Tree species and soil substrate affect buffer capacity of anthroposols in afforested postmine sites in Poland

Abstract

The study presents the influence of tree species and soil substrate on the buffer capacity of anthroposols at two afforested postmine sites (Piaseczno and Szczakowa) in southern Poland. These postmine areas were reforested with homogenous stands of tree species Scots pine (Pinus sylvestris L.), common birch (Betula pendula Roth), European larch (Larix decidua Mill.), European oak (Quercus robur L.), and black alder (Alnus glutinosa Gaertn.), growing on various parent materials (substrates): mixed Quaternary sands and Neogene clays, Neogene clays, Quaternary sands, Quaternary loamy sands, and loams. Samples were taken from the 0 to 5 cm and 5 to 30 cm mineral soil layers. Basic soil properties such as soil texture, total organic carbon content (TOC), hydrolytic acidity, cation exchange capacity (CEC), and base saturation (BS) were investigated. The buffer capacity of the studied soils were measured by the Arrhenius method, and buffer surface areas (alkaline surface area [sNaOH], acid surface area [sHCl], and total buffer area [stotal]) were calculated using the definite integral. The highest buffer ability (stotal) was seen in stands of alder tree on Neogene clays in the 0 to 5 cm layer and the lowest were noted under pine trees on Quaternary sands in the 5 to 30 cm layer. The examined soils were usually characterized by a higher buffer capacity in the alkaline range than in the acid range. The study showed that the buffer capacity of the surface layers was most affected by the tree species, whereas in the deeper soil layers the capacity was most affected by the soil substrate. Buffer capacity was related to organic matter content (especially TOC and total nitrogen [N] content), soil texture, and sorption properties such as CEC and BS.