Effect of texture and tree species on microbial properties of mine soils

Reestablishment of soil microbial communities is a prerequisite for successful reclamation of post-mining barrens. The objective of this study was to assess the effect of texture of soil substrate and the planted tree species on microbial properties of mine soils reclaimed for forestry. Soil samples were taken from loamy sands and sands afforested with Scots pine and silver birch either in monocultures or in the mixed stands. The samples were measured for the contents of organic C (Corg), total N (Nt) and pH. The examined microbial properties included basal respiration (RESP), microbial biomass (Cmic), Cmic-to-Corg ratio, activities of dehydrogenase, acid phosphomonoesterase and urease and community level physiological profiles (CLPPs) studied using Biolog® Ecoplates. The loamy sands had higher pH, contained more Corg, Nt and Cmic and exhibited higher basal respiration and enzyme activities than the sands. However, their Cmic-to-Corg ratio was lower indicating less availability of Corg for soil microbes compared with the sands. The CLPPs in the loamy sands differed from those in the sands although there was no difference in microbial diversity (expressed as Shannon's diversity index) and activity on the Biolog® plates between the two textural classes. Tree species did not affect Corg, Nt and Corg-to-Nt ratio and had only a weak effect on CLPPs. However, the values of Cmic, RESP, Cmic-to-Corg ratio, dehydrogenase and urease activities were significantly lower under pine compared with the birch and mixed stands. The obtained results suggest that the texture of soil substrate is of higher importance for microbial properties of the studied mine soils than the planted vegetation.

Research highlights▶ Soil texture is more important for microbial properties than the vegetation. ▶ Contents of Corg and Nt are the major determinants of Cmic, RESP and enzyme activities. ▶ Physiological profiles of soil microbial communities depend mainly on soil pH. ▶ Mine soils under pine are less microbiologically active than those under birch.