Relationship between leaf phosphorus concentration and soil phosphorus availability across Inner Mongolia grassland
内蒙古草地叶片磷含量与土壤有效磷的关系

Aims Phosphorus status and N/P stoichiometry in plant leaves have been studied intensively with recent focus on large-scale patterns and driving factors. Studies of Chinese terrestrial plants found that leaf P was considerably lower than the global average, resulting in a higher N/P, probably due to the low soil total P content at the national scale. Inner Mongolia grassland offers a diverse array of taxa and soil conditions to examine the correlation between leaf and soil P concentrations. Our objective was to determine how and to what extent soil total and available P modify leaf P across the study region. Methods Leaf samples of 57 species were collected at 36 sites across Inner Mongolia grassland during July and August 2007. We determined leaf P concentration, N/P, soil total and available P concentrations and tested pairwise relationships between leaf and soil variables at species-by-site, inter-specific and inter-site levels. Important findings Findings of relatively low leaf P and high N/P across Inner Mongolia grassland were consistent with previous findings. Neither soil total nor available P appeared to be related with leaf P concentration, although soil available P had a stronger explanatory power than soil total P content. Moreover, Inner Mongolian grassland did not show a great shortage of soil available P compared with USA, Australia and the global average. The hypothesis that low leaf P and high N/P of plants are caused by low soil P content do not hold in Inner Mongolian grassland. Instead, neither soil total nor available P shapes the pattern of leaf P and N/P across this grassland.