土壤氮转化对氮添加的响应主要与人工油松林中功能基因相对丰度的变化有关。
The responses of soil nitrogen transformation to nitrogen addition are mainly related to the changes in functional gene relative abundance in artificial Pinus tabulaeformis forests.
机构信息
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi Province, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi Province, China; Institute of Soil and Water Conservation, Chinese Academy of Science and Ministry of Water Resources, Yangling 712100, Shaanxi, China.
出版信息
Sci Total Environ. 2020 Jun 25;723:137679. doi: 10.1016/j.scitotenv.2020.137679. Epub 2020 Mar 5.
The increase of soil nitrogen (N) availability may alter soil microbial community composition and the natural N cycle in forest ecosystems. However, the responses of soil microbial nitrogen functional genes (NFGs) to N addition and their consequent effect on the N-cycle processes are poorly understood. In this study, soil samples were collected from an artificial Pinus tabulaeformis forest located in Loess Plateau (China) to which N at four different concentrations was added (0 [N0], 3 [N3], 6 [N6], and 9 [N9] g N m y) for 4 years. We quantified the relative abundance of NFGs using functional gene microarray GeoChip 5.0 and determined net N transformation and NO emission rates in a 14-day incubation experiment. The results showed that N3 and N6 treatments did not significantly affect the total relative abundance and diversity of NFGs assemblage but significantly increased the relative abundance of specific genes for the NH cycle (ureC, nirA, and nrfA), and nitrification (amoA) and denitrification (norB). These positive effects were related to the increase in soil organic C, NO-N, and microbial biomass C (MBC). N9 treatment significantly decreased the relative abundance of all NFGs, and this negative impact was correlated with reduced dissolved organic C and MBC. Moreover, N addition significantly changed net N nitrification, mineralization, and NO emission rates, and NFGs explained the higher variances in the N transformation processes than soil properties. Specifically, ammonia-oxidizing archaea (amoA-AOB) and MBC were the key factors related to net N nitrification; ureC, nirK, and MBC were the key factors related to net N mineralization; and narG and nirS were the key factors related to NO emission. Our results show that global N deposition may mainly influence N transformation processes by regulating the corresponding NFG relative abundance, thereby affecting the N cycle in forest soils.
土壤氮（N）有效性的增加可能会改变森林生态系统中土壤微生物群落的组成和自然 N 循环。然而，对于 N 添加对土壤微生物氮功能基因（NFG）的响应及其对 N 循环过程的后续影响，我们知之甚少。在这项研究中，从位于黄土高原（中国）的人工油松人工林中采集了土壤样本，该林分中施加了 4 种不同浓度的 N（0 [N0]、3 [N3]、6 [N6] 和 9 [N9] g N m y），为期 4 年。我们使用功能基因微阵列 GeoChip 5.0 定量了 NFG 的相对丰度，并在 14 天的培养实验中测定了净 N 转化和 NO 排放速率。结果表明，N3 和 N6 处理并未显著影响 NFG 组合的总相对丰度和多样性，但显著增加了 NH 循环（ureC、nirA 和 nrfA）、硝化（amoA）和反硝化（norB）特定基因的相对丰度。这些积极影响与土壤有机 C、NO-N 和微生物生物量 C（MBC）的增加有关。N9 处理显著降低了所有 NFG 的相对丰度，这种负面影响与溶解有机 C 和 MBC 的减少有关。此外，N 添加显著改变了净 N 硝化、矿化和 NO 排放速率，并且 NFG 比土壤性质解释了 N 转化过程中更高的方差。具体而言，氨氧化古菌（amoA-AOB）和 MBC 是与净 N 硝化相关的关键因素；ureC、nirK 和 MBC 是与净 N 矿化相关的关键因素；narG 和 nirS 是与 NO 排放相关的关键因素。我们的结果表明，全球 N 沉积可能主要通过调节相应的 NFG 相对丰度来影响 N 转化过程，从而影响森林土壤中的 N 循环。
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