The population structure of Nepeta pamirensis at different altitudes in the Pamirs (Tajikistan)

Abstract

The structure of alpine plant populations is one of the main criteria for assessing the current state of alpine flora. Species of the genus Nepeta, most of which belong to alpine plants, can be universal objects for assessing changes in environmental conditions, including the impact of anthropogenic pressure. The article discusses the ontogenetic structure and population size in connection with the change in the life form of Nepeta pamirensis at different heights of the Pamirs (3060-4250 m a.s.l.). Our research showed that the ontogenetic spectra of different populations are different. These differences are linked to changes in the life form, the length of ontogenesis and how well seeds reproduce. Populations were studied using transects. The individual seed was taken as the counting unit. In total, 3 populations were studied and more than 750 individuals of different ontogenetic states were included in the analysis. The ontogenetic structure of populations was characterized using basic demographic indicators: the recovery index, ageing index, generative index and the ecological density index. Depending on the altitude gradient, the species was characterized by different efficiencies of seed reproduction, which determined the different densities of individuals in plant communities of distribution. In general, with an increase in the height of distribution of a species, the structure of the population became more stable.