太行山南麓3种常见灌木的水分利用特性

Water Use Strategies of Three Native Shrubs in the Southern Taihang Mountain

【目的】研究太行山南麓低丘山区乡土灌木的水分利用特性,为该区困难立地植被恢复的植被种类选择和群落演替管理提供理论依据。【方法】采用稳定碳同位素方法结合热扩散探针和土壤水分传感器,研究太行山南段南麓荆条、酸枣和扁担杆的叶片δ^(13)C值、树干液流和土壤含水量,分析3种灌木的水分利用特性差异及季节变化。【结果】2013年春旱和秋旱分别持续115天和2个月;荆条、酸枣和扁担杆生长季分别耗水42.32,13.23和96.17 mm,均在夏季较多,5和9月较少,扁担杆在各个时期的耗水量都高于荆条和酸枣;3种灌木叶片δ^(13)C值均表现为春季>秋季>夏季中后期,其中酸枣和荆条的δ^(13)C值高于扁担杆,且在秋旱时比后者提早1周升高δ^(13)C值,由于高δ^(13)C值意味着高水分利用效率,表明酸枣和荆条比扁担杆水分利用效率高,并对干旱响应敏感,能及早提高水分利用率;季节性干旱时,荆条的水分利用率更高,而酸枣能保持较高的组织含水量,保水力较强;扁担杆的枝条含水量在降雨后能迅速大幅升高。【结论】3种灌木的蒸腾耗水量和水分利用效率的季节变化规律类似,但水分利用策略存在种间差异。荆条和酸枣具有耗水少、水分利用效率高和深水源等抗旱节水的水分利用策略,可作为困难立地造林和植被恢复的先锋灌木引入。扁担杆则是高耗散、低水分利用效率和浅水源的水分利用策略,宜在荒山恢复中后期引入。

【Objective】The objectives of this study were to find out the water use strategies of native shrubsatthe southern foot of Taihang Mountain,and to providea theoretical guidance for species selection and community succession management for vegetation restoration.【Method】The stable carbon isotope technique,thermal dissipation probe(TDP)and soil humidity sensors were used to measure the leafδ^13C value,sap flow density and soil water contentin order to obtain the differences and seasonal variations of water use strategies among three native shrubs Vitex negundo var.heterophylla,Ziziphus jujuba var.spinosa and Grewia biloba.【Result】Seasonal droughts occurred during spring(115 days)and autumn(2 months)of the year 2013 in the study area.The water consumption of V.negundo,Z.jujuba var.spinosa and G.biloba in the growing season were 42.32,13.23 and 96.17 mm,respectively.The three shrubs all consumed more water in summer,and less water in May and September.G.biloba consumed more water than V.negundo and Z.jujuba var.spinosa did duringthe whole growingperiod.The leafδ^13C value of the three shrubs was the highest in spring,the nextin autumn,and the least in middle and later summer.The G.biloba had lower leafδ^13 Cvalue than V.negundo and Z.jujuba var.spinosa did,which suggests that G.biloba had a lower water use efficiency,as higher leafδ^13Cvalue indicates higher water use efficiency.The leafδ^13C value of V.negundo and Z.jujuba var.spinosa increased one week earlier than that of G.biloba during autumn drought event.The result indicates that the firsttwo shrubs were more sensitive to drought and can increase water use efficiency promptly when drought occurs.During seasonal drought period,the leafδ^13C value and water use efficiency in V.negundo were higher than in Z.jujuba var.spinosa,whereas Z.jujuba var.spinosa can maintain higher water content in both leaves and twigs,indicating a strong water retention capacity.The twig water content of G.biloba increased immediately with a great amount after rainfall event.【Conclusion】The water consumption and water use efficiency showed similar seasonal variation in the three shrubs.However,they had different water use strategies.The Z.jujuba var.spinosa and V.negundo consumed less water,with a higher water use efficiency,and water use from deep water source.Thus,the two species can be used as pioneer materials in afforestation.The G.biloba had water use strategies with a higher water consumption,lower water use efficiency and shallow water source.It is suitable for medium term restoration.