中文关键词盐渍化草地氮、磷添加氨氧化微生物细菌真菌 英文关键词saline-alkaline grasslandnitrogen and phosphorus additionammonia-oxidizing microorganismsbacteriafungi

作者	单位	E-mail
杨建强	山西农业大学生命科学学院, 太谷 030801	robert_free@163.com
刁华杰	山西农业大学草业学院, 太谷 030801 中国科学院植物研究所植被与环境变化国家重点实验室, 北京 100093 山西右玉黄土高原草地生态系统定位观测研究站, 右玉 037200
胡姝娅	中国科学院植物研究所植被与环境变化国家重点实验室, 北京 100093 中国科学院大学, 北京 100049
陈晓鹏	山西农业大学草业学院, 太谷 030801 中国科学院植物研究所植被与环境变化国家重点实验室, 北京 100093 山西右玉黄土高原草地生态系统定位观测研究站, 右玉 037200
王常慧	山西农业大学草业学院, 太谷 030801 中国科学院植物研究所植被与环境变化国家重点实验室, 北京 100093 山西右玉黄土高原草地生态系统定位观测研究站, 右玉 037200	wangch@ibcas.ac.cn

中文摘要 盐渍化草地土壤养分含量低，自然条件差，尤其是大量元素氮和磷的含量低于天然非盐渍化草地.盐渍化草地中的土壤微生物由于长期受盐或碱的胁迫，群落组成与结构也区别于非盐渍化天然草地.盐渍化草地土壤微生物受养分限制叠加盐碱胁迫如何响应氮、磷添加的机制尚不清楚.本研究在山西省右玉县境内的盐渍化草地进行，2017年建立了氮磷添加实验平台，包括对照、氮添加、磷添加及氮和磷同时添加的4个处理，于实验处理的第3年（2020年）测定生长季5~9月氨氧化微生物（氨氧化细菌：AOB和氨氧化古菌：AOA）、土壤真菌（fungi，F）和细菌（bacteria，B）的组成以及土壤微生物生物量碳（MBC）和微生物生物量氮（MBN），结合土壤盐基阳离子及pH值的变化，探讨盐渍化草地土壤微生物特征对氮、磷添加的响应及其机制.结果表明：①2020年5~9月，采样时间显著影响土壤AOA和AOB的丰度、细菌真菌组成及微生物生物量；土壤微生物的季节动态是由土壤含水量，生长季降水分配及植物因素共同调控的.②与对照组相比，AOA/AOB的比值在氮添加处理下显著降低51%；磷添加对土壤微生物特征（氨氧化微生物、细菌真菌组成和微生物生物量）无显著影响；在氮和磷同时添加处理下，AOB的丰度显著提高了64.1%，AOA的丰度无显著改变，但AOA/AOB显著降低59.6%.③单独氮或磷添加对土壤pH值无显著影响，但氮和磷同时添加显著降低了土壤pH值；尽管氮、磷添加对土壤盐基阳离子无显著影响，结构方程模型结果显示，土壤盐基阳离子对土壤微生物（细菌和真菌组成）具有直接的调控作用.④土壤含水量对土壤微生物的变异具有较高的解释度.因此，本研究表明AOB对养分添加的响应比较敏感，短期氮和磷添加提高AOB的数量，促进氮的周转. 英文摘要 Soil microbial composition and community structure in salinization grassland are substantially different from those of non-saline-alkaline natural grassland due to the lower soil nutrients, inferior natural conditions, and higher soil salinization stress. Nitrogen (N) and phosphorus (P) are main factors that limit the productivity in semi-arid grassland, and whether soil microorganisms are affected by the addition of N and P in nutrient limitation and salinization grassland is still unclear. This experiment was conducted in Youyu Loess Plateau Grassland Ecosystem Research Station, Shanxi Province. Four treatments were set in 2017, which included the control (CK), N addition (N), P addition (P), and N and P addition (NP). The ammonia-oxidizing microorganisms[i.e., ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA)], soil bacteria (B) and fungi (F) composition, and soil microbial biomass carbon and nitrogen (MBC and MBN, respectively), as well as soil pH and base cations, were measured during the growing season in 2020. Our results showed that:① the sampling month had the main effect on soil ammonia-oxidizing microorganisms, soil bacterial and fungal composition, and microbial biomass, which were regulated by precipitation distribution, soil water content, and plant factors. ② Compared with that under the control, the ratio of AOA/AOB was significantly decreased by 51% under N addition, whereas P addition had no significant effect on soil microbial characteristics (ammonia-oxidizing microorganisms, bacterial and fungal composition, and microbial biomass). However, the NP treatment significantly increased AOB by 64.1% and decreased the ratio of AOA/AOB by 59.6%. ③ Single addition of N and P had no significant effect on soil pH, whereas the simultaneous addition of N and P significantly reduced soil pH. Though N and P additions had no significant effect on soil base cations, structural equation models (SEM) showed that soil base cations had a direct regulatory effect on soil microorganisms (bacterial and fungal composition). ④ Soil water content had the highest explanatory power for the variation in soil microorganisms based on the results of the SEM. In conclusion, our study shows that soil AOB is more sensitive to nutrient addition, and short-term nutrient addition could increase the abundance of AOB, thus promoting nutrient transformation.

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