等系谱型将在其群落中变得更加丰富。在考虑的所有气候和土地利用变化情景中，局部细菌丰富度均将增加，尽管这种增加将随后伴随着影响超过85%陆地生态系统的普遍群落同质化过程。与细菌丰富度增加相关的功能基因相对丰度的变化也预期将发生。基于生态聚类分析，我们的结果表明，诸如Geodermatophilus sp.（典型沙漠细菌）、Mycobacterium sp.（已知包含重要的人类病原体）、Streptomyces mirabilis（主要抗生素抗性基因的生产者）或可能属于子囊菌门的真菌土壤传播植物病原体（Venturia sp、Devriesia sp）等系谱型将在其群落中变得更加丰富。我们的研究结果提供了证据，表明气候变化对土壤微生物群落的影响强于土地利用变化（通常包括森林砍伐和农业扩张），尽管大多数气候效应是通过其他环境变量间接产生的（例如，土壤pH值的变化）。对于微生物功能，如磷酸盐转运基因的普遍性，也发现了同样的情况。我们提供了关于微生物群落全球分布变化的可靠预测，显示出α多样性的增加以及人类世土壤微生物群落的同质化。