Contrasting activation energies of litter-associated respiration and P uptake drive lower cumulative P uptake at higher temperatures
Contrasting activation energies of litter-associated respiration and P uptake drive lower cumulative P uptake at higher temperatures
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DOI：
10.5194/bg-20-191-2023
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发表时间：
2023-01
期刊：
影响因子：
4.9
通讯作者：
Nathan J. Tomczyk;A. Rosemond;A. Kaz;J. Benstead
中科院分区：
文献类型：
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作者：
Nathan J. Tomczyk;A. Rosemond;A. Kaz;J. Benstead
抽象。异养微生物在调节能量和营养物质通量方面发挥着关键作用，这些通量越来越受到全球变化的环境条件（如变暖和营养物质富集）的影响。虽然已经详细研究了温度和营养物质对微生物矿化碳的影响，但很少关注这些因素如何改变营养物质的吸收速率。我们使用实验室实验，同时评估温度依赖性的可溶性活性磷（SRP）的吸收和呼吸的叶凋落物相关的微生物群落从温带水源流。此外，我们评估的影响，初始浓度的SRP上的磷吸收的温度依赖性。最后，我们使用简单的模拟模型来推断我们的结果，并估计变暖和磷的可用性对累积总吸收的影响。我们发现，P吸收的温度依赖性低于呼吸（0.48对1.02 eV）。此外，磷吸收的温度依赖性随着SRP初始浓度的增加而增加，在11至212 µg L−1的初始SRP浓度梯度上，范围为0.12至0.48 eV。最后，尽管我们的实验室实验表明，随着温度的升高，特定质量的总磷吸收率增加，我们的模拟模型预测，随着变暖，累积磷吸收率下降，因为在较温暖的温度下呼吸速率的增加更迅速地耗尽底栖碳基质，从而减少了底栖微生物群落的生物量。因此，即使磷吸收的质量比率较高，在较温暖的温度下，累积磷吸收较低的脉冲输入的有机碳的停留时间。我们的研究结果强调，需要考虑气候变暖，营养物质的可用性，资源的可用性和/或碳加工的重要控制异养生态系统中的营养加工的幅度的综合影响。
Abstract. Heterotrophic microbes play key roles in regulating fluxes of energy and nutrients, which are increasingly affected by globally changing environmental conditions such as warming and nutrient enrichment. While the effects of temperature and nutrients on microbial mineralization of carbon have been studied in some detail, much less attention has been given to how these factors are altering uptake rates of nutrients. We used laboratory experiments to simultaneously evaluate the temperature dependence of soluble reactive phosphorus (SRP) uptake and respiration by leaf-litter-associated microbial communities from temperate headwater streams. Additionally, we evaluated the influence of the initial concentration of SRP on the temperature dependence of P uptake. Finally, we used simple simulation models to extrapolate our results and estimate the effect of warming and P availability on cumulative gross uptake. We found that the temperature dependence of P uptake was lower than that of respiration (0.48 vs. 1.02 eV). Further, the temperature dependence of P uptake increased with the initial concentration of SRP supplied, ranging from 0.12 to 0.48 eV over an 11 to 212 µg L−1 gradient in initial SRP concentration. Finally, despite our laboratory experiments showing increases in mass-specific rates of gross P uptake with temperature, our simulation models predict declines in cumulative P uptake with warming, because the increased rates of respiration at warmer temperatures more rapidly depleted benthic carbon substrates and consequently reduced the biomass of the benthic microbial community. Thus, even though mass-specific rates of P uptake were higher at the warmer temperatures, cumulative P uptake was lower over the residence time of a pulsed input of organic carbon. Our results highlight the need to consider the combined effects of warming, nutrient availability, and resource availability and/or magnitude on carbon processing as important controls of nutrient processing in heterotrophic ecosystems.