基于稳定同位素技术的黄河支流河岸植被水分来源解析

目的] 分析比较不同水分梯度下植物水的氢氧同位素特征，为黄河流域生态保护与防蚀控沙中适宜物种的筛选提供一定的理论基础。方法] 采用氢氧稳定同位素技术，基于HYSPLI4气团轨迹模型和贝叶斯混合模型MixSIAR，分析黄河主要支流—西柳沟河流河岸不同水分梯度下优势植物对潜在水源利用率，进而提出不同植物的水分利用策略。结果] 研究区在采样期间降水的水汽主要来源于西北季风输送和局地蒸发。在水分充足的河漫滩样地，植物以浅层土壤水（0—30 cm）为主要水源。距离河道较远的河谷阶地上，草本类植物主要利用浅层和中层土壤水（0—70 cm），灌木类和高大草本类植物转而吸收更深层的土壤水（70—100 cm），出现水文生态位分离的现象。结论] 当水分缺乏时，灌木类植物会因为吸水模式的优势具有更强的生存竞争力。灌木类植物是黄河流域生态保护与防蚀控沙的适宜物种。

Analysis on Water Sources of Riverbank Vegetation in Tributary of Yellow River Based on Stable Isotope Technique

Objective] The hydrogen and oxygen isotope characteristics of plant water under different water gradients were analyzed and compared in order to provide a theoretical basis for the selection of suitable species for ecological protection, erosion control, and sand control in the Yellow River basin.Methods] Using hydrogen and oxygen stable isotope technology, based on the HYSPLI4 air mass trajectory model and the Bayesian mixed model MixSIAR, the potential water utilization efficiency of dominant plants under different water gradients along the banks of a major tributary of the Yellow River, was analyzed, and water utilization strategies of different plants were then proposed.Results] The atmospheric vapor was mainly affected by the local evaporation air mass and northwest monsoonal transport during the sampling period. Shallow soil water (0-30 cm) was the main water source for plants in the floodplain. On terraces of the river valley, herbaceous plants mainly used shallow and middle soil water (0-70 cm), while shrubs and tall herbs used water from deeper soil layers (70-100 cm). The phenomenon of ecohydrologic niche separation between plants was apparent.Conclusion] When water is scarce, shrubs are more competitive because of their water use patterns. Shrubs are suitable species for ecological protection, erosion control, and sand control in the Yellow River basin.