Morphological, Population and Phytochemical Assessment of Thermopsis mongolica (Fabaceae) in Steppe Communities of the Altai Republic

Eight coenopopulations of Thermopsis mongolica were studied in grazed steppe phytoceneses of the Altai Republic. Thermopsis is a medicinal, poisonous herbaceous long-rhizome perennial plant. The coenopopulations (CP) were assessed using a set of population and organismal characteristics, as well as the content of phenolic compounds in plant leaves and the antioxidant activity of T. mongolica extracts. The following organismal characteristics were selected: phytomass of the aboveground part, height of ramets, number of leaflets per shoot, length of a compound odd-pinnate leaf. The following population parameters were considered: total projective cover, projective cover of the species, proportion of generative partial formations, and ecological density. The position of each studied coenopopulation was assessed in points, corresponding to the value of each characteristic. Plants have the largest size, weight of the above-ground mass and length of the leaflets in the habitats near cattle pens, where Thermopsis colonized empty plots rich in humus. Population indices with maximum density values are also highest there. High indices are found in T. mongolica CPs in grazed communities with suppression of grass stand up to stage III of pasture degradation. The minimum points for organismal and population indices are found in plants under excessive grazing, with pasture devastation. According to the total score, CP 2 (thickets) has an optimal position, CP 8 (devastated pasture) — a pessimal one. In coenopopulations with intensive grazing and/or territories captured by Thermopsis, the higher content of phenolic compounds (more than 20 mg/g of absolutely dry weight in terms of gallic acid) in the leaves and beans was determined. Hydroalcoholic extracts of the same samples exhibited effective antioxidant activity (IC = 0.31–0.59 mg/ml).