Impact of weather conditions on the seasonal development, population structure and reproductive success of Dactylorhiza incarnata s. l. (Orchidaceae, Liliopsida) in the Komi Republic

Abstract

The results of our eight-year study of a population of the rare orchid Dactylorhiza incarnata subsp. cruenta at the northern limit of its range (the Komi Republic) are presented. Weather factors (air temperature and precipitations) were revealed to influence features of the small and big life cycles of this species. The number of plants in the studied population was influenced by the weather conditions of the previous growing season, positively by the temperature in August and negatively by frosts in October. The number of generative (flowering) plants had a positive correlation with the air temperature in July of the previous vegetative season. The fruit set was high (71.2%) and negatively associated with precipitation during flowering of this species. The seed number per fruit in the studied population (9,831 pcs on average) was higher than that in the more southern parts of the range of this species. This indicator, as well as the real seed productivity of the species, is positively related to the level of moisture availability of the current growing season. The seed production is high, from 34 thousand to 154.6 thousand seeds per 1 m2 in several study years, it is positively associated with the sum of active temperatures of the previous growing season. The presence of juvenile individuals (10.0–31.7%) over all study years indicates a successful seed reproduction in this population.