Effect Of Livestock Dung Addition On Vegetation And Soil Characteristics In Alpine Grasslands

The interaction between Tibetan livestock and alpine grasslands is an important scientific problem of alpine grazing ecosystem management in the Tibetan plateau.Livestock excreta contains a large amount of NPK and mineral nutrients,and its deposition is similar to nutrient addition or soil fertilization.There are 13 million yaks and 30 million Tibetan sheep in Qinghai Tibet plateau,which excreta is large and widely distributed,and its role in alpine grassland ecosystem cannot be ignored.As one of the main forms of excreta,livestock dung has the characteristics of long retention time and slow decomposition,which plays a key role in maintaining productivity and restoring degraded grasslands in alpine grasslands.Previous studies of livestock dung on alpine grasslands has focused on:Livestock dung seed bank and interaction between livestock dung and vegetation and the temporal and spatial effects on vegetation from yak dung suffocation and fertilization,the research on the similarities and differences of the effects of livestock dung addition on vegetation and the effect of the dung addition form on alpine grasslands is relatively lacking.We studies that added yak dung different form(broken or not)and quantity(0,10,20 and 30 gN/m~2)on alpine meadow,and added different livestock dung(yak dung,Tibetan sheep dung adding gN10/m~2)and ureag(N10/m~2)on degraded alpine steppe soils and grass characteristics,and recovery efficiency,determine the best yak dung addition form and quantity on alpine meadow and the way of degraded alpine grasslands restoration of suitable kinds dung added.The main results are as following:The fertilization of yak dung effect of on meadow was broken>not broken,the grass content of N and P increased by 1.1-1.7 times and 1.1 times,the addition of not broken yak dung significantly reduced the grasslands vegetation coverage;with the increase content N of the yak dung,broken yak dung was conducive to the growth of grasslands vegetation,the suffocation effect of non broken yak dung on grasslands vegetation increased,and the addition of non broken yak dung in the second year had weak fertilization effect.Added yak dung,Tibetan sheep dung and urea increased the grass height by about 1.2 times,1.4 times and 1.6 times,and the aboveground biomass by about 1.1 times,1.4 times and 1.8 times,increased the grass biomass by 56.1%-74.5%,57.9%-72.5%and 59.5%-70.6%in the first to third year,and maintained the high grass biomass ratio in the three years.The addition of livestock dung increased the important value of grass and the number of plant species,increased the Shannon winer diversity index of community,decreased the Simpson dominance index of community,and increased the NP content of grass and the organic matter content of soil,the positive effect on the NP and the organic matter of soil lasted for more than two years,but the effect on the N of grass was lagging behind the urea.With the continuous time of nutrient addition,the frequency histogram of plant species Raunkiaer in alpine grassland community gradually showed an inverse J,the community tended to be stable,and the degraded alpine grassland gradually recovered;the recovery effect was Tibetan sheep dung and urea>yak dung>control.In summary,the suitable way of add yak dung in alpine meadow is broken,and the more N is added,the more obvious the effect is;The yak dung and tibetan sheep dung addition can improve soils and grass nutrients,enhance community stability and positive succession,which can be used as one of management and restoration measures for the restoration of degraded alpine grasslands.