Temporal And Spatial Charavteristics Of Grass Yield And Analysis Of Grass-livestock Balance In Xilingol League From 2000 To 2017

The analysis of spatial heterogeneity and temporal dynamic characteristics of grassland productivity at the regional scale;Study on the balance of grass and livestock.They are a basic work to explore ways to reduce the grazing pressure of natural grassland and restore and maintain the sustainable use of animal husbandry.This paper collects MODIS remote sensing satellite data,and grassland biomass dry weight data based on field measurements.Establish the inversion model of NDVI and grassland yield data in XilinGol League,and obtain grassland yield data of the whole league and each county,analysis of spatial heterogeneity and temporal dynamics of grass yield in growing season(April-September)of XilinGol League during 18 years(2000-2017).Regression analysis based on climate data.And analysis of spatial heterogeneity and temporal dynamics of grass livestock balance in XilinGol League based on grassland area and livestock loading data.The main conclusions are as follows:(1)The grassland yield of the whole showed a decreasing trend from northeast to southwest.The annual grass yield of the whole league ranged from the highest to the lowest in the order of northeast and southernmost,central and southwestern regions.The average grassland yield was 81.7(g/m~2)in 18 years.The average annual change rate was 11.1%,and the change amount was 9.1(g/m~2).In the growing season of forage,the lowest month of grassland yield in the whole league and counties was April,and the highest month was August.The monthly yield of grassland showed a single peak trend of increasing first and then decreasing.The highest growth rate of monthly yields in the league and the counties was in June,and the lowest growth rate was in September.It showed that the vegetation growth and forage production season have a stable synchronization of rain and heat.In XilinGol League,the annual grass yield was positively correlated with the annual rainfall and negatively correlated with the annual average temperature.The correlation between annual grass yield and annual rainfall was higher than that between annual average temperature.The overall performance of each county was that the correlation between monthly grass yield and monthly rainfall was higher than that between monthly average temperature.And the influence of precipitation and average temperature on grassland grass yield in last month is greater than that of this month.(2)During 2000-2017 in XilinGol League,the average livestock load at the end of June was 101.9(sheep unit/km~2)and 58.8(sheep unit/km~2)at the end of December.The annual livestock load of the League and counties at the end of December was more stable than that at the end of June.Taibus Banner and Duolun,located in the south,have higher livestock carrying capacity.The livestock carrying capacity of Erenhot,Sonid Right Banner,Sonid Left Banner,located in the southwest,was relatively low.The average ratio of livestock number at the end of the year to that at the middle of the year in the 18 years of the League was 57.82%.The ratio of livestock number at the end of the year to that at the middle of the year in all counties was higher than 54%.In the years with poor precipitation and low grass yield,one of the measures for herdsmen to cope with the shortage of forage was to increase the rate of sales at the end of the year.The balance of grass and livestock in the League was overloaded in January,February,March and December.The balance of grass and livestock was balanced from May to October.The balance rate of grass and livestock was 94.12%in April and 50%in November.The balance of grass and livestock in each county was overloaded from January to March.From June to September,most counties had a balanced grassland and livestock.Erenhot,Sonid Right Banner,Sonid Left Banner are located in the desert grassland area in the southwestern part of the League.They have less forage available for reserve in the growing season than other counties.Therefore,in addition to the rapid fattening of livestock in that year and the purchase of forage for basic livestock in the local overwintering breeding mode,it is necessary to further explore the development of quality animal husbandry through animal breeding improvement,and in the dry years of desertification grassland,in the dry season of winter and spring,and in the harvest season of forage and grain straw in the agro-pastoral ecotone,to explore an effective way to reduce the carrying capacity of livestock in natural grassland by forage trading or transfer fattening of livestock across regions.