干涸盐湖地下水和土壤化学属性对自然植被分布的控制作用

我国西北地区湖泊萎缩、干涸,大面积裸露湖床成为化学粉尘的释放源。湖床植被能有效抑制粉尘排放,提高干涸湖床植被覆盖度成为生态治理的重要举措之一。本研究以内蒙古北部边缘典型现代干涸盐湖--巴拉嘎斯湖为研究区,通过野外调查,样带选择,实地采样分析和实验室统计分析,研究了干涸湖床地下水及土壤化学属性对湖区自然植被分布的控制作用。结果表明:在地下水和土壤化学属性影响下,湖区植被从干涸湖床至湖滨依次呈现芦苇群落、盐爪爪群落、芨芨草群落、红砂群落和小针茅群落的环状分布。湖区自然植被分布主要受地下水水位、地下水总溶解性固体(TDS)与土壤有效磷含量的控制。地下水埋深由湖床至湖滨逐渐增加,地下水TDS逐渐减小,当地下水埋深为4 m左右且TDS较低(<10 g·L^-1)时,植被群落呈现最大生物量及最大覆盖度。土壤有效磷对植被分布影响最大,其次是土壤中SO4^2-。当土壤含盐量能满足原生自然植被正常生存的条件时,地下水与土壤有效磷含量应是人工恢复植被优先考虑的因素。

Effects of Groundwater and Soil Chemical Properties on Distribution of Natural Vegetation around 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 in the 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.The spatial distribution of natural vegetation around the playa was mainly affected by groundwater level,total dissolved solids(TDS)and soil available phosphorus content.The groundwater depth increased gradually but the groundwater TDS decreased from the lake bed to the lakeside.The biomass and coverage of the vegetation was maximal when the groundwater depth was about 4 m and the TDS was lower than 10 g·L^-1.The effect of soil available phosphorus content on the spatial distribution of natural vegetation was the highest,and then that of soil SO4^2-.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.