Population dynamics and seed productivity of Dactylorhiza maculata (Orchidaceae) population in the Komi Republic (European Russia) as a response to the effects of weather factors

Abstract

Conservation of biodiversity is the most important problem at present time. One of its important tasks is a preserving of selected species and groups of plants. The Orchidaceae family, despite its high species diversity, is one of the most threatened groups of flowering plants in the world, which is caused by peculiarities of their biology and ornamental properties. One of the priorities in the study and conservation of Orchidaceae is long-term monitoring studies. This paper presents results of a nine-year study of the population of a rare orchid, Dactylorhiza maculata, in the Komi Republic (north-east of European Russia). The morphological features of plants and seeds, the number and structure of population and the reproductive success have been studied. It was revealed that the height of the Dactylorhiza maculata shoots is influenced by the weather conditions of the current growing season, while the number of leaves and flowers is influenced by the conditions of the previous year. The number of reproductive shoots in the Dactylorhiza maculata population is positively correlated with the temperature in July of the previous growing season. The fruit set varied between 26.0% and 73.7% during various study years. A significant positive correlation was found between the seed size and the precipitation amount at the mid-July of the current growing season. The average seed number was 3865 per fruit (by changing between 2557 and 4808 seeds in various study years). The real seed productivity was 32 761 seeds (with changes from 17 830 seeds to 41 548 seeds). A positive correlation was observed between the size of flowers and the number of seeds per fruit; these parameters positively correlate with the precipitation amount at the beginning of the growing season. The presence of juvenile individuals (from 10.8% to 24.2%) in all study years indicates the successful seed reproduction in the studied Dactylorhiza maculata population.