The sensitivity of a species-rich flood-meadow plant community to fertilizer nitrogen: the Luznice river floodplain, Czech Republic

Concerns over the relative stability or sensitivity of biologically diverse ecosystems in relation to environmental change include the effects of land-use intensification on diverse plant communities. This paper examines the sensitivity of a floristically diverse flood-meadow under hay-cutting management to nitrogen enrichment, this being a key component of intensified agricultural management. A gradient of fertilizer nitrogen treatments was applied to a site in the Czech Republic in two successive seasons and plant community response was monitored using measures of species diversity, cover and above-ground primary production. Results show that diversity was supported by annual hay-cutting management and that the community was highly sensitive to nitrogen enrichment. Fertilization at rates consistent with intensive agricultural practice reduced species richness significantly within eight weeks, with forbs and moss particularly susceptible. The cover and biomass of some grasses were stimulated by fertilization until constrained by litter accumulation. Over two seasons, fertilization significantly reduced species diversity and simplified community structure as inter-specific competitive relations shifted. Biologically diverse flood-meadows therefore seem to be vulnerable to agricultural intensification and other human activities that promote enhanced nitrogen levels.