青海共和盆地沙柳(Salix psammophila)和乌柳(Salix cheilophila)的水分利用过程

Water Use Process of Salix psammophila and Salix cheilophilain Gonghe Basin,Qinghai Province

利用稳定氢、氧同位素技术研究了青海共和盆地沙柳(Salix psammophila)和乌柳(Salix cheilophila)的水分来源,利用稳定碳同位素技术研究了它们的长期水分利用效率。沙柳春季同时利用10~150cm土壤水分和地下水,夏季主要利用10~25cm浅层土壤水分和地下水,秋季主要利用50~150cm深层土壤水分和地下水。乌柳春季主要利用10~25cm浅层土壤水分和地下水,夏季同时利用10~200cm土壤水分和地下水,秋季主要利用100~200cm深层土壤水分。沙柳和乌柳能够根据不同水源的可利用性,在不同季节选择利用不同深度的土壤水分或者地下水。它们之间存在一定程度的水分竞争。叶片δ^(13) C值表明春季干旱时两树种的长期水分利用效率较高。沙柳的长期水分利用效率高于乌柳,可能更适应共和盆地的半干旱气候。

Water source of Salix psammophila and Saline cheilophila in Gonghe Basin was studied by stable hydrogen and oxygen isotope, and their long term water use efficiency was studied by stable carbon isotope. The results showed S. psammophila evenly used 10--150 cm soil water and ground water in spring, main- ly used shallow soil water （10--25 cm） and ground water in summer, and mainly used deep soil water （50-- 150 cm） and ground water in autumn. Meanwhile, S. cheilophila mainly used shallow soil water （10--25 cm） and ground water in spring, evenly used 10--200 cm soil water and ground water in summer, and main- ly used deep soil water （100--200 cm） in autumn. Therefore, S. psammophila and S. cheilophila select- ed different water source to use depend on their availability in different seasons. There was a competition for water between two Salix shrubs. Their long term water use efficiency indicated by leaf carbon isotope decreased in drought spring. The long term water use efficiency of S. psammophila indicated by leaf δ13C was higher than S. cheilophila in different season, which mean the former might have more adaptability in Gonghe Basin with semiarid climate.