Water-use characteristics of plants are important for vegetation restoration in shallow earth-rock mountain area. In this study, soil and plant samples of Platycladus orientalis and corn were collected after rainfall events in Yingwugou watershed of Dan River to analyze the signatures of oxygen isotopes and the response of water use patterns to precipitation using stable isotope technology. The results showed that there were different response characteristics of the soil water utilization to precipitation between P. orientalis and corn. The root of P. orientalis mainly used the soil moisture from 10-30 cm layer, while corn mainly used that in the depth of 0-20 cm. The water absorption depth (WAP) of P. orientalis root decreased from 20-30 cm to 10-20 cm, while that of corn altered from 10-20 cm to 0-20 cm, when precipitation decreased from 29 mm to 8 mm. The WAP of P. orientalis gradually changed from deep to shallow soil, while the main WAP of corn increased from 10-20 cm to 0-20 cm, whenprecipitation decreased. The response of P. orientalis and corn to precipitation was very obvious.
植物的水分利用特征对浅层土石山区的植被恢复具有重要意义.本研究利用稳定同位素技术,通过采集降雨后丹江鹦鹉沟小流域侧柏和玉米的植物样及其植物根系周围的土壤样品,分析其氧稳定同位素特征,研究土石山区侧柏和玉米两种不同植物的土壤水分利用方式对降雨的响应特征.结果表明: 侧柏和玉米的土壤水分利用方式对降雨存在不同的响应特征.侧柏根系主要利用10～30 cm土层的土壤水分,而玉米主要利用0～20 cm土层的土壤水分.降雨量由29 mm减少至8 mm时,侧柏根系的主要吸水深度由20～30 cm减小到10～20 cm,玉米根系的主要吸水深度由10～20 cm转换为0～20 cm.降雨减少时,侧柏根系吸水的主要深度均由深层土壤向浅层土壤移动,而玉米的主要吸水深度由10～20 cm增加为0～20 cm.侧柏和玉米根系的土壤水分利用方式对降雨的响应特征较为明显.
Keywords: oxygen isotope; returning cropland to forestland; rocky mountainous area; water source.