Unexpected microbial metabolic responses to elevated temperatures and nitrogen addition in subarctic soils under different land uses
Unexpected microbial metabolic responses to elevated temperatures and nitrogen addition in subarctic soils under different land uses
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DOI：
10.1007/s10533-022-00943-7
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发表时间：
2022-06
期刊：
影响因子：
4
通讯作者：
J. Schroeder;Tino Peplau;E. Gregorich;C. Tebbe;C. Poeplau
中科院分区：
文献类型：
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作者：
J. Schroeder;Tino Peplau;E. Gregorich;C. Tebbe;C. Poeplau
亚北极地区尤其受到全球变暖的影响。随着植被期的延长，北方森林可以逐渐转变为农业用地。土地利用如何改变土壤有机质分解对温度上升的敏感性，或者氮(N)肥等养分有效性的变化如何影响碳(C)循环，都是未知的。微生物碳利用效率（CUE）定义了分解后的土壤有机碳有多少是直接生长的，多少是流失到大气中的。以加拿大育空地区3个亚北极土壤为研究对象，研究了CUE （24 h）和土壤有机质分解（50 d）对+ 10°C升温和N添加的响应。与我们基于文献的预期相反，北方森林土壤对增温和N添加的响应并不敏感。温度敏感性不受土地利用类型的影响。与一般假设的下降相反，短期变暖使CUE增加了+ 30%，这与微生物生长正相关。氮的添加使总体CUE降低了- 7%，与预期的CUE会因营养限制的缓解而升高相反。对N添加的响应与真菌与细菌的比例呈负相关，并且可能取决于普遍的氮肥制度。微生物代谢的温度敏感性受样地特定参数驱动，而不受土地利用类型驱动。我们的研究结果表明，在模拟未来气候条件下土壤有机碳动态时，可能没有必要考虑特定土地利用的温度敏感性。
Subarctic regions are particularly affected by global warming. As vegetation periods lengthen, boreal forests could gradually be converted into agricultural land. How land use alters the susceptibility of soil organic matter decomposition to rising temperatures or how changes in nutrient availability, such as nitrogen (N) fertilisation, affect carbon (C) cycling is unknown. Microbial carbon use efficiency (CUE) defines how much of the decomposed soil organic carbon is directed to growth or lost to the atmosphere. Here, we investigated the response of CUE (24 h) and soil organic matter decomposition (50 days) to + 10 °C warming and N addition in three subarctic soils derived from paired plots (forest, grassland, cropland) in the Yukon, Canada. Contrary to our literature-based expectations, boreal forest soils did not demonstrate the most sensitive response to warming and N addition. Temperature sensitivity was not affected by land-use type. In contrast to a generally assumed decline, short-term warming increased CUE by + 30%, which was positively correlated with microbial growth. N addition reduced overall CUE by − 7%, in contrast to the expectation that CUE would rise due to the alleviation of nutrient limitations. The response to N addition was negatively correlated with the ratio of fungi to bacteria, and presumably depended on the prevailing N-fertilisation regime. The temperature sensitivity of microbial metabolism was driven by site-specific parameters rather than by land-use type. Our results indicate that it may not be necessary to consider land use-specific temperature sensitivities when modelling soil organic carbon dynamics under future climate conditions.