Abstract
Abstract The investigation of soil conditions in plant habitats is an important area of research that enables the assessment of environmental factors determining species distribution in arid ecosystems. The aim of the present study was to comprehensively evaluate the physicochemical properties of soils in the natural habitats of Bryonia melanocarpa Nabiev in the southern part of the Kyzylkum Desert, Kazakhstan. The study was conducted using three soil profiles comprising a total of 16 samples collected from different soil horizons. Soil analyses included particle-size distribution, soil reaction (pH), electrical conductivity (EC), calcium carbonate (CaCO3) content, available phosphorus, exchangeable cations (Ca2+, Mg2+, K+, and Na+), and cation exchange capacity (CEC). The data were interpreted using heat maps, box plots, soil profile diagrams, and radar chart analysis. The investigated soils were characterized by slightly alkaline to alkaline conditions (pH 8.2-8.8), a predominance of exchangeable calcium, and relatively low cation exchange capacity (3.69-7.35 cmol(+)/kg). The highest CEC values, together with elevated concentrations of exchangeable magnesium and potassium, were recorded in the surface horizon of Profile 1. All soil profiles exhibited a decrease in available phosphorus with increasing depth, accompanied by a progressive increase in soil alkalinity. Profile 1 showed the highest carbonate content, whereas Profile 3 was distinguished by a heavier particle-size distribution and a relatively greater proportion of fine soil fractions. The obtained results demonstrate pronounced spatial heterogeneity in the soil conditions of Bryonia melanocarpa habitats and indicate that the combined effects of soil carbonate content, particle-size distribution, and cation exchange properties represent the principal edaphic factors shaping the ecological characteristics of this species in the southern Kyzylkum Desert.