Population-ontogenetic aspects of the life strategy of Traunsteinera sphaerica (M. Bieb.) Schltr. (Orchidaceae) under the conditions of anthropogenic pressure on meadow ecosystems of the Central Caucasus

Abstract

We studied variation of morphological characters, ontogenetic structure and vitality of 10 cenopopulations of Traunsteinera sphaerica (M. Bieb.) Schltr. within the Kabardino-Balkar Republic. The studies were conducted in the meadow plant communities under different conditions of anthropogenic load (recreation and grazing). The species presents medium phytocoenotic plasticity of morphological characters (I_p=0,51%) and high variation of morphological characters (CV_х¯ср=20,08-42,66%). The maximum increase of the cenopopulation vitality with the stable seed reproduction is observed in the composition of undisturbed meadows; the portion of generative individuals is increased in ontogenetic spectra (55,9-65,3%). Under the intensification of the anthropogenic load, vitality of cenopopulations and the density of individuals (0,64 ind./m²) are decreased; the portion of virginal individuals is increased in ontogenetic spectra. The rate of the seed reproduction of cenopopulations, in which the density of individuals accounts for 18,24-23,17 ind./m², is high on the rubbly substrata with low total projective cover (75-80%).