Data from: Leaf P increase outpaces leaf N in an Inner Mongolia grassland over 27 years

The dynamics of leaf nitrogen (N) and phosphorus (P) have been intensively explored in short-term experiments, but rarely at longer time scales. Here, we investigated leaf N:P stoichiometry over a 27-year interval in an Inner Mongolia grassland by comparing leaf N:P concentration of 2006 with of 1979. Across 80 species, both leaf N and P increased, but the increase in leaf N lagged behind that of leaf P, leading to a significant decrease in the N:P ratio. These changes in leaf N:P stoichiometry varied among functional groups. For leaf N, grasses increased, woody species tended to increase, while forbs showed no change. Unlike leaf N, leaf P of grasses and forbs increased, while woody species showed no change. Such changes may reflect N deposition and P release induced by soil acidification over the past decades. The interannual effect of precipitation may somewhat have reduced the soil available N, leading to the more modest increase of leaf N than of leaf P. Thus, leaf N:P stoichiometry significantly responded to long-term environmental changes in this temperate steppe, but different functional groups responded differently. Our results indicate that conclusions of plant stoichiometry under short-term N fertilization should be treated with caution when extrapolating to longer time scales.