Özet:

  This study addresses the question of how changing the mowing regime influences the floristic composition and floristic diversity of grasses in an experimental lowland meadow. The study location is Bia?owie?a Forest, NE Poland. To achieve the aim we used phytosociological data from long-term studies in Bia?owie?a Forest on the course of secondary succession. The relationship between the biodiversity of grasses and type of mowing was determined using statistical analysis. Changes in the dominance and frequency of individual grass species have occurred during the last 28 years of observations. The analysis of floristic similarity demonstrated a turnover of species between the individual years of observation. Principal component analysis showed that the change in mowing method resulted in a change of the species composition, cover, and domination. However, differences in the intensity of disturbance level were rather small (one cut yearly by scythe, by sickle bar mower, and by trimmer), and changes in floristic composition were also moderate in most years. During the initial years (1984?1990), Dactylis glomerata, Agrostis gigantea, and Anthoxanthum odoratum dominated. After 1990, Arrhenatherum elatius and Holcus lanatus spread and took over, with Trisetum flavescens joining them later. Between 2008 and 2012 the cover of Dactylis glomerata increased more than two times. The reasons for the floristic transformations were changes in the management mode, e.g., the transition from mowing by scythe (medium disturbance) to mechanized mowing, first by sickle bar mower (strong disturbance) and then by trimmer (weak disturbance).

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