Stoichiometric characteristics of carbon, nitrogen and phosphorus in the leaves of 42 woody landscape plants in Lanzhou City of northwestern China

  Objective  The contents and ratios of carbon (C), nitrogen (N) and phosphorus (P) in plant leaves are the results of long-term adaptation of plants to the environment. Study of leaf stoichiometry characteristics of woody landscape plants in arid areas of northwestern China can provide a data basis for the accurate planning and construction of large-scale models of planting in similar cities.

  Method  In this study, the C, N and P stoichiometric characteristics of 42 common woody landscape plants in the main urban district of Lanzhou City of northwestern China (Qilihe District, Anning District and Xigu District) were analyzed. The 42 plant species were classified into trees (26 species) and shrubs (16 species), evergreen (7 species) and deciduous (35 species), coniferous (5 species) and broadleaved (37 species). Variation characteristics of leaves’ contents of C, N, P, C∶N, C∶P and N∶P of different life types, and the relationship between the variation characteristics and specific leaf mass (LMA) were analyzed.

  Result  (1) The average contents of C, N and P of 42 woody landscape plants were 39.67%, 2.45% and 0.17%, respectively. The average C∶N, C∶P and N∶P were 17.17, 232.98 and 14.72, respectively. Compared with the global scale, the contents of C and P and C∶N in leaves of woody plants in Lanzhou City were relatively low, while the contents of N∶P in leaves were relatively high. (2) Stoichiometric characteristics varied among different plant life types. The C content, C∶N, C∶P and N:P of the leaves of trees were higher than those of shrubs, and the content of N and P was lower than that of shrubs. The leaf N and P content of deciduous tree species was higher than that of evergreen tree species. The leaves of broadleaved tree species had higher leaf N and P content than coniferous tree species. (3) The analysis of the correlations between plant leaf traits showed that leaf C content was positively correlated with C∶N and C∶P (P < 0.01). There was a synergistic relationship between LMA and leaf C content, but an opposite relationship between LMA and leaf N and P content.

  Conclusion  It is preliminarily indicated that the development of woody landscape plants in Lanzhou City is limited by N elements during the growing season, and it is suggested that nitrogenous fertilizer can be increased appropriately during the ecological environmental improvement in this area.