半干旱区露天矿排土场不同植物水分利用策略的季节变化

Seasonal Variation in Water Use Strategies of Different Plants in an Open-pit Mine Dump Site in Semi-arid Area

[目的]探究旱雨两季不同植被配置模式下苜蓿与沙棘的水分来源,为矿区植被恢复提供理论依据。[方法]以内蒙古自治区鄂尔多斯市满来梁煤矿排土场平台为研究区,采用稳定同位素技术,采集研究区内3种植被配置模式下植物木质部样品、土壤样品、降水样品,分析其氢氧稳定同位素组成。[结果]①随着雨季的来临各样地土壤含水率均呈现增大的趋势,纯沙棘地由旱季的6.56%增长至9.88%,纯苜蓿地由7.94%增长至9.15%,混交地由9.4%增长至15.45%。②旱季不同植被配置模式下苜蓿与沙棘主要利用80-100 cm土壤水作为其水分来源。而雨季随着降水对土壤水的补充,土壤含水率增大,各类植被吸水深度发生上移,主要集中于20-60 cm处。[结论]植被不同配置模式下苜蓿与沙棘在旱雨两季水分来源大不相同,旱季二者主要集中于深层土壤,雨季吸水深度上移且吸水范围增加。雨季混交情况下沙棘为避免资源竞争会选择深层土壤水作为其主要水分来源。

[Objective]The water sources of alfalfa and seabuckthorn under different vegetation allocation patterns in drought and rainy seasons were studied to provide a theoretical basis for vegetation restoration in mining areas.[Methods]The platform of the dumping site of Manlailiang coal mine in Ordos City,Inner Monglia Autonomous Region was taken as the research area.The stable isotope technique was used to collect plant xylem samples,soil samples,and precipitation samples under three vegetation configuration modes in the study area,and the hydrogen and oxygen stable isotope compositions were analyzed.[Results]①With the advent of the rainy season,the soil moisture content of all plots showed an increasing trend.The pure seabuckthorn land increased from 6.56%in the dry season to 9.88%,the pure alfalfa land increased from 7.94%to 9.15%,and the mixed land increased from 9.4%to 15.45%.②Alfalfa and seabuckthorn mainly used 80-100 cm soil water as their water source under different vegetation configuration modes in the dry season.In the rainy season,with the supplement of rainfall to soil water,the soil moisture content increased,and the water absorption depth of various types of vegetation moved up,mainly concentrated at 20-60 cm.[Conclusion]The water sources of alfalfa and seabuckthorn were very different in the dry and rainy seasons under different vegetation configuration modes.In the dry season it was mainly concentrated in deep soil,and the water absorption depth moved up and the water absorption range increased in the rainy season.To avoid resource competition,seabuckthorn will choose deep soil water as its main water source under the mixed condition in the rainy season.