辽西半干旱区不同林龄大扁杏人工林的水分利用特征

Water Use Characteristics of Different Ages of Prunus armeniaca Plantations in Semi-arid Region of Western Liaoning Province

利用稳定氧同位素技术,测定辽西地区不同林龄(5,11,17a)大扁杏枝条木质部水分、土壤水、降雨的雨水和井水的δ18 O值,结合其根系分布特征,分析不同林龄大扁杏人工林主要利用的水分来源;测定叶片δ13C值,分析不同林龄大扁杏人工林的水分利用效率。结果表明,大扁杏人工林利用土壤水的深度不同,5年和11年生大扁杏人工林主要利用0—30cm深度的土壤水,与其吸水根(d≤1mm)分布的土层深度一致,二者输导根分布在20—50cm土层深度;17年生大扁杏人工林主要利用0—20cm和50—70cm深度的土壤水,其吸收根分布在0—30cm土层深度,输导根分布在10—70cm土层深度;δ18 O值表明,3个林龄大扁杏人工林利用的土壤水均来自降雨的雨水和地下水;5年生大扁杏林的水分利用效率为-24.1‰,显著高于11年生和17年生大扁杏林(P<0.05)。大扁杏人工林在不同生长发育阶段因其根系分布的差异而具有不同的水分利用特征,有助于其更好地适应辽西地区的半干旱环境。

Prunus armeniacais a main shrub species of ecological and economic plantation in semi-arid area in western Liaoning Province.A water use strategy,including the main water source which a plant species utilizes and water use efficiency（WUE）,plays an important role in plant survival and growth.Understanding the water use strategies of a shrub plantation can be used to evaluate the sustainability and long-term stability of the plantation.Stable oxygen isotope ratios（δ18 O）of water in rain,well,branch xylem,and in soil at different depth of 5,11 and 17-year-old P.armeniaca plantation were tested to trace the main water source of P.armeniaca.Root systems were investigated to determine the depth of the main distribution.Leaf carbon isotope ratios（δ13 C）were used to evaluate the long-term WUE of P.armeniaca plantation.The results showed that 5and 11-year-old P.armeniacaplantations mainly derived soil water from the 0—30cm layer,which were coincident with the distribution of their fine roots.Conductive root systems of 5and 11-year-old P.armeniaca plantations were distributed primarily in the 20—50cm layer.17-year-old P.armeniaca plantations derived water mainly from the 0—20cm and 50—70cm layers,with their fine root and conductive root system being distributed primarily in the 0—30cm and 10—70cm layer,respectively.Theδ18 O values indicated that these sources of soil water were recharged by rainfall and groundwater.The long-term WUE of5-year-old plantation（-24.1‰）was greater than those of the 11 and 17-year-old plantations（P〈0.05）.The water use strategies suggested that P.armeniaca plantation can adapt to a semi-arid environment of western Liaoning Province by changing its water use strategy over time.