Impact of Tree Species and Substrates on the Microbial and Physicochemical Properties of Reclaimed Mine Soil in the Novel Ecosystems

Abstract

Evaluating how different tree species and substrates affect the microbial and physicochemical properties of technosols from combustion wastes and reclaimed mine soil (RMS) is vital in species selection to enhance restored ecosystem services. This research aimed to evaluate the impact of pioneer and N-fixing tree species and substrates on the post-mining soil microbial and physicochemical properties. Common birch (Betula pendula Roth) and Scots pine (Pinus sylvestris L.), as the commonly introduced species on reclaimed mine soils (RMS) in eastern and central Europe, were selected as pioneer species, whereas black alder (Alnus glutinosa (L) Gaernt.) and black locust (Robinia pseudoacacia L.) were selected as N-fixer species. Soil samples were collected from different RMS developed from three substrates (fly ashes, clay, and sand) and measured for the content of total nitrogen (Nt), organic carbon (Corg), exchangeable calcium (Ca2+), exchangeable potassium (K+), exchangeable magnesium (Mg2+), C to N ratio (C:N), basal respiration rate (RESP), and microbial biomass carbon (Cmic). The research indicated that tested tree species influenced water holding capacity (WHC), Nt, C:N, and RESP value. The highest Nt accumulation in soil was observed under N-fixing, but it did not transfer into higher organic carbon content under N-fixers. The soil under pine had a greater C:N ratio than the soil under birch, alder, and locust. The RESP rate was highest under birch. In terms of substrate type, RMS developed on Miocene clays exhibited higher carbon and macronutrient contents followed by ashes, whereas sands exhibited the lowest values of both physicochemical and microbial properties. The study suggested that both tree species and substrates affect microbial activities and physicochemical properties of RMS; however, the substrate effect is stronger.