Distribution Patterns And Control Factors Of Vegetation In Playa

Lakes in northwest China are dramatically shrunk and even dried up.Large areas of exposed lake beds become as the sources of chemical dust.Promoting vegetation coverage is an effective way in suppressing dust emissions and regenerating ecosystem.In this study the Balhages playa,typical northern marginal zone of Inner Mongolia,was selected to examine the effects of groundwater and soil chemical properties on the spatial distribution of natural;vegetation based on the field survey,transect investigation,field sampling and laboratory analysis as well as statistical analysis.The results showed that,under the influence of groundwater and soil chemical properties,the communities of Phragmites australis,Kalidium foliatum,Achnatherum splendens,Reaumuria songarica and Stipa klemenzii were distributed in a ring shape from the dried lake-bed to the lakeside.And outward was the communities of Sympegma regelii which was distributed as plaque.The heterogeneity of community spatial pattern was obvious.The soil salinization of playa was relatively high,and the surface aggregation of salinity was strong,especially chloride.The spatial distribution of natural vegetation around the playa was mainly affected by groundwater and soil available phosphorus content.The groundwater depth increased gradually bur the total dissolved solids?TDS?decreased from the lake-bed to the lakeside.The biomass and coverage of the vegetation was maximal when the groundwater depth was suitable?about 4 m?and the TDS was relatively low(<10 g·L^-1).Soil salinity determines whether vegetation can survive normally.Soil salinity is too high?>1.5%?for vegetation to survive normally.And when vegetation grows normally,the effect of soil available phosphorus content on the spatial distribution of natural vegetation was the highest.When soil salt content is feasible for the survival of native natural vegetation,groundwater and soil available phosphorus content should be preferentially considered for artificial vegetation regeneration over playa.