The influence of introduced tree species on the relationships between soil buffering capacity and ecological groups of microorganisms in urban park soils

As a component of urban parks, soil is an essential part of urban green infrastructure; soil influences the green plantings in megacities, being affected by environmentally unfavorable factors. To reveal relationships between soil buffering capacity and ecological microbial groups of park soils, soil acid-base buffering capacity (pHBC) was determined with the Arrhenius method. We counted the soil microorganisms using differential diagnostic nutrient media with serial dilutions. Soil microbial biomass was determined by thermal rehydration. In statistical data processing, we used the methods of descriptive statistics, univariate analysis of variance, etc. We established strong positive correlations between pH values and pHBC in the acid and acid-base range, and a negative correlation between pH values and buffering capacity in the alkaline range; a strong correlation between the abundancies of amylolytic and pedotrophic soil microorganisms. We determined the effect of the three following soil sustainability-associated latent factors: Factor 1 – effect correlated with total pHBC, pHBC in the acid range and soil acidity, Factor 2 and Factor 3 – effects characterized by the direction of microbial processes and which formed a balanced system between the soil humus decomposition and the entry of plant litter. We revealed a beneficial impact of subcrown space on the abundancies of soil microorganisms. We recommend using acid and acid-base buffering capacity and microbiological characteristics as soil quality indicators. The abundance of soil microorganisms increased in the forested sites.