The structure of Melilotus officinalis (L.) Pall. and Trifolium pratense L. populations on the territory of deciduous forests zone in Tatarstan Republic

The paper deals with the results of the Trifolium prаtense L. and Melilotus officinalis (L.) Pall. population structure study. This paper presents a comparative description of these species populations from different ecological and coenotical condition in the zone of deciduous forests in the Republic of Tatarstan. The evaluation of the morphological status of individuals in populations was carried out using such parameters as shoot height, number of shoots per plant, total number of inflorescences on a plant, dry shoots biomass, reproductive effort, photosynthetic effort, etc. Density, ontogenetic and vitality structure of populations are considered to be adaptive mechanisms of populations existence in different ecological-coenotic conditions. Studies have shown that in the composition of Melilotus officinalis populations most of the plants belong to the group of young or mature generative plants, in which the photosynthetic effort averages from 0,16 to 0,19, and the reproductive effort – from 0,12 to 0,19 in different communities. The greatest reproductive effort is observed in populations formed by plants with a low morphological status. Trifolium pratense forms populations of different vitality (prosperous, balanced, or depressed). The authors note the presence of plants of both generative and pregenerative periods in some communities, which indicates a successful seed renewal. The average values of the photosynthetic effort for Trifolium pratense in various growing conditions range from 0,20 to 0,36, and the reproductive effort – from 0,18 to 0,29. A higher reproductive effort was noted in populations at the boundary of the contact zones of deciduous forests and forest steppes.