Study On Typical Vegetation Characteristics In Micangshan National Nature Reserve Of Shaanxi

The Micangshan National Nature Reserve of Shaanxi is located in the middle part of Micangshan.It is situated in the transitional zone between the warm temperate zone and the northern subtropical flora.The vegetation resources are abundant.Taking the Micangshan Nature Reserve of Shaanxi as the research area,the transect line,the sample and the typical sample plots method were used to investigate the vegetation characteristics of the main forest vegetation types and distribution,community structure,species diversity and dominant population spatial distribution of Abies fargesii and interspecific association of Quercus aliena var.acutiserrata secondary forest community.The characteristics of vegetation are investigated and explored to improve the effectiveness and immediacy of the protection of natural vegetation.It provides scientific basis and theoretical basis for effective protection and sustainable development of natural vegetation in the Micangshan Nature Reserve.The main results are as follows:(1)Based on the survey data of the vegetation,the classification system of natural vegetation in Micangshan Nature Reserve of Shaanxi is established in combination with the classification principle of “Chinese Vegetation”and the satellite remote sensing map,which includes 5 vegetation types,including coniferous forest,broad-leaved forest,shrub and shrub grass,meadow and halophytic marsh,14 vegetation types and 47 groups.From the perspective of the community,the characteristics and distribution of vegetation in Shaanxi Mi Cangshan reserve were analyzed.The largest area is deciduous broad-leaved forest,followed by coniferous and broad-leaved mixed forest.The area also has a large area of rare plant communities such as Cercidiphyllum japonicum,Taxus wallichiana var.chinensis and Emmenopterys henryi.(2)Influenced by environmental factors such as altitude,topography,soil,water and heat,and the interference of human activities,the natural vegetation in the protected area is distributed across the zone in a horizontal direction.In terms of horizontal distribution,it is generally divided into 4 areas: Longchi,Nanping,Hexi,and Loufang.Each area has its typical vegetation type.However,due to the flatness of the Long chi and the Loufang,and the large population distribution,the human disturbance is relatively large.The relative height of the protected area is large,and the vegetation in the area has obvious vertical distribution pattern.From high to low altitude,it is divided into 3 vegetation belts,which are deciduous broad-leaved forest,mountain coniferous broad-leaved mixed forest and low mountain forest and shrub.However,low mountain forest and shrub belt are lower in altitude,and are seriously disturbed by human beings.(3)The natural forest community of Abies fargesii in high altitude,the important value of Abies fargesii is as high as 59.14%,which was the constructive species.However,the number of young seedlings with the breast diameter less than 2.5 cm(diameter grade I)is seriously insufficient and the population structure is declining.There were obvious differences among species diversity in all layers of the Abies fargesii community,and the species richness index,diversity index,evenness index and dominance index of herb layer were higher than that of tree layer and shrub layer.Spatial distribution analysis of population showed that the variance mean ratio of Abies fargesii was 16.95,and the clump intensity was 2.50,which belonged to the type of cluster distribution.There were also 5 dominant species in tree layer,4dominant species in shrub layer and 10 dominant species in herb layer obeyed the cluster distribution,while a few dominant species were uniformly or randomly distributed.Although the plant species of the natural Abies fargesii community are abundant,the canopy density is high,but it is not conducive to the natural regeneration of young seedlings and the growth of saplings,and the community has been in the late succession.(4)The representative of typical deciduous broad-leaved forest,the Quercus aliena var.acutiserrata secondary forest community showed a significant positive correlation between the main tree species.Among them,52 pairs showed positive associations,and 39 pairs showed negative associations.The positive-negative relationship ratio is about 1:1,which indicates that the dominant species of Quercus aliena var.acutiserrata occupies the most advantageous position in the secondary forest community,and the degree of competition or dependence on the environmental resources is weakened,and the dominant species of the population are mostly in a stable state,which can resist the interference of the external environment.