不同生活型绿化植物叶片碳同位素组成的季节特征

Seasonal differences in leaf carbon isotope composition among landscaping species of different life forms in Beijing,China

通过测定北京地区不同生活型绿化植物叶片的碳同位素组成(δ13C值),从植物种和生活型两个方面研究植物水分利用效率的自然可变性。结果表明:所测定的75种植物(隶属于35科65属)的叶片的δ13C值变幅,春季为-30.7‰--23.4‰,夏季为-31.5‰--25.1‰,秋季为-31.4‰--23.9‰;落叶灌木种间差异不显著(p=0.114),而常绿乔木(p=0.005)、落叶乔木(p<0.001)、常绿灌木(p=0.022)、草本植物(p<0.001)和藤本植物(p=0.001)的种间差异显著或极显著;同一生活型植物叶片的δ13C季节差异显著,春季叶片的δ13C值显著大于夏秋两季(常绿乔木除外),不同生活型植物叶片的δ13C值在春、夏、秋3个季节差异都达到了极显著水平(春季p=0.001、夏季p<0.001、秋季p<0.001),且叶片的δ13C值表现出乔木树种>灌木树种>藤本植物>草本植物、常绿植物>落叶植物的规律。因此,植物种和生活型均会引起植物叶片δ13C值的变化,但δ13C受生活型变化的影响较大,表明不同生活型植物的水分利用效率具有明显差异。

Aims Plants with high water use efficiency could contribute to an overall lower water-using landscape. Our objective was to analyze differences in water use efficiency among landscaping plants in Beijing, China. Methods We used stable carbon isotope techniques to investigate δ^13C values of 75 species belonging to 35 families and 65 genera in spring, summer and autumn in 2006 and analyzed variations in water use efficiency of different plant species and different life forms （evergreen tree, deciduous tree, evergreen shrub, deciduous shrub, forb and liana）.Important findings Leaf δ^13C values varied between -30.7‰ and -23.4‰ in spring, -31.5‰ and -25.1‰ in summer and -31.4‰ and -23.9‰ in autumn. Differences of δ^13C values were not significant in deciduous shrub species （p = 0.114）, but were significant in evergreen trees （p = 0.005）, deciduous trees （p 〈 0.001）, evergreen shrubs （p = 0.022）, forbs （p 〈 0.001） and lianas （p = 0.001）. Leaf δ^13C values were significantly different among seasons, being greater in spring than in summer and autumn （except for evergreen trees）. The δ^13C values for life forms were significantly different in different seasons, with a sequence of trees〉shrubs〉lianas〉forbs, and evergreen plants〉deciduous plants. Results showed that variation of leaf δ^13C is dependent on species and life form, especially life form, and that water use efficiency differed greatly among life forms.