长期增温和氮素添加对荒漠草原不同植物功能群特征的影响

Effects of long-term warming and nitrogen addition on characteristics of different plant functional groups in desert steppe

摘要:

为揭示短花针茅(Stipa breviflora)荒漠草原植物功能群对长期增温和氮素添加的响应机制,以内蒙古四子王旗短花针茅荒漠草原为研究对象,于2019年8月对连续13年(2006-2019)增温和氮素添加试验下的植物物种组成,高度、盖度、密度进行观测,并对功能群地上生物量、多样性进行分析。结果表明:增温对多年生杂类草的盖度有显著影响,增幅达66.3%,氮素添加处理下一、二年生植物的盖度和密度分别减少了53%和71%;氮素添加处理对多年生杂类草的地上生物量有显著影响,降幅达46.1%;氮素添加对多年生禾草和多年生杂类草的Margalef指数有显著影响,Margalef指数、Shannon-Wiener指数和Pielou指数在增温处理下变化不大;增温+氮素添加处理下多年生杂类草和多年生禾草重要值极大,灌木和半灌木、一、二年生植物重要值极小。长期增温和氮素添加改变了短花针茅荒漠草原植物群落的组成和结构,进而促进了草地的可持续利用。

Abstract:

In order to reveal the response mechanism of plant functional groups to long-term warming and nitrogen addition in a desert steppe,this study took Stipa breviflora of desert steppe in the Siziwang Banner of Inner Mongolia as the research object.In August 2019,the plant species composition,height,coverage and density were observed under the control of temperature increase and nitrogen addition for 13 years (2006 ~ 2019) in the experimental site.Above ground biomass as well as species diversity were also analyzed.The results showed that Increasing temperature had a significant effect on the coverage of perennial grass,with an increase of 66.3%,and the coverage and density of the first and second year plants decreased by 53% and 71% respectively under nitrogen addition.The results aslo demonstrated that the Margalef index of perennial grass and perennial hybrid grass was significantly affected by nitrogen addition nitrogen addition had a significant effect on the aboveground biomass of perennial grasses,with a decrease of 46.1%;meanwhile,Margalef index,Shannon-Wiener index and Pielou index had little change under the warming treatment;besides,the importance values of perennial grass and perennial grass were extremely high under warming and nitrogen addition treatment,while the importance values of shrubs and semi-shrubs and first and biennial plants were extremely low.In conclusion,long-term warming and nitrogen addition changed the composition and structure of plant community in Stipa breviflora desert steppe,and promoted the sustainable utilization of grassland.