Rates of anthropogenic transformation of soils in the Botanical Garden of Jagiellonian University in Kraków (Poland)

Soils in botanical gardens play a crucial role as they condition the growth and vegetation of huge diversity of plant species on relatively small areas. Creating favourable habitats for the planted vegetation's development frequently leads to the formation of soils with thick surface horizons with a very well developed structure, rich in organic matter and nutrients, described as hortisols. Despite significant human influence, the environments of botanical gardens are often considered to be seminatural enclaves in urban areas. The main objectives of the presented paper were to explain soil cover differentiation noted across the Botanical Garden of Jagiellonian University in Kraków and determine the share of natural and anthropogenic features in the studied soils. Moreover, the usefulness of the WRB system in the evaluation of the rate of anthropogenic transformation in soils was tested. All the investigated soils showed significant evidences of anthropogenic transformations. Both digging and overbuilding with allochthonous material rich in artefacts caused disturbances in soil morphology. On the other hand, formerly intensive liming and fertilizing with organic materials has resulted in the homogenization of soil chemical properties in the studied botanical garden. No significant relationships between the spatial differentiation of soil properties and diversity of planted vegetation or time span from the area's inclusion to the botanical garden were detected. The results of the bonitation of specific soil properties not considered by the classification system (e.g. thickness of soil profile overheap) were compatible with the WRB 2015 systematic position. This confirmed good definition of actual WRB criteria for soils disturbed by human activity and undergoing natural development.