Some rare plant species in the Aktolagay cretaceous massif (Republic of Kazakhstan): the characteristics of populations

Abstract
Cretaceous massifs of the Eurasian continent are unique not only for their geological features but also for the peculiar flora. Therefore, the identification and study of the biodiversity of these unique objects is currently an actual task. Comprehensive studies of the flora and vegetation of the Aktolagay cretaceous massif (Republic of Kazakhstan) were carried out in 2019. One of the study aspects was the consideration of the ecological and biological features of several plant species typical for this territory. The research is devoted to the study of five plant species: Astragalus lasiophyllus Lеdеb., Astragalus vulpinus Willd., Matthiola tatarica (Pall.) DC., Eremurus inderiensis (M. Bieb.) Regel, Tragopogon ruber S.G. Gmel. The coenopopulations (CP) of the species are located in the lower parts of the slopes, as well as in aligned areas at the foot on cretaceous substrates, and on sandstone soils. The total density of the studied CPs varies from 2.2 to 6.6 ind./m2, the effective density varies from 1.6 to 4.9 ind./m2. The studied coenopopulations belong to normal incomplete ones. The most typical feature is the absence of seedlings, juvenile and senile individuals in the spectrum, while the peak falls on mature generative individuals, in the Mattiolla tatarica coenopopulations – on virginile individuals. Coenopopulations differ in their type ("delta-omega" criterion): the Matthiola tatarica one is young, the CP of Astragalus lasiophyllus is transitional, the CPs of Astragalus vulpinus and Eremurus inderiensis are maturing, and the CP of Tragogon ruber is mature. The recruitment index is high in the CP of Matthiola tatarica (3.05), in the rest of the CPs it is not higher than one (0.36-0.82), the ageing index is equal or close to zero (0.00–0.10). Most morphometric features show the low levels of variability and plasticity.