Effects Of Dominant Shrub Populations On Neighboring Herbaceous Plants Under Different Stocking Rates In Desert Steppe

Shrubs encroachment will lead to changes in the structure and function of the grassland ecosystem.The study on the effects of the dominant shrub populations of desert steppe on neighbouring herbaceous plants under different grazing rates will help explain the co-evolutionary effects of different plants in the desert steppe.This paper focused on the interaction between 4 dominant species and their's neighbouring herbaceous plants in different stocking rates.The experiment uses a completely random block design with three blocks and each block with four stocking rate gradients.The stocking rates are 0(CK),0.91(LG),1.82(MG),and 2.71(HG)SE·ha-2·half year-1.Four dominant shrubs including Ceratoides latens,Artemisia frigida,Caragana microphylla,and Kochia prostrata were selected,and each shrub with 3 individual replications in each different stocking rate treatment plot,and labeled as 1,2,and 3,respectively.The quantitative characteristics of nerghbouring herbaceous to selected 4 dominant shrubs are tested within a radius of 50 cm around the each individual shrub.At the end of May each year,the species composition,coverage,density and height of all herbaceous plants were measured in eight fan-shaped quadrats with a radius of 50 cm surround to the selected shrubs,and then the No.2 shrub was removed from the ground,double checked No.2 shrub every half a month,once some new shoots occurrence,all would be removed again,for test the effects of shrub remove to the neighbouring herbaceous plant;at the end of August,the above-ground biomass of each species surrounding to the object shrub were measured.The main results are as follows:1.Wiht the increasing of the stocking rate,the density of the shrubs decreased siginificantly,but annuals and biannuals increased significantly at the same time;2.The surrounding herbacous plants increased significantly when the shrubs were removed in the desert steppe,which demonstrated that the shrubs had an inhibitory effect on the growth of the neighbouring herbacous plants.The above research results show that there is a competitive relationship between the shrubs and the neighboring herbaceous plants in the Stipa breviflora desert steppe in Inner Mongolia,named as there is a compensany effect among shrubs and neighboring herbaceous plants for the utilization to the external resources.And the increasing stocking rate has not exacerbated the shrubs encroachment in this type of grassland,in the contrast,incrassing the stocking rate reduced the shrub's ratio in the desert steppe,which demonstrated that grazing is one of the tools for the control of the ratio of shrubs and herbaceous plants.