Physical and chemical characteristics of soils in the places of the cenopopulation of the tulipa species in the natural reserve "The Black Soil"

The article contains materials on the study of the edaphic conditions of the growth of the cenopopulations of Tulipa gesneriana, T. biflora and T. biebersteiniana in the conditions of the state natural biosphere reserve (GPBZ) “Chorniye Zemli (Black Lands)”. The species belong to the number of rare and protected plants in many regions of Russia, including the Republic of Kalmykia. The soil samples were examined, with a detailed morphological description of the soil horizons; also, an analysis was made of the humus content, the composition of the cations and anions, and the granulometric composition of the samples by conventional methods. The cenopopulation of Tulipa gesneriana No. 1 is limited to the herbaceous-grass (Poaceae-Mixteherbosa) community. The physical-chemical analysis conducted has shown that the soil where the cenopopulation grows is meadow-chestnut solonetzic. There is a high humus content (6.15%) in the A1 horizon of the soil, which decreases with depth by, at least, 3.09%. The analysis of the chemical composition of the aqueous extract has indicated that the soil is not saline to a depth of 80 cm. The populations of Tulipa gesneriana No. 2 and T. biebersteiniana No. 8 are characteristic of the mixed-fescue-fescue-wormwood (Artemisia austriaca-Festuca valesiaca- Mixteherbosa) community. According to the physical-chemical characteristics of the soil, the habitats of this cenopopulation are also meadow-chestnut solonetzic (presumably saline beginning at the depth of 100 cm). The humus content of the soil in the horizon A1 is 2.77%, while further along the horizons it decreases by 1.03-2.03%. According to the analysis of water extracts, the soil is not saline up to a depth of 100 cm. The cenopopulations of Tulipa biflora No. 3 and No. 4 belong to the onion-oligophrenic-lethospheric (Artemisia lerchéana-Poa bulbosa) and ephemeral-onion-branched Artemisia (Ephemerosa) plant communities respectively. The data of the physical-chemical analysis of the soil at the site where they grow has shown that both plant communities are formed on solonchak-solonetzic soils. The soil humus in horizons A, B and BC in these communities is 2.15% - 2.29%, 1.50% - 1.62%, and 1.37% - 1.45%, respectively; they are saline with 10 cm sodium chloride: weakly in the layer of 10-20 cm, and to an average degree in the layer of 20-50 cm. Cenopopulations No. 5 and No. 6 of Tulipa biebersteiniana grow in the mixed ephemeral-onion-brittle-wormwood (Artemisia-Poa bulbosa-Ephemerosa) and ephemeral-onion-oligotrophic (Poa bulbosa-Ephemerosa) plant communities, respectively. The physical-chemical analysis carried out has revealed that these communities are formed on brown semi-desert light loamy soils. Such soils have a low humus content, reaching 1.29% - 1.37% in their upper layer; they were not saline up to a depth of 50 cm. The cenopopulation of Tulipa biebersteiniana No. 7 is found in the herbage-grass-lepherin (Artemisia lerchеana-Poaceae-Mixteherbosa). The site where this soil population is localized is characterized with meadow-chestnut solonetzic soils with a high soil humus content in the A1 horizon (6.38%), which decreases by 3.15% or more with depth. The analysis of the chemical composition of the water extracts has indicated that the soil is not saline up to a depth of 80 cm.