Wu Jiangqi, Wang Haiyan, Li Guang
College of Forestry, Gansu Agricultural University, Lanzhou, China.
College of Urban Environment, Lanzhou City University, Lanzhou, China.
Front Microbiol. 2024 Dec 18;15:1472792. doi: 10.3389/fmicb.2024.1472792. eCollection 2024.
Alpine wet meadows are known as NO sinks due to nitrogen (N) limitation. However, phosphate addition and N deposition can modulate this limitation, and little is known about their combinative effects on NO emission from the Qinghai-Tibet Plateau in wet meadows. This study used natural wet meadow as the control treatment (CK) and conducted experiments with N (CONH addition, N15), P (NaHPO addition, P15), and their combinations (CONH and NaHPO addition, N15P15) to investigate how N and P supplementation affected soil NO emissions in wet meadow of QTP. Contrary to previous studies on grasslands, the effect of phosphate addition treatment on soil NO flux was not detectable during the growing seasons of 2019 and 2020. Over a span of two years, the N addition treatment significantly increased the NO flux by 3.45 μg⋅m⋅h due to increased soil N availability. Noticeably, phosphate addition intensified the effect of N deposition treatment on soil NO flux with high significance in the early growth season of 2020. This augmentation can be attributed to the alleviation of limiting factors imposed by plants and microorganisms on soil N and P, fostering the mineralization and decomposition of litter and soil nutrients by microorganisms. Consequently, the results showed that total nitrogen and nitrate nitrogen were the main controls on soil NO emission under N and P addition. In addition, redundancy analysis showed that the relative abundance of genes in soil microorganisms (, , , , ) is the main factor affecting NO flux and available nitrogen. We project that if nutrient input continues to increase, the main limiting factor of soil will change from N restriction to P restriction due to the unique microbial nitrogen conversion process in the alpine meadow, significantly increasing NO emissions. Consequently, the heightened contribution of alpine wet meadows to global warming and ozone depletion hinges on the dynamics of nutrient input regimes, spotlighting the urgent need for informed environmental management strategies.
由于氮（N）限制，高山湿草甸被认为是一氧化氮（NO）的源汇。然而，添加磷酸盐和氮沉降可以调节这种限制，而它们对青藏高原湿草甸NO排放的综合影响却知之甚少。本研究以天然湿草甸作为对照处理（CK），并进行了添加氮（CONH添加，N15）、磷（NaHPO添加，P15）及其组合（CONH和NaHPO添加，N15P15）的实验，以研究氮和磷添加如何影响青藏高原湿草甸土壤NO排放。与先前关于草地的研究相反，在2019年和2020年的生长季节中，未检测到添加磷酸盐处理对土壤NO通量的影响。在两年的时间里，由于土壤氮有效性的增加，添加氮处理显著增加了NO通量，增加了3.45μg·m·h。值得注意的是，在2020年生长季早期，添加磷酸盐显著增强了氮沉降处理对土壤NO通量的影响。这种增强可归因于植物和微生物对土壤氮和磷施加的限制因素的缓解，促进了微生物对凋落物和土壤养分的矿化和分解。因此，结果表明，总氮和硝态氮是氮磷添加条件下土壤NO排放的主要控制因素。此外，冗余分析表明，土壤微生物中某些基因（具体基因未明确写出）的相对丰度是影响NO通量和有效氮的主要因素。我们预测，如果养分输入持续增加，由于高山草甸独特的微生物氮转化过程，土壤的主要限制因素将从氮限制转变为磷限制，显著增加NO排放。因此，高山湿草甸对全球变暖和臭氧层损耗的贡献增加取决于养分输入模式的动态变化，凸显了制定明智的环境管理策略的迫切需求。
