Broderick Caitlin M, Benucci Gian Maria Niccolò, Bachega Luciana Ruggiero, Miller Gabriel D, Evans Sarah E, Hawkes Christine V
W.K. Kellogg Biological Station, Michigan State University, 3700 Gull Lake Drive, Hickory Corners, MI 49060, United States.
Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, United States.
ISME J. 2025 Jan 2;19(1). doi: 10.1093/ismejo/wraf005.
Long-term climate history can influence rates of soil carbon cycling but the microbial traits underlying these legacy effects are not well understood. Legacies may result if historical climate differences alter the traits of soil microbial communities, particularly those associated with carbon cycling and stress tolerance. However, it is also possible that contemporary conditions can overcome the influence of historical climate, particularly under extreme conditions. Using shotgun metagenomics, we assessed the composition of soil microbial functional genes across a mean annual precipitation gradient that previously showed evidence of strong climate legacies in soil carbon flux and extracellular enzyme activity. Sampling coincided with recovery from a regional, multi-year severe drought, allowing us to document how the strength of climate legacies varied with contemporary conditions. We found increased investment in genes associated with resource cycling with historically higher precipitation across the gradient, particularly in traits related to resource transport and complex carbon degradation. This legacy effect was strongest in seasons with the lowest soil moisture, suggesting that contemporary conditions-particularly, resource stress under water limitation-influences the strength of legacy effects. In contrast, investment in stress tolerance did not vary with historical precipitation, likely due to frequent periodic drought throughout the gradient. Differences in the relative abundance of functional genes explained over half of variation in microbial functional capacity-potential enzyme activity-more so than historical precipitation or current moisture conditions. Together, these results suggest that long-term climate can alter the functional potential of soil microbial communities, leading to legacies in carbon cycling.
长期气候历史会影响土壤碳循环速率，但这些遗留效应背后的微生物特征尚未得到充分理解。如果历史气候差异改变了土壤微生物群落的特征，尤其是那些与碳循环和胁迫耐受性相关的特征，就可能产生遗留效应。然而，当代条件也有可能克服历史气候的影响，特别是在极端条件下。我们使用鸟枪法宏基因组学，在一个年平均降水量梯度上评估了土壤微生物功能基因的组成，该梯度先前显示出土壤碳通量和胞外酶活性存在强烈气候遗留效应的证据。采样与从一场区域性、持续多年的严重干旱中恢复的时间相吻合，这使我们能够记录气候遗留效应的强度如何随当代条件而变化。我们发现，随着整个梯度上历史降水量的增加，与资源循环相关的基因投入增加，特别是在与资源运输和复杂碳降解相关的特征方面。这种遗留效应在土壤湿度最低的季节最为明显，这表明当代条件——特别是水分限制下的资源胁迫——会影响遗留效应的强度。相比之下，对胁迫耐受性的投入并未随历史降水量而变化，这可能是由于整个梯度上频繁出现周期性干旱。功能基因相对丰度的差异解释了微生物功能能力——潜在酶活性——超过一半的变异，比历史降水量或当前湿度条件的解释力更强。总之，这些结果表明，长期气候可以改变土壤微生物群落的功能潜力，从而导致碳循环中的遗留效应。
