Nutrient resorption of wetland graminoids is related to the type of nutrient limitation

1. Nitrogen or phosphorus limits plant growth in many wetlands. If specific mechanisms reducing losses of the growth-limiting nutrient have been favoured by selection, the N and P resorption efficiency (RE) during leaf senescence (NRE, PRE: the fraction of N or P resorbed) might depend on the type of nutrient limitation. 2. The size, mass, and N and P concentrations of green and senesced leaves were determined for 10 graminoid species at Dutch and Swiss wetland sites, with N : P ratios in leaves (6-27 by mass) indicating N or P limitation. 3. During senescence, leaf area decreased by 8-19%, and leaf mass by 8-38%; NRE ranged from 0 to 87%, and PRE from 30 to 96%. PRE correlated strongly with NRE (r = 0.91) but was, on average, 17% higher. Within the Swiss or Dutch sites, NRE and PRE did not correlate with foliar N : P ratios, indicating that RE was not directly adjusted to the type of nutrient limitation. 4. NRE and PRE were, on average, higher at the P-limited Swiss sites than at the N-limited Dutch sites. Because PRE exceeded NRE, high RE would be most beneficial when P limits plant growth. This may have contributed to the dominance of graminoids with high RE in P-limited wetlands.