Population structure and reproductive success of Cypripedium calceolus (Orchidaceae, Liliopsida) on karst landscapes of Southern Timan (Komi Republic): Slope exposure influence

The influence of slope exposure on the population structure, morphometric features and reproductive characteristics of the rare orchid Cypripedium calceolus L. on karst landscapes of the Southern Timan in the territory of the Paraskiny Lakes Nature Reserve (northeast of the European Russia) was studied. In 2023, six populations of the species were surveyed on karst landforms, namely: five ones on slopes with different exposures, and one on a flat area. It has been revealed that the species forms its largest populations on the slopes of the western and northwestern exposures. Generative shoots damaged by light frosts were noted in all populations, and their share was more than 50% on the western slopes. The slope exposure affects the morphometric parameters of shoots and seeds. Fruit set is associated with both weather conditions and exposure, namely: the lowest fruit set was noted on the cold northwestern slopes, while the highest was on the southern ones. A decrease in the actual seed productivity of the fruit was revealed as the orientation of the slopes changed from north to south (from 9861 down to 3761 pcs), which is associated with the underdevelopment of some seeds. The average actual seed productivity of the generative shoot at the karst outlets of the Southern Timan was 1292 pcs (from 985 up to 1769 seeds in different populations). Along with the vegetative renewal characteristic of this species, seed renewal was also noted in the studied populations, as evidenced by the presence of juvenile individuals therein, whose proportion varied from 1 to 13.5%.