KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
|Place of Conferral||新疆乌鲁木齐|
|Keyword||氮沉降 降水 增温 物种多样性 土壤养分 氮素损失 温带沙漠 Nitrogen Deposition Precipitation Species Diversity Soil Nutrient Nitrogen Gaseous Loss Temperate Desert|
气候变暖、降水格局和大气氮沉降是近年来备受关注的全球变化热点，它们能够影响植物群落生长、土壤养分以及气态氮素损失。然而，以前的研究大部分集中在森林与草原生态系统，目前有关干旱半干旱区荒漠生态系统如何对增温、降水和氮沉降增加响应的研究相对较少。荒漠生态系统降雨少，干旱高温，土壤含氮量低，与其它生态系统相比，增温、降水和氮沉降增加有可能带来更大的生态效应。因此，为探究大气氮沉降、降雨和气候变暖对温带沙漠植物群落、土壤养分和气态氮素损失（NH3 和 N2O）的影响， 2016 年 9 月到 2017 年 10 月在古尔班通古特沙漠开展了基于降水、氮沉降和增温相结合的多因子控制实验。结果如下：（1） 水、氮添加和增温均对荒漠植物群落生产力和多样性的影响不显著；水氮添加对植物群落多样性具有显著交互作用， 且显著减少了植物群落多样性。 荒漠草本植物群落整体对水、氮添加和增温响应不显著；但菊科和十字花科植物在地上地下生物量的分配上比牻牛儿苗科和禾本科植物对水氮的响应更敏感，牻牛儿苗科和菊科植物对升温比较敏感。（2）氮添加处理的土壤有机碳和全氮的含量显著增加， 而土壤全磷和全钾含量相对降低； 水添加和增温处理的土壤有机碳和全氮没有显著变化，但其土壤中磷钾的含量也相对降低；水氮添加对土壤氮磷有显著的交互作用。土壤化学计量比主要受控于土壤 C 和 N，土壤 C 比 N 更为缺乏。水添加、氮添加均显著降低了土壤 pH值，但增温反之；水氮温三因素对土壤电导率均没有显著影响。古尔班通古特沙漠土壤微生物生物量碳氮比介于 1.52-4.34，表明在古尔班通古特沙漠土壤微生物群落中细菌占据优势。（3）氮添加显著促进土壤氨挥发，增水和升温均对其影响不显著； 水氮对土壤氨挥发有显著的交互作用，水氮温整体上显著促进土壤氨挥发。荒漠土壤氨挥发存在显著的季节性变化，荒漠土壤氨挥发在春季递减过程中波动较大， 而在夏秋季较为规律。土壤温湿度在春季显著影响氨挥发， 在夏季土壤 pH 抑制土壤氨挥发， 同时土壤氨挥发也受到土壤铵态氮、植物群落生产力和多样性的调控。氮添加显著促进土壤 N2O 排放，增水和升温对其排放影响不显著，水氮温整体上显著促进了土壤N2O 排放。 N2O 具有明显的季节性变化，在春季土壤湿度与 N2O 通量显著负相关；在夏秋季，土壤湿度和铵根含量与 N2O 排放显著正相关而土壤 pH 与其负相关； 植物群落生产力和多样性也会间接地影响土壤 N2O 通量。
Global warming, precipitation patterns, nitrogen（N） deposition have become heatedissues of global change in recent years, which could affect the plant growth, soil nutrientand N gaseous loss. However, most previous studies focused on the forest and grassecosystems. Few researches were reported in desert ecosystems. Due to less precipitation,lower N concentration in soil, drought and high temperature, increasing temperature,precipitation and nitrogen deposition in desert ecosystems would lead to greater effectscompared with other ecosystems. Therefore, to understand the effects of atmosphericnitrogen deposition, precipitation and global warming on plant, soil nutrient and and Ngaseous loss in temperate desert ecosystem, a field multiple-factor experiment includingincreased precipitation, nitrogen addition and increasing temperature was conducted inthe Gurbantunggut Desert from September 2016 to October 2017. The main results aresummarized as follows:（1） Water, N addition and increasing temperature had no significant effects to plantproductivity and biodiversity; significant interaction effects of water and N addition onplant biodiversity and productivity were found. Water and N addition reduced plantbiodiversity, significantly. The responses of desert plants community to water, N additionand increasing temperature were not significant. However, Compositae and Brassicaceaespecies were more sensitive to water or nitrogen addition compared with Geraniaceaeand Grass species, while increasing temperature affected sensitively Geraniaceae andCompositae species in the aspect of above-and belowground biomass allocation.（2） In general, soil organic carbon (SOC) and total nitrogen (TN) increased buttotal phosphorus (TP) and potassium (TK) decreased in treatmeats of N addition ,significantly. Water addition and increasing temperature hadn’t significant effects on SOCand TN. The interactive effect of water and N addition on TN and TP can be found. Soilstoichiometric ratios were largely mediated by the contents of SOC and TN, and SOC wasmore limited than TN in the Gurbantunggut Desert. Water or N addition decreased soil pH, while soil pH was improved by increasing temperature. Increasing temperature, wateror N addition did not affect significantly soil electrical conductivity (EC). Owing to theratio of MBC to MBN ranging from 1.52 to 4.34, our results suggest that the bacteria holdadvantage in the soil microbial community in the Gurbantunggut Desert.（3） N addition promoted significantly ammonia volatilization that was not affectedsignificantly by water addition and increasing temperature. Obvious interaction effects onsoil ammonia volatilization was observed; increasing temperature, water and N additionaccelerated significantly soil ammonia volatilization. Ammonia volatilization showedobvious seasonal variations: variations of ammonia volatilization in spring decreased andfluctuated largely than that of summer and autumn. Soil temperature and moisture hadsignificant effects on soil ammonia volatilization in spring; ammonia volatilization wassuppressed by soil pH in autumn. Moreover, soil ammonia volatilization was influencedby soil NH4+-N, plant productivity and diversity. N addition tended to increasesignificantly N2O emissions in N treatments compared with the control; increasingtemperature and water addition motivate slightly soil N2O emissions. Increasingtemperature, water and N addition promote significantly N2O emissions. The N2Oemissions presented large seasonal variations in the study area. Soil humidity correlatednegatively with the fluxes of N2O in spring. The content of soil NH4+-N and soil humidityhad significant positive correlation with the fluxes of N2O, while soil pH negativelycorrelated with that of N2O in summer and autumn. The N2O emissions was affected bysoil NH4+-N, plant communities biomass and diversity.
|吴文超. 水氮温的增加对古尔班通古特荒漠植被、土壤化学计量特征和气态氮素损失的影响[D]. 新疆乌鲁木齐. 中国科学院大学,2018.|
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