Population of Epipactis palustris (L.) Crantz (Orchidaceae) in south-western part of Poznań

During the last 10 years (2005–2014) the population of Epipactis palustris within the former ecological use “Kopanina 1” was observed five times. In subsequent years, on the area of 4400 m2 at least 1000 to more than 4000 ramets were noted. The ramets in generative phase of development always predominated. It might indicate good condition of the population. The highest density per unit of area was observed in the first year of the study. The length of stems and number of leaves were the most constant features in orchid population. Then the width of the bract was characterized by the greatest values of the coefficient of variation. During the entire study period the number of ramets in population of E. palustris fluctuated, mainly resulting from the biology of the species, and only substantially from the impact of weather conditions. Negative impact of diverse human activities and excessive expansion of the other plant species, which resulted in the shading of the orchid sites, are the major threats to E. palustris existence in the described object.