Effects Of Grazing Cervus Elaphus Kansuensis And Bos Grunniens+ Ovis Aries On Vegetation And Soil Of Salix Cupularis Shrubland In Eastern Qilian Mountains

Alpine shrub grassland plays an important role in regional ecosystem stability,water and soil conservation and climate regulation,and are also a grazing ground for Tibetan livestock and a habitat for wild animals.Grazing is one of the most important utilization methods of shrub grassland,but there were few studies on the effects of long-term grazing of different livestock on the vegetation – litters – soil system of alpine shrub grassland in the past,and thus the similarities and differences of the effects of long-term grazing of Gansu wapiti and Tibetan livestock on the vegetation – litters – soil system of shrub grassland and their change rules are not clear.Therefore,in the Tianzhu Jinqianghe area of the Eastern Qilian Mountains.It has herders grazing continuously for 33 years of Salix cupularis as the constructive species,Potentilla parvifolia and Spiraea alpina as the companion species of shrub grassland as the research objects,the effects of grazing Gansu wapiti(Cervus elaphus kansuensis)and yak(Bos grunniens)+Tibetan sheep(Ovis aries)livestock on the vegetation – litters – soil system of a thicket grassland were compared and analysed This study will provide support for the rational use and sustainable development of alpine shrub grassland,and provide an important scientific basis for achieving the harmonious symbiosis between shrubs and herbs,improving the production capacity of grass and grazing,promoting the balanced development of grass and livestock,and maintaining ecological balance.The main results are as follows:The response of shrub height,crown width,biomass and coverage of the grazing Gansu wapiti plot were lower than those in the grazing yak and Tibetan sheep plot(P<0.05),which were 53.36%,67.54%,37.21% and 52.45% lower,respectively;The carbon storage of shrubs,the herbaceous carbon storage under and between shrubs were 14.99%,12.10%and 1.45% lower in Gansu wapiti plot < in yak and Tibetan sheep plot,respectively;The coverage and biomass of the herb communities were 4.34% and 74.84% larger in Gansu wapiti plot > in yak and Tibetan sheep plot,respectively;the nutrient content of the herbaceous plants also were as followers: Gansu wapiti plot > yak and Tibetan sheep plot.Among them,the content of soluble sugar,neutral detergent fiber and acid detergent fiber were significantly different(P<0.05),which were 46.31%,12.13% and 6.53% higher,respectively.However,the relative feeding value and the digestibility of herb plants were lower than the grazing yak and Tibetan sheep plot(P<0.05).Among them,the relative feeding value of herbs in the grazing Gansu wapiti plot was 13.34% lower than that in the grazing yak and Tibetan sheep plot.2.The total thickness,total storage,maximum water holding capacity,maximum water holding rate,maximum storage capacity and effective storage capacity of litter in alpine shrub grassland were as follows: Gansu wapiti plot < yak and Tibetan sheep plot(P<0.05),which were 19.83%,57.69%,48.46%,32.98%,62.89% and 70.06% lower,respectively.3.The soil respiration rate of the grazing Gansu wapiti plot was lower than that of the yak and Tibetan sheep plot,while the soil respiration rate under the shrub was higher than that of the grazing yak and Tibetan sheep plot;The soil moisture content of the shallow layer(0～40 cm)under and between the shrubs in the grazing Gansu wapiti plot was significantly higher than that of the yak and Tibetan sheep grazing plots,while the depth(40～100 cm)of the soil was the opposite;the bulk density of the 0～30 cm soil layer between the shrub clumps was as follows: Grazing yak and Tibetan sheep plot > grazing Gansu wapiti plot,the opposite was observed under shrubs;The soil initial infiltration and steady infiltration rate,organic matter,total phosphorus,total potassium,available nitrogen and available potassium content in the grazing Gansu wapiti plot were higher than those in the grazing yak and Tibetan sheep plot.4.The diversity and richness of the bacterial community among shrubs in the grazing Gansu wapiti plot and the richness index of the fungal community under the shrubs were lower than those in the grazing yak and Tibetan sheep plot.The relative abundances of saprophytic fungi and bacterial metabolism between shrubs and under shrubs were higher than that of the grazing yak and Tibetan sheep plot,And the relative abundances of arbuscular mycorrhizal fungi,animal parasites and human-related infectious disease bacteria were lower than those of the grazing yak and Tibetan sheep plot.In summary,long-term grazing of Gansu wapiti can effectively inhibit the expansion of Salix cupularis + Potentilla parvifolia + Spiraea alpina shrubs,facilitate the growth of herbaceous plants and improve herbaceous quality;it also improves the soil moisture and capacity of the shallow layer of shrub grassland and increases the nutrient content of the soil,but not good for shrub growth.Yak and Tibetan sheep grazing helps to improve water retention and soil conservation in alpine shrub grassland,protects soil microbial diversity,and promotes the expansion of Salix cupularis + Potentilla parvifolia + Spiraea alpina shrubs,but not good for herb growth.