Relationship between tree transpiration and soil properties: Do trees with higher water demand promote formation of soils with higher water retention?

Soil water availability influence plant growth, vegetation, particularly trees, can in turn substantially alter soil properties affecting soil water availability. This study investigates whether tree species with higher transpiration rates promote the development of soils with a higher water-holding capacity using common garden experiment in post-mining heap in northwest Czechia, where several tree species were planted directly into bare overburden. We focused on three monocultures of alder (Alnus glutinosa), oak (Quercus robur), and spruce (Picea omorica). Tree sap flow was measured and used to estimate transpiration at both individual and stand levels. At the same time, soil moisture and water-holding capacity were assessed in each stand. Alder and oak showed similarly high transpiration rates, significantly exceeding those of spruce. The alder stand exhibited the highest average annual soil moisture as well as the highest moisture during the vegetation and dormant season, significantly differing from oak and spruce, while oak soils had a significantly higher moisture than spruce. Water-holding capacity was the highest in oak soils, significantly exceeding that of alder and spruce. These results support the hypothesis that tree species with a higher water demand foster the development of soils with an enhanced water retention capacity.