Impact of Secondary Succession in the Xerothermic Grassland on the Population of the Eastern Pasque Flower (Pulsatilla patens)—Preliminary Studies

Abstract

We studied the impact of secondary succession in xerothermic grasslands on a population of Pulsatilla patens, a species of European Community interest. We established two permanent plots with a high number of individuals of P. patens in a xerothermic grassland in Southern Poland. We compared two areas, the first in open grassland (plot A), and the second with overgrowing vegetation (plot B). We assessed the population structure as well as the individual traits of the species. The total abundance of P. patens in the open xerothermic grassland was five times higher than in the overgrowing xerothermic grassland. A randomly clustering distribution was noted only in plot A; in plot B a random type of distribution occurred. The density structure of the rosettes was higher in plot A. The mean number of leaves in rosettes of P. patens as well as dimensions of intermediate stems and leaves of the species is strongly correlated with habitat conditions. The shadowing caused by shrubs and trees and high weeds observed in the overgrowing xerothermic grassland negatively impacted on the number of individuals, distribution, structure and morphology of P. patens.