Anthropogenic Soils of Botanical Gardens: A Review

Abstract

A review of publications on soils of botanical gardens forming in different landscape conditions and approaches to their classification is presented. Transformation of the soil profiles—the appearance of new horizons and features, acceleration or deceleration of pedogenetic processes, and, under conditions of intensive soil formation, relatively rapid disappearance of anthropogenic features—are noted for the soils of botanical gardens. Differentiation of the soil properties (pH, humus content, composition of the soil adsorption complex, nutrient content, etc.) within a given garden is due to differences in the duration of the anthropogenic impact on soils, land use history, introduced plants, soil and soil management. However, some general patterns of changes in the chemical properties of soils of botanical gardens relative to their natural background analogues can be identified. Soils of botanical garden are characterized by an increase in the humus content; the relative intensity of humus accumulation gains maximum in the botanical gardens of northern territories (the Bol’shoi Solovetskii Island, St. Petersburg); minimum differences with natural soils are observed in soils of the Mediterranean region and humid subtropics. The share of humic acids in the composition of humus also increases. The soil pH shifts towards higher values, especially in forest soils of the temperate and subtropical zones. The content of available nutrients (phosphorus and, sometimes, potassium) becomes higher. The diversity of the factors of anthropogenic influence on the soils of botanical gardens predetermines the diversity of their profiles. These soils combine the features of agrogenic soils (owing to their loosening and application of fertilizers), urban soils (owing to the application of various materials containing anthropogenic inclusions), and natural soils. According to the classification system of Russian soils, soils of botanical gardens can be classified the within the groups of agro-natural soils (agrosoils), agrozems, and agrostratozems; often, they belong to urbi-stratified subtypes of these and other soils.