Dynamics of species richness of floodplain meadows

The effects of different nutrition level on dynamics of species richness and total stand composition were observed in a permanent grassland (association Stellario-Deschnmpsietum FREITAG 1957, initial stand type Alopecuretum) in floodplain of upper Luznice River, South Bohemia, between 1987 and 1999. A sinusoid oscillation with ten- or eleven-year cycle along totally zero trend of increase in species richness was observed in the non-fertilized stand. A depression in species richness occurred initially in the fertilized stands. Depression rate and duration of that period increased continually with increasing N doses. There were observed yearly decline 1.63 species and depression duration till about ninth year since the initial fertilization with 300 kg N + PK. The increase in species richness started to reach a threshold level of growth resilience (e(t) > +0.1) with about one year delay after the turning point (minimum species count). As results from the observations, changes in grassland species richness are affected by nutrient doses (preferably by N) and duration of their application. A procedure for marginal species richness calculation described in the article seems to be an appropriate dynamic characteristics for specification of species richness development.