IMHE OpenIR  > 山地表生过程与生态调控重点实验室
水氮调控对高寒草原土壤微生物碳源利用的影响
Alternative TitleEffects of Water and Nitrogen on Soil Microbial Carbon Source Utilization in Alpine Steppe on the North Tibetan Plateau
张梦瑶
Subtype硕士
Thesis Advisor高永恒
2018
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline环境工程
Keyword高寒草原 水氮添加 土壤微生物代谢活性 碳源利用 土壤酶活性
Abstract近年来,降水格局改变和大气氮沉降加剧等全球变化现象改变着青藏高原高寒生态系统水、氮资源供给状况,从而影响着高原生态系统的结构和功能。本文以受水氮限制,平均海拔4500m以上的藏北高寒草原为研究对象,采集放牧和围栏禁牧样地土壤,分别设置4个水分(45%田间持水量(WHC)、60%WHC、75%WHC和90%WHC)和4个氮素添加水平(对照N0:0 g N m-2 a-1、低氮N2.5:2.5 g N m-2 a-1、中氮N5:5 g N m-2 a-1、高氮N10:10 g N m-2 a-1)进行室内培养和分析,探讨了不同梯度的水分和氮素添加及水氮交互作用对高寒草原土壤呼吸作用、土壤酶活性以及土壤微生物碳源利用的影响。主要研究结果如下:(1)藏北高寒草原土壤水分含量由45%WHC增加到75%WHC,土壤溶解性有机碳(DOC)、土壤微生物量碳(MBC)、土壤微生物量氮(MBN)、脲酶、磷酸酶含量也随之增加,但提高土壤含水量抑制了无机氮矿化速率;氮添加对DOC没有显著影响,但显著降低了土壤酶活性,提高了无机氮矿化速率,而且氮添加量越高无机氮矿化率越大;水氮交互处理未对土壤DOC、MBC、MBN、脲酶、磷酸酶和蔗糖酶产生显著影响。(2)土壤CO2累积排放量与土壤DOC含量显著相关,土壤水分含量的增加抑制了土壤CO2累计排放量,90%WHC水分条件的土壤呼吸作用比45%WHC小32.23%;氮添加对藏北高寒草原土壤呼吸作用的影响依赖于土壤水分状况,低氮处理(2.5 g N m-2 a-1)能显著激发高寒草原>60%WHC水分条件时的土壤CO2释放,而<60%WHC水分土壤条件下的土壤呼吸对高氮处理(10 g N m-2 a-1)有积极响应。(3)藏北高寒草原土壤微生物丰富度指数、优势度指数和均匀度指数分别介于1.59~3.20、0.70~0.96和0.92~1.51范围内。土壤微生物丰富度和优势度指数与高寒土壤溶解态有机物含量显著正相关,因此提高土壤水分含量(<75%WHC)增加了土壤微生物丰富度和优势度指数;但氮添加、水氮交互作用对土壤微生物丰富度指数、优势度指数和均匀度指数没有显著影响。(4)增加土壤水分含量提高了藏北高寒草原土壤微生物代谢活性(AWCD值),低氮处理(2.5 g N m-2 a-1)显著促进了放牧草原土壤微生物的代谢活性。水氮交互作用对土壤微生物代谢活性有显著影响,当土壤水分含量<60%WHC时,施氮能促进土壤微生物代谢活性,当土壤水分>60%WHC时,氮添加抑制了土壤微生物活性,并且氮添加量越高抑制作用越明显。 (5)藏北高寒草原土壤微生物利用的碳源种类以碳水化合物、氨基酸类、羧酸类和多聚物为主。增加土壤水分含量降低了土壤微生物碳源利用率,改变了碳源利用种类,随土壤水分含量增高,土壤微生物碳源利用种类由碳水化合物和氨基酸类碳源转变为胺类物质;氮添加能促进土壤微生物对胺类和多聚物类碳源的利用;水氮交互作用提高了土壤微生物对碳水化合物、氨基酸类和羧酸类碳源的利用。
Other AbstractIn recent years, global change such as precipitation pattern change and nitrogen deposition alters the supply of water and nitrogen resources in the alpine steppe, and it affects the structure and function of alpine ecosystem. In this paper, we took the alpine steppe in northern Tibetan as study site which average altitude is above 4500m, and 4 water addition control (45%WHC, 60%WHC, 75%WHC and 90%WHC) and 4 nitrogen addition levels (control group N0: 0 g N m-2 a-1, low nitrogen addition N2.5: 2.5 g N m-2 a-1, middle nitrogen addition N5: 5 g N m-2 a-1, high nitrogen addition N10: 10 g N m-2 a-1) were set up for indoor incubation. We analyzed the influence of different water and nitrogen addition and their interaction on soil respiration, soil enzyme activity and soil microbial utilization of carbon source in alpine steppe. The main results are as follows:(1) In alpine steppe, the soil moisture content increased from 45%WHC to 75%WHC, and the content of soil dissolved organic carbon (DOC), soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), urease and phosphatase also increased, and the mineralization rate of inorganic nitrogen was inhibited. Nitrogen addition had no significant effect on DOC, but it significantly reduced the activity of soil enzyme, increased the mineralization rate of inorganic nitrogen, and the higher the nitrogen adding level, the greater the mineralization intensity of inorganic nitrogen. The interaction of water and nitrogen did not produce significant effects on soil DOC, MBC, MBN, urease, phosphatase and invertase.