Effect of environmental factors on the structure of populations of Pulsatilla patens (L.) Mill.

摘要

Pulsatilla patens is a rare and endangered component of the European flora. In Poland, the principal area occupied by the species is in north-eastern part of the country. The study of the Pulsatilla patens populations was conducted in 2011-2012, in the 15 sites in the two Natura 2000 wildlife refuges: the Myszynickie Bory Sasankowe and the Military Training Grounds in Orzysz. The purposes of the study have been to analyze the structure of populations of Pulsatilla patens growing in two types of habitats: forest and non-forest ones; to analyze the influence of selected habitat-specific characteristics on the structure of Easter pasque flower populations; to work out a model which will explain the dependence of the structure of a population of Pulsatilla patens on environmental conditions. Most of the populations (10) grew at the forest sites. They were less numerous, with an average of 9 rosettes at mean in site, in total, comprised 89 rosettes of P. patens. On the non-forest populations, in total 206 rosettes of P. patens were counted, the average number of rosettes in a population was about 41; the average number of flowering rosettes reached ca 16. On forest sites, flowering rosettes had on average 3 flowers, whereas on non-forest sites the analogous number was 5.5. In forest sites statistical analysis has shown the positive correlation between the number of fruiting rosettes and the shading in the shrub layer as well as the negative correlation between the number of fruiting rosettes and the share of space potentially suitable for germination. In non-forest habitats, the relationship between the number of fruiting rosettes and the shading in the herbaceous vegetation layer is worth noticing. The comparative analysis accomplished with U Mann-Whitney test on both population and habitat characteristics relative to the habitat as a variable (forest or non-forest) showed statically significant differences between the number of rosettes and shading in layer of trees. Ordinance RDA explains about 62.7% of the total population variability.