Abstract:

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 δ¹³C 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 δ¹³C 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 δ¹³C 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 δ¹³C values were significantly different among seasons, being greater in spring than in summer and autumn (except for evergreen trees). The δ¹³C 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 δ¹³C is dependent on species and life form, especially life form, and that water use efficiency differed greatly among life forms.

Key words: carbon isotope composition, landscape plants, life form, seasonal characteristic, water use efficiency