Patterns of leaf nitrogen and phosphorus stoichiometry among Quercus acutissima provenances across China

Abstract

Provenance tests of forest trees provide an opportunity for assessing the intraspecific variation in leaf stoichiometry because climatic and edaphic differences associated with its geographic location are excluded. We determined the leaf N and P concentrations and N:P ratios for 31 Quercus acutissima provenances, and found there were significant differences in leaf N and P concentrations as well as in N:P ratios among these provenances. When grown under the same environmental conditions, the 31 provenances still retained significant patterns associated with their geographic origins. Leaf N and P concentrations declined toward the equator as mean annual temperature (MAT) increased, which can be explained by temperature-plant physiological stoichiometry. Leaf N concentration and leaf N:P ratios increased with increasing longitude due to the distribution of soil N content. Leaf P concentration initially decreased with increasing mean annual precipitation (MAP) up to 1500mmy−1, but then increased with further increase of MAP. Although there were significant differences in leaf N:P ratios among the 31 provenances, the relatively small coefficient variation (CV) in leaf N:P ratios and weak relationships between leaf N:P ratios and geographic origins, suggested a lower variation in leaf stoichiometry within the species when environmental influence was exclude in a common garden.