Research On Vegetation Restoration Measures And Rehabilitation Effect In Serious Sand-damaged Areas Along Qinghai-Tibet Railway

Vegetation is the main part of terrestrial ecosystem,and vegetation restoration is the basic measure and the most effective method to solve desertification land.Vegetation restoration can be divided into two parts:artificial vegetation and natural vegetation restoration.The vegetation restoration along the Qinghai-Tibet Railway mainly depends on artificial vegetation.Under the influence of artificial vegetation,vegetation restoration along the Qinghai-Tibet Railway can not only improve the physical and chemical properties of sandy soil,but also improve the safe operation of the railway.It plays an important role and has remarkable ecological and economic benefits.The Qinghai-Tibet Plateau,where the Qinghai-Tibet Railway passes,is the only unique ecosystem in the world.It has high altitude,thin air,cold climate,drought,difficult site,slow material circulation and energy conversion,sensitive and fragile ecological environment.Therefore,there are many difficulties in the process of vegetation restoration.In this paper,the sand-damaged section of Qinghai-Tibet Railway is taken as the research object,and the measures and effects of vegetation restoration along the railway are mainly studied in order to provide a theoretical basis for vegetation restoration in ecologically sensitive and fragile areas along the Qinghai-Tibet Railway.Seeds of four herbaceous species,i.e.,Onobrychis viciifolia?Medicago sativa?Elymus dahurieus and Festuca elata,were sown with dififerent mixing modes and different mixing rates in desertification area of Cuona Lake in Tibet.Some plant growth characteristics,such as biomass per area after the growth period were analyzed.The purpose of this paper is to find the suitable grass species and the best planting modes suitable for the grassland restoration in the desertification area of Cuona Lake.The results showed that:1)Effects of mixing modes on plant height and root length were not significant for two gramineous species,Elymus dahuricus and Festuca elata,however,were significant increase for two leguminous species,Onobrychis viciifolia and Medicago sativa;2)Mixeing modes significantly affected the biomass per area.with biomass of mixed sowing plants increasing with the decrease of leguminous plants proportion,biomass of the best modes were 151.27± 15.26 g/m2(E.dahuricus monoculture)and 144.05±7.13 g/m2(E.dahuricus+Festuca elata 5:5)for the first year and 832.13±124.71 g/m2(E.dahuricus monoculture)and 723.83±57.14 g/m2(E.dahuricus+Festuca elata 7:3)for the second year,3)Mixing modes of the two gramineous species showed high total coverage per area,with the maximum coverage of Elymus dahuricus+Festuca elata(5:5)being 87%in the first year and over 60%in the second year.4)Contribution of gramineous species to biomass per area in this experiment under alpine elimate was signifieant higher than that of leguminous species.Through the investigate of soil and vegetation under five different types of artificial restoration modes along the Xining to Golmud section of Qinghai-Tibet railway,the effects of artificial restoration modes on the plant diversity and properties of soil under plantation were analyzed.The results showed that the aboveground biomass and productivity of the plantation were different due to stand age and allocation.The highest productivity of plantation which Populus simonii-Tamatix chinensis was 1.92 t·hm-2·a-1,followed by plantation of Tamatix chinensis was 1.87 t·hm-2·a-.All modes have increased the diversity of plants under plantation,among them,there are eight species plants in the plantation of Hippophaer hamnoides-Caragana korshinskii,and ten species plants in the plantation of Tamatix chinensis,however,the dominant species are different in diffberent modes.Soil moisture content increased by all of the five restoration inodes.The effect of shrub plantation on improving soil alkalinity was better than others:in the plantation of Hippophaer hamnoides-Caragana korshinskii and Tamatix chinensis,the pH of surface soil(0-20 cm)decreased by 1.05 and 0.75 respectively.All of the five restoration modes increased the eontent of organic matter in soil and it showed a "surface accumulation"phenomenon from surface to deep.The organic matter in the plantation of Tamarix chinensis increased most obviously:the surface content of organic matter was 12 g·kg-1,which was nearly doubled compared with the content in bare land.This result provides a theoretical basis for combating desertification and the selection of vegetation restoration modes along the Qinghai-Tibet railway.