(2) The cumulative emission of soil CO2 was significantly correlated with soil DOC content. The increase of soil water content inhibited the cumulative emission of CO2 in soil, while soil respiration in 90%WHC water condition decreased by 32.23% compared with 45%WHC. The response of soil respiration to nitrogen addition depended on the soil water condition, and low nitrogen treatment (2.5 g N m-2 a-1) can significantly stimulate the release of soil CO2 in the enclosing and > 60%WHC water conditions of grazing steppe, while the soil respiration under the condition of < 60%WHC water soil has a positive response to the high nitrogen treatment (10g N m-2 a-1). (3) Soil microbial richness index, dominance index and evenness index of alpine steppe in northern Tibet are in the range of 1.59~3.20, 0.70~0.96 and 0.92~1.51 respectively. Soil microbial richness and dominance index were significantly positively correlated with dissolved organic matter content in alpine soil, so soil microbial richness and dominance index were increased with the soil water content increasing (<75%WHC). But nitrogen addition and water and nitrogen interaction had no significant influence on soil microbial richness index, dominance index and evenness index.(4) The appropriate increase of soil moisture content could maintain a high level of microbial metabolic activity (AWCD) in the alpine steppe of northern Tibet, and 2.5 g N m-2 a-1 significantly improved the metabolic activity of soil microbes in enclosing grassland. The interaction of water and nitrogen has a significant effect on soil microbial metabolic activity. When soil water content is < 60%WHC, nitrogen addition promotes soil microbial metabolic activity. When soil moisture is > 60%WHC, nitrogen addition inhibits soil microbial activity, and the higher the nitrogen adding level, the more obvious inhibition effect.(5) The carbon sources of soil microbes in the alpine steppe of northern Tibet are mainly carbohydrates, amino acids, carboxylic acids and polymers. The increase of soil water content reduced the utilization of soil microbial carbon sources, and the utilization of soil microbial carbon sources changed from carbohydrates and amino acids to amines. Nitrogen addition promoted the use of soil microbes to amines carbon sources in grazing land, and the soil microbes in the enclosing steppe partial polymer carbon source. Water and nitrogen interaction had no significant influence on the utilization of soil microbial carbon sources, but generally improved the utilization of carbohydrates, amino acids and carboxylic acids. 
Pages102
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24770
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
张梦瑶. 水氮调控对高寒草原土壤微生物碳源利用的影响[D]. 北京. 中国科学院大学,2018.
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