三江源区不同年限黑土滩人工草地植被特征

Vegetation Characteristics of Black Soil Land Artificial Grassland of Different Years in Source Area of Three Rivers

以三江源区不同建植年限黑土滩人工草地(1、3、7、12、17、21和24龄)及其周边黑土滩(CK)为对象,从植被群落结构、生物量、物种多样性角度,探究三江源区黑土滩人工草地植被变化特征及适宜利用年限,为黑土滩人工草地的合理利用提供理论依据。结果表明:随建植年限增加,人工草地草层的高度和盖度及地上生物量均呈增加趋势,且人工草地比CK高;人工草地的禾本科高度、盖度、地上生物量、地下生物量均高于莎草科、豆科和杂类草,CK样地杂类草高于其他经济类群;各建植年限人工草地优势种和伴生种分别为垂穗披碱草(Elymus nutans)和青海冷地早熟禾(Poa crymophila),且其重要值均随建植年限增加呈逐渐增加趋势;各经济类群物种多样性指数均呈波动式增加趋势,建植3 a人工草地的植物香农维纳指数和均匀度指数最低,分别为0.66、0.48,建植21 a时最高;在植物NMDS分析表明,建植24 a、建植21 a和建植12 a的人工草地与CK样地无重合部分,其植被群落差异度很大。研究得知:建植21 a的黑土滩人工草地群落多样性指数显著高于其他建植年限的人工草地,与黑土滩退化草地相似度最小,群落组成相对稳定。

The black soil land artificial grasslands(1,3,7,12,17,21,24 years old)and its surrounding black soil lands(CK)in the source area of three rivers were selected as the research objects,and the vegetation community structure,biomass and species composition were investigated to clarify its vegetation characteristics and suitable utilization years for black soil land artificial grassland in the source area of the three rivers,so as to provide a theoretical basis for the rational utilization of black soil land artificial grassland.The results showed that:With the increase of planted years,the height,coverage and aboveground biomass of artificial grassland communities all show a rising trend,which were higher than that of CK;in plant economic groups of Poaceae,the height,coverage,aboveground biomassand belowground biomass of artificial grassland were higher than that of Cyperaceae,Leguminosae and weeds,and weeds in CK plots were higher than other economic groups.The dominant species and associated species of artificial grassland in each period were Elymus nutans and Poa crymophila,and their important values increased gradually with the increase of establishment years;the species diversity index of all economic groups showed a fluctuating and rising trend;the Shannon Wiener index and evenness index of artificial grassland planted for 3 years were the lowest,which were 0.66 and 0.48 respectively,and it was the highest for 21 years.In the NMDS analysis of plants,there was no overlap between the artificial grassland for 24 years,21 years and 12 years and CK plot,and their vegetation communities were very different.The results showed that the community diversity index of black soil land artificial grassland planted for 21 years was significantly higher than that of artificial grassland for other years,and the similarity with degraded black soil land grassland was the smallest,and the community composition was relatively stable.