Effect of Lighting Conditions on the Reproductive Success of Cypripedium calceolus L. (Orchidaceae, Liliopsida)

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Abstract—The influence of lighting conditions on the reproductive characteristics of Cypripedium calceolus L. was studied on the territory of the Komi Republic, where the species is located on the northern border of its habitat. The study was carried out in the southern part of the region (within the Vychegda-Mezen’ Plain) in 2017. Eight cenopopulations of the species in areas with various light intensities were examined, among which three cenopopulations were in swamps and five were in forests with varying degrees of closeness of the canopy. We used the index of “canopy closure” as a measure of light conditions in the areas of growth of C. calceolus. To evaluate this index, the method of analysis of digital hemispherical photographs obtained using a 180° ultra-wide-angle Fish-eye lens was used. Photographs were processed and analyzed using the Gimp 2.8 graphical package (GNU Image Manipulation Program, GIMP Team). Open habitats (with an index of canopy closure of less than 65%) were shown to be more favorable for the seed reproduction of C. calceolus. The pollination efficiency, real seed productivity, and the number of juvenile plants of seed origin are higher in such places. In addition, the later vegetation start in swamps allows the plants to avoid damage by late spring frosts. In more shaded habitats, the vegetative renewal of C. calceolus comes to the fore; all studied cenopopulations of the species in such conditions were more stable and aimed at survival.