Long-term residual effect of short-term fertilizer application on Ca, N and P concentrations in grasses Nardus stricta L. and Avenella flexuosa L.

Abstract

The resilience (the ability of an ecosystem to recover after termination of perturbation) of plant species composition after short-term fertilizer application can take decades in sub-alpine grassland, but little attention has been paid to the resilience of nutrient concentrations in the biomass of individual plant species. In 2004, an abandoned experiment in which phosphorus, nitrogen and calcium had been applied from 1965 to 1967 was identified in the Giant Mts. (Krkonose/Karkonosze, Czech Republic). The biomass of two dominant grasses, Nardus stricta and Avenella flexuosa, was analyzed for Ca, N and P concentrations 37 years after the last fertilizer application. In treatments with P application, the P concentration was still significantly increased in both species. The N concentration was higher in treatments with N or Ca application and the lowest in P treatments. The N:P ratio ranged from 7.7 to 16.6 and from 6.2 to 16.3 in N. stricta and A. flexuosa, respectively, and was lowest in P treatments where A. flexuosa predominated. N. stricta dominated in treatments where the biomass N:P ratio was higher than 13, whereas lower ratios were more favourable for A. flexuosa. In the case of N. stricta, the Ca concentration was increased in Ca treatments. Ca and P concentrations in N. stricta biomass were significantly positively correlated with soil plant available P and Ca concentrations, but this was not recorded for A. flexuosa. In environments with different P availability, the competitive ability of investigated species was predetermined by the N:P ratio in their biomass. As in the case of plant species composition and soil chemical properties, the resilience of Ca, N and P concentrations in the biomass of individual species can take decades in sub-alpine grassland.