中国北方农牧交错带土地沙化区典型植物的雨季水分来源

中国北方农牧交错带是中东部地区重要的生态安全屏障, 由于其系统结构脆弱、生态环境问题多发、土地沙化严重, 开展生态修复工作显得十分重要。植物-土壤水分关系作为土地沙化区生态水文过程的重要组成部分, 研究二者的转化过程对于了解植物吸水模式、确定生态修复的首选植物种非常关键。以河北省张家口市康保县北部为例, 基于雨季的大气降水、地下水、土壤水和植物水的氢氧同位素特征, 分析了主要植物的吸水层位、生态位宽度和水分竞争关系。结果表明, 柠条以吸收80~100 cm深度土壤水为主, 吸水比例最大可达87.7%, 油菜花以吸收0~20 cm深度土壤水为主, 吸水比例最大可达82.3%, 狼针的吸水层位与土壤含水率有关, 在含水率较高的深度吸水比例更大, 栉叶蒿的吸水深度较为均衡, 各植物种的生态位宽度均较大, 但部分植物间存在较强的水分竞争关系。本研究为中国北方农牧交错带土地沙化区的植物水源来源识别和生态修复提供了科学依据。 

Water sources of typical plants during the rainy season in desertification areas of the agro-pastoral ecotone in northern China

The agro-pastoral ecotone in northern China is an important ecological security barrier for central and eastern China. Ecological restoration in this zone is very important due to its fragile ecosystem structure, frequent ecological and environmental problems, and severe land desertification. The plant-soil water relationship is essential to ecological and hydrological processes in land desertification areas. Studying the water conversion process between plants and soil is of great importance for understanding the water absorption patterns of plants and determining the preferred plant species for ecological restoration. Taking northern Kangbao County, Zhangjiakou City, Hebei Province as the study area, this study analyzed the water uptake layer, ecological niche width, and water competition of typical plants based on the hydrogen and oxygen isotopic characteristics of rainfall, groundwater, soil water, and xylem water during the rainy season, were analyzed. The results showed that Caragana korshinskii mainly absorbed soil water at a depth of 80-100 cm, with a maximum water uptake rate of 87.7%, while Brassica campestris mainly absorbed soil water at a depth of 0-20 cm, with a maximum water uptake rate of 82.3%. The water absorption layer of Stipa baicalensis was related to the soil moisture content, and the depth of water absorption of Neopallasia pectinata was more balanced. The ecological niche of each plant species is relatively wide, but there is intense water competition among some plants. This study provides a scientific basis for identifying plant water sources and ecological restoration in desertification areas of the agro-pastoral ecotone in northern China.