Drivers of the microbial metabolic quotient across global grasslands
Drivers of the microbial metabolic quotient across global grasslands
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DOI：
10.1111/geb.13664
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发表时间：
2023-04
影响因子：
6.4
通讯作者：
A. Risch;S. Zimmermann;M. Schütz;E. Borer;A. Broadbent;M. Caldeira;K. Davies;N. Eisenhauer;
中科院分区：
文献类型：
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作者：
A. Risch;S. Zimmermann;M. Schütz;E. Borer;A. Broadbent;M. Caldeira;K. Davies;N. Eisenhauer;
微生物代谢商（MMQ; mg CO2-C/mg MBC/h）定义为每单位微生物生物量C（MBC; mg C/kg土壤）所呼吸的微生物CO2量（MR; mg CO2-C/kg土壤/h），是理解碳（C）循环（包括土壤固碳）微生物调节的关键参数。在这里，我们通过实验测试了关于多种营养素添加（氮+磷+钾+微量营养素）和植食动物排除对23个地点（五大洲）的MR，MBC和MMQ的个体和交互作用的假设。我们的网站涵盖了广泛的土壤气候条件;因此，我们评估了哪些土壤气候变量影响MMQ最多，以及它们如何与我们的治疗相互作用。位置澳大利亚，亚洲，欧洲，北/南美洲。时间段2015 - 2016。主要类群土壤微生物。方法从已建立的实验治疗的地块收集土壤。在不添加葡萄糖的5周实验室孵育中评估MR，通过底物诱导呼吸进行MBC。MMQ计算为MR/MBC，并根据土壤温度进行校正（MMQsoil）。使用线性混合效应模型（LIFE）和结构方程模型（SEMs），我们分析了如何土壤气候特征和治疗交互影响MMQ soil. ResultsMMQ土壤是较高的位置，较高的年平均温度，较低的持水量和较低的土壤有机C浓度，但没有响应我们的治疗跨站点的MR也MBC改变。我们将这种相对的内稳态归因于我们的治疗方法对土壤气候变量的调节影响。例如，草食动物排除，无论施肥，导致更大的MMQ土壤只有在网站与较低的土壤有机C（< 1.7%）。主要conclusionsOur结果查明了主要变量相关的MMQ土壤在草原和强调当地土壤气候条件的重要性，在控制响应的C循环人为压力。通过测试全球土壤气候梯度MMQ土壤的假设，这项工作也有助于调整以前的研究相互矛盾的结果。
AimThe microbial metabolic quotient (MMQ; mg CO2‐C/mg MBC/h), defined as the amount of microbial CO2respired (MR; mg CO2‐C/kg soil/h) per unit of microbial biomass C (MBC; mg C/kg soil), is a key parameter for understanding the microbial regulation of the carbon (C) cycle, including soil C sequestration. Here, we experimentally tested hypotheses about the individual and interactive effects of multiple nutrient addition (nitrogen + phosphorus + potassium + micronutrients) and herbivore exclusion on MR, MBC and MMQ across 23 sites (five continents). Our sites encompassed a wide range of edaphoclimatic conditions; thus, we assessed which edaphoclimatic variables affected MMQ the most and how they interacted with our treatments.LocationAustralia, Asia, Europe, North/South America.Time period2015–2016.Major taxaSoil microbes.MethodsSoils were collected from plots with established experimental treatments. MR was assessed in a 5‐week laboratory incubation without glucose addition, MBC via substrate‐induced respiration. MMQ was calculated as MR/MBC and corrected for soil temperatures (MMQsoil). Using linear mixed effects models (LMMs) and structural equation models (SEMs), we analysed how edaphoclimatic characteristics and treatments interactively affected MMQsoil.ResultsMMQsoil was higher in locations with higher mean annual temperature, lower water holding capacity and lower soil organic C concentration, but did not respond to our treatments across sites as neither MR nor MBC changed. We attributed this relative homeostasis to our treatments to the modulating influence of edaphoclimatic variables. For example, herbivore exclusion, regardless of fertilization, led to greater MMQsoil only at sites with lower soil organic C (< 1.7%).Main conclusionsOur results pinpoint the main variables related to MMQsoil across grasslands and emphasize the importance of the local edaphoclimatic conditions in controlling the response of the C cycle to anthropogenic stressors. By testing hypotheses about MMQsoil across global edaphoclimatic gradients, this work also helps to align the conflicting results of prior studies.