Soil quality index as a tool for Scots pine (Pinus sylvestris) monoculture conversion planning on afforested, reclaimed mine land

Abstract

In Central Europe, a large portion of post-mining sites were afforested with Scots pine, which is characterized by good adaptability and a tolerance for poor habitat at the beginning of forest ecosystem development. Conversion of monoculture on mine sites into more biodiverse mixed hardwood forests, especially on more fertile deposits, can be an emerging need in this part of Europe in next decades. The ability to classify the forests at these post-mining sites will facilitate proper species selection as well as the management and formation of the developed ecosystem’s stability. This work describes the guidelines that can be followed to assess reclaimed mine soil (RMS) quality, using the mine soil quality index (MSQI) and a classification of developed forest sites as a basis of tree-stand species selection and conversion of pine monocultures. The research was conducted on four post-mining facilities (lignite, hard coal, sulphur, and sand pit mining areas) on different RMS substrates dominant in Central Europe. Soil quality assessment takes into account the following features of the soil: texture soil nutrients (Ca, Mg, K, Na, P); acidity (pH KCl); and Corg-to-Nt ratio in the initial organic horizon. An analysis was conducted of classification systems using the MSQI validation correlation (at p =0.05) with vegetation features affected by succession: aboveground biomass of forest floor and ecological indicators of vascular plants (calculated on the basis of Ellenberg’s (2009) system). Eventually, in the analysed data set, the MSQI ranged from 0.270 for soils on quaternary sands to 0.720 for a mix of quaternary loamy sands with neogene clays. Potential forest habitat types and the role of the pine in the next generation of tree stands on different RMS parent rock substrate were proposed.