Effects Of Different Disturbance Modes On Grassland Ecological Characteristics ——A Case Study Of Altai

In this study,the effects of different disturbance modes on grassland ecolo gical characteristics in Altay were taken as the research object.Based on the monitoring data for many years,the changes of grassland vegetation ecological characteristics under different grazing years and cutting disturbances were analyzed.Combined with the chang es of environmental factors,the reasons for the differences in vegetation response were d iscussed,so as to provide the basis for scientific protection and rational utilization of gra ssland resources.The main results are as follows :（1）It was found that the average height,coverage and biomass of grassland in spring and autumn pastures and winter pastures were significantly improved after grazing prohi bition.When the grazing prohibition period was 2 years,the average height of grassland in spring and autumn pasture and winter pasture in the study area reached the highest,13 cm and 19.33 cm,respectively.However,with the extension of grazing prohibition ti me,some indexes such as average height,coverage and biomass showed fluctuation char acteristics,showing a downward trend on the whole,and only the coverage of spring an d autumn pasture showed an upward trend.The reason is that the implementation of gra zing prohibition measures makes the herbaceous plants have a complete growth cycle and promotes the growth of one-year-old herbaceous plants.Therefore,grazing prohibition ca n be used as a measure for grassland protection and restoration,but long-term grazing pr ohibition is not conducive to its growth and development,and it is necessary to master t he principle of moderate grazing prohibition.（2）The effect of fenced grazing prohibition on biodiversity in spring and autumn pas tures and winter pastures is obvious.The Shannon-Wiener diversity index of spring and autumn pasture reached the maximum of 1.49 after 7 years of grazing prohibition.Simps on diversity index,Pielou evenness index and Margalef richness index reached the maxi mum at 1 year of grazing prohibition,which were 1.00,1.23 and 1.64,respectively.The winter pasture showed an increasing-decreasing-increasing trend,and the Shannon-Wiener diversity index,Simpson diversity index,Pielou evenness index and Margalef richness i ndex reached the maximum values of 0.18,0.88,1.26 and 1.80,respectively,after two y ears of grazing prohibition.Therefore,the early implementation of grazing prohibition me asures is conducive to the increase of plant diversity.（3）Through analysis,the ecological characteristics of reed communities after annual mowing,no mowing and three-year mowing were significantly different.For example,the plant height significantly increased by 72.18% and 55.84%（P<0.05）,the plant diameter s ignificantly increased by 50.00% and 32.91%（P<0.05）,the Shannon-Wiener diversity inde x significantly increased by 150.23% and 61.03%（P<0.05）,and the Simpson diversity ind ex significantly increased by 105.77% and 45.58%（P<0.05）,indicating that the reed com munity was a constructive species of meadow in the salinization lowland.Cutting reed c ommunity is a means of protection.（4）According to the results of field surveys and herdsmen ’ s visits,the average gra ssland area per household in Altay decreased year by year from 1984 to 2018,from 973.13 ha / household to 360.42 ha / household.In addition,the number of large and small animals increased by 7 times and 2.3 times respectively during the study period,which led to serious degradation of grassland in Altay,and effective protection and measures were needed.（5）According to the study on the relationship between environmental factors and gras sland ecological characteristics,the factors that affect grassland biomass are not only ove rgrazing,but also the early regreening period of plants,climate drought,changes in soil moisture and p H,and long-term grazing prohibition.This is the main reason for the fluc tuation of vegetation height,coverage and biomass.However,at the same time of protect ion and restoration,the extension of grazing prohibition years will reduce grassland diver sity and ecological degradation.Therefore,it is necessary to carry out appropriate and ti mely grazing prohibition measures and effective protection measures such as cutting and fire disturbance.