Leaf nitrogen and phosphorus stoichiometry in 80 herbaceous plant species of Songnen grassland in Northeast China

Abstract

Aims Leaf nitrogen (N) and phosphorus (P) and N : P stoichiometry have been studied intensively in different regions in China. Songnen grassland is a natural region. Its dominant vegetation is meadow, which is determined by soil properties, and its flora is complex. Our objective was to find the stoichiometric patterns for this region. Methods Leaf samples of 80 herbaceous species were collected in Songnen grassland in August 2008. We de- termined leaf N, P, and N : P on both a mass and an area basis and tested the differences according to plant life forms and functional groups. Important findings Leaf N and P concentrations were (24.2 ± 0.96) and (2.0 ± 0.10) mg·g -1 on a mass basis and (13.0 ± 0.54) and (1.0 ± 0.05) mg·cm -2 on an area basis, respectively. N : P was (13.0 ± 0.39). Plant growth was limited by N in Songnen grassland. The concentration of leaf N and P and coefficient of variation were higher in annual plants than in other life forms on a mass basis, and there were no significant differences of leaf N concen- tration on an area basis and N : P between different life forms. Leaf N concentrations both on mass and area bases and N : P of legumes were higher than in other functional groups. There was no significant difference in the leaf P concentrations on an area basis among different life forms or functional groups. Our findings indicate that appro- priately increasing the proportion of legume plants would improve both the yield and quality of primary produc-