关键词: 科尔沁沙地, 植被恢复, 群落组成, 植物多样性

Abstract:

Mobile dune， fixed dune and sandy grassland are the products of desertification in Horqin Sandy Land. Vegetation restoration and reconstruction are the main measures for controlling the sand in this area. Understanding the community composition and plant diversity evolution characteristics in the process of vegetation restoration is beneficial for the restoration of sandy vegetation and ecological reconstruction. Based on the long-term survey results of plant communities in the process of vegetation restoration on mobile dune， fixed dune and sandy grassland in Horqin Sandy Land for the past 15 consecutive years， this study analyzed the characteristics of species composition and plant diversity in the process of vegetation restoration of three different types of sandy land， and compared the important values of plant species in 2005 and 2019. The results showed that： （1） In the past 15 years， the plant species richness and aboveground biomass of mobile dune were lower than fixed dune and sandy grassland， and the interannual fluctuations of aboveground biomass were small；Linear regression found that the community coverage showed a significant increasing trend （P<0.05）， and the relative coverage， relative biomass and important value of shrubs showed a significant decreasing trend （P<0.05）；The relative coverage， relative biomass and importance value of annual herbs were significantly higher than perennial herbs and shrubs；Annual herbs were significantly negatively correlated with perennial herbs and shrubs （P<0.01）， and the correlation coefficients respectively were -0.711 and -0.8302.After 15 years of community succession， annual herbs （Inula britanica，Agriophyllum squarrosum， Inula salsoloides and Corispermum hyssopifolium）still were the dominant species；annual herbs （Digitaria sanguinalis） and shrubs （Artemisia halodendron） were successively degraded. （2） Through linear regression， it was found that the relative coverage， relative biomass， and importance values of annual herbs in fixed dunes showed a significant increase （P<0.05）， and relative abundance and importance values were significantly higher than perennial herbs and shrubs； The relative coverage， relative abundance， relative biomass and important value of shrubs all showed a significant decreasing trend （P<0.05）； Annual herbs were significantly negatively correlated with perennial herbs and shrub （P<0.01）， and the correlation coefficients respectively are -0.569 and -0.892；The number of species had increased by 200% compared to the mobile dune.After 15 years of community succession， the succession of Artemisia halodendron， Euphorbia humifusa and Digitaria sanguinalis had degraded， while Aristida adscensionis and Echinops gmelini had been new dominant species. The stability of the plant community had relatively small inter-annual fluctuations， and the community stability was relatively stable. （3） Through linear regression analysis， it was found that the relative coverage， relative abundance and importance of annual herbs in sandy grassland showed a significant increasing trend （P<0.05）， and there was a significant negative correlation with perennial herbs （P<0.01）. The coefficient was -0.967； After 15 years of community succession， annual herbs （Chenopodium acuminatum and Setaria viridis） and perennial herbs （Artemisia scoparia and Phragmites australis） were the dominant species. Agropyron mongolicum was degraded， the sandy grassland had been degraded. The inter-annual variation of plant community stability was relatively large， and the community structure had not stabilized. In summary， in the past 15 years， the vegetation restoration of mobile dunes in the Horqin Sandy Land was very effective. The stability of the fixed dune community was relatively stable， and the community structure of the sandy grassland was not stabilized； annual herbaceous plants had the main advantage in vegetation restoration.

Key words: Horqin Sandy Land, vegetation recovery, species composition, plant diversity