The dynamics of Listera ovata populations on mineral islands in the Biebrza National Park

Abstract

Observations of two isolated populations of Listera ovata (Oparzelisko and Zabudnik) were conducted for 7 years in the Biebrza National Park. The studied populations differed in size, proportion of flowering individuals and effectiveness of reproduction. High number of juvenile individuals in OPA population was noted under conditions more favourable for germination (gaps in vegetation and higher moisture of soil). On the other hand, vegetative reproduction is important in the dynamics of ZAB population. The natural fruiting rate of L. ovata is relatively high (up to 90%) and does not seem to be pollinator limited. Some costs of reproduction especially in terms of leaf size were observed. The dormancy is important in the population dynamics. In some years even one third of the population may be dormant. L. ovata produces enough seeds and offspring to maintain or even increase population sizes. These facts, connected with the longevity of individuals,indicate that populations of L. ovata in the Biebrza National Park are not threatened with extinction in the nearest future.