Study On Vegetation Community Characteristics And Edible Plant Nutrient Content Of Blue Sheep(Pseudois Nayaur) In Main Active Area Of Helan Mountain

Due to the continuous growth of the number of blue sheep in Helan Mountains,but uneven distribution,it has a great threat to the ecological balance of Helan Mountains.In order to maintain and enhance the coordination of the ecosystem in Helan Mountains,strengthen the protection and management of blue sheep,the characteristics of vegetation community and the nutrient content of edible plants of blue sheep in the main activity areas of Helan Mountains were studied,which provided scientific basis for the reasonable management and protection of blue sheep population,and had important ecological significance for the natural resource management and sustainable development of Helan Mountains.In this study,representative plant types were selected in Suyukou management station of Helan Mountains National Nature Reserve.With the elevation increasing,the order is desert steppe in 1100—1500m,mountain sparse forest steppe mainly composed of Amygdalus mongolica or Ulmus glaucescens in 1500—2000 m,mountain coniferous forest in 2000—2500 m and subalpine shrub meadow above 2500 m.In each activity area,5 herbaceous quadrats(1 m×1 m),5 shrub quadrats(10 m× 10 m)or 3 arbor quadrats(20 m×20 m)were set up.The species,height,coverage,frequency,abundance and aboveground biomass of plants were investigated by using the method of survey record.The crown width and Diameter at breast height of shrub and arbor plants were measured.Analysis of variance,multiple comparison and regression analysis were used to analyze the plant species,geographical components and diversity index;The main edible plant samples were collected for experiment at the same time of vegetation survey The nutrient content of the plant was determined in the laboratory,including plant crude ash,neutral detergent fiber,acid detergent fiber,crude fat and crude protein.The results show that:(1)A total of 92 species of 31 families,64 genera were recorded in the active area of blue sheep in Helan Mountains.Among them,there were 49 species of edible plants belonging to 30 genera,15 families.Gramineae has the largest number of species,followed by Rosaceae and Compositae.The geographical composition of the main active areas of the blue sheep in Helan Mountain is mainly temperate distribution,which is mainly North Temperate distribution,followed by North temperate and South Temperate disjuncted(Pan-Temperate),Old world temperate distribution,Temperate Asia distribution,etc.In the community structure,the species richness,Shannon Wiener diversity index and Simpson dominance index of herbaceous plants were higher than those of shrub layer,while the evenness index was lower than that of shrub layer.In research area of subalpine shrub meadow,the herbaceous species richness index,Simpson dominance index,Shannon-Wiener diversity index and Pielou evenness index were the highest,and the lowest were all belong to mountain coniferous forest.(2)Gramineous herbs and shrubs are rich in nutrients.The results showed that there was interaction between neutral detergent fiber,acid detergent fiber and crude fat in different growth stages and different research areas.The content of crude ash,neutral detergent fiber,acid detergent fiber and crude fat in dry season was higher than that in full season,while the content of crude protein in full season was higher than that in dry season.(3)The average environmental capacity of plant communities at different altitudes is about 6.50 sheep/km2.The results showed that with the increase of altitude,the environmental capacity increased first and then decreased.The area with the highest environmental capacity is the mountain sparse forest grassland dominated by Ulmus glaucescens between 1500-2000m,which is about 15.08 sheep/km2.It can be concluded that:(1)Gramineous plants are the main herbaceous plants,and Rosaceae plants are the main shrubs.The altitude gradient has a certain influence on the plant species diversity in the main activity areas of the blue sheep in Helan Mountain.The species diversity of herbaceous plants reaches the peak in the high altitude area,while the species diversity of shrub plants is the largest in the middle altitude area because of their light loving but not waterlogging tolerant characteristics.On the whole,the species diversity of herbaceous plants decreased first and then increased with the increase of altitude,while the species diversity of shrub plants increased first and then decreased with the increase of altitude.(2)According to the evaluation index of nutritive value,the nutritive value in full grass period is higher than that in dry grass period.The contents of neutral detergent fiber,acid detergent fiber and crude fat were related to different growth stages and different altitudes,while the differences of crude ash and crude protein in different growth stages were only related to altitudes.(3)The rapid growth of the number of blue sheep in Helan Mountain reduced the environmental capacity of the plant communities in the main activity areas of blue sheep.Therefore,it is suggested that different management and protection measures should be taken at different altitudes to prevent vegetation degradation and promote the healthy development of blue sheep population.