Departamento de Biología y Geología, Física y Química Inorgánica, Universidad Rey Juan Carlos, Madrid, Spain.
School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA.
Nat Ecol Evol. 2019 Feb;3(2):232-238. doi: 10.1038/s41559-018-0770-5. Epub 2019 Jan 14.
Heterotrophic soil microbial respiration-one of the main processes of carbon loss from the soil to the atmosphere-is sensitive to temperature in the short term. However, how this sensitivity is affected by long-term thermal regimes is uncertain. There is an expectation that soil microbial respiration rates adapt to the ambient thermal regime, but whether this adaptation magnifies or reduces respiration sensitivities to temperature fluctuations remains unresolved. This gap in understanding is particularly pronounced for drylands because most studies conducted so far have focused on mesic systems. Here, we conduct an incubation study using soil samples from 110 global drylands encompassing a wide gradient in mean annual temperature. We test how mean annual temperature affects soil respiration rates at three assay temperatures while controlling for substrate depletion and microbial biomass. Estimated soil respiration rates at the mean microbial biomass were lower in sites with higher mean annual temperatures across the three assayed temperatures. The patterns observed are consistent with expected evolutionary trade-offs in the structure and function of enzymes under different thermal regimes. Therefore, our results suggest that soil microbial respiration adapts to the ambient thermal regime in global drylands.
异养土壤微生物呼吸作用是土壤向大气中释放碳的主要过程之一，其对温度的短期响应较为敏感。然而，长期热环境如何影响这种敏感性尚不确定。人们普遍认为，土壤微生物呼吸速率会适应环境的热环境，但这种适应是会增加还是减少对温度波动的呼吸敏感性仍未解决。由于迄今为止大多数研究都集中在中湿系统，因此在干旱地区，这种理解上的差距尤其明显。在这里，我们使用来自全球 110 个干旱地区的土壤样本进行了一项培养研究，这些样本涵盖了平均年温度的广泛梯度。我们在三个测定温度下测试了平均年温度如何影响土壤呼吸速率，同时控制了基质消耗和微生物生物量。在三个测定温度下，在平均年温度较高的地点，估计的微生物生物量的土壤呼吸速率较低。所观察到的模式与不同热环境下酶的结构和功能的预期进化权衡一致。因此，我们的结果表明，全球干旱地区的土壤微生物呼吸作用适应了环境的热环境。
