The Responses Of Stipa Baicalensis To Salt-alkali Stress And Clipping

Stipa baicalensis is one of constructive species in Songnen Plain, has been seriouslydisrupted due mainly to overgrazing and land uses change. Now we can only see large areasof Leymus chinensis grassland. In this region, saline-alkali soil concentrates and overgrazinghave been major threats to the grassland. There are a number of studies on tolerances ofLeymus chinensis to salt stress and grazing. However, the responses of Stipa baicalensis tothose stresses have been rarely reported. Especially, to our best knowledge, there is no dataabout the responses of Stipa baicalensis in situ experiments. Therefore, this study will helpus better understanding of the response mechanisms of plant to salt stress and grazing,which has important ecological significance and economic value.A two factorial experiment was conducted in the natural field with the addition ofmixed salt-alkali solution (Nail: NaHCO3: Na2CO3=1:1:1) and clipping (removal60%ofaboveground biomass), each treatment has three repetitions. The aboveground biomass (AB)and belowground biomass (BB), plant density and height, photosynthetic and physiologicalparameters were measured. Our results indicate that moderate salinity stress increase heightand tillers. Salt tress significantly reduced photosynthesis under clipping, leading to the dropof AB, the value of BB is less affected by the two stresses. The maximum accumulation ofNa+occurred in shoot. Compared with no salt addition, the Na+content of root was higher,and clipping significantly enhanced the ability of salt stress to increase Na+concentration.The salinity treatment significantly reduced K+content of root, however, the value of K+showed an upward trend under clipping condition. The ratio of K+/Na+in shoot increasedwith salinity treatment, whereas it significantly reduced in the root. There is no anionsaccumulation within Stipa baicalensis with the exception of Cl-. In addition, clippingaccelerated the consumption of soluble carbohydrates. The content of proline of shoot andsoluble sugar of root was significantly reduced by clipping and salt-alkali stress. Overall,changes of these parameters show that Stipa baicalensis is not a grass to resist the grazingand salt stress. Our results suggest sustainable management is an effective way to restoreStipa baicalensis community, such as complete exclosure and rotational grazing, to achieverational utilization of grassland.