Health Evaluation Of Grazing Utilization Grassland Based On The Variation Of Established Species And Degraded Indicator Species

This study objected on Stipa breviflora desert grassland.We investigated and analyzed through field and indoor samples in 2019,to analyze quantitative characteristics,soil nutrients,community diversity of Stipa breviflora(the constructive species)and Convolvulus ammannii(the degenerative indicator species)under different grazing intensities.We estimated the grassland health VOR and CVOR comprehensive index evaluation,and fuzzy comprehensive evaluation based on the changes in the quantitative characteristics of two species combining with vegetation and soil factors.Aim to provide a theoretical basis of determining reasonable grazing intensity,and the selection of grassland health evaluating methods.The result shows that:(1)With the increase of grazing intensity,the populations of Stipa breviflora were decreased,while the populations of Silver Grey Convolvulus were increased.And the quantitative characteristics of Stipa breviflora were higher in May,June and October,while the quantitative characteristics of Silver Ash Convolvulus were higher in July and August.(2)The Margarlef index.Shannon-wiener index and Simpson dominance index of the community were higher in MG and also higner in July and August.(3)Grazing increased the content of soil nitrogen but decreased the content of soil phosphorus and potassium.With the grazing intensity increasing,the soil alkaline nitrogen content was increased and total potassium,rapid potassium,and rapid phosphorus content were decreased.(4)The grassland health evaluating results of the no grazing(CK),moderate grazing(MG)and severe grazing(HG)treatment were healthy,healthy and unhealthy using VOR,CVOR index model and fuzzy comprehensive evaluation methods.All the three methods can be used to evaluate the health of desert grasslands.(5)The comprehensive evaluation results show that the moderate grazing grassland was in healthy,and the suitable stocking rate was 1.92 sheep/hm2 during the growth season of Stipa breviflora desert grassland(May-October).