The effect of environmental stressors on respiration activity of afforested mine soils

Abstract

Abstract:The functioning of soils strongly depends on the activity of the soil microbial communities and their ability to withstand diff erent environmental stresses. The aim of this work is to compare the eff ect of two frequently occurring stressors (drought-rewet and freeze-thaw cycles) on the basal respiration rate of mine and natural soils. Soil samples (n = 18) were delivered from the Szczakowa open-cast sand quarry in Poland. The samples were measured for organic matt er (OM) content, basal respiration, pH levels, and electric conductivity. The studied mine and natural soils had a similar texture and were classifi ed as loamy sands. The natural soils contained signifi cantly more OM than the mine soils but did not diff er in terms of pH. There were no signifi cant diff erences in the OM content, pH, and texture of the soils under the studied tree species (Pine, Birch, Larch). Mine soils exhibited signifi cantly lower initial respiration rate (RESP value) than the natural soils (1.34 μg C-CO 2 g −1 24 h −1 vs . 3.13 μg C-CO 2 g −1 24 h −1 ). Five freeze-thaw cycles reduced cumulative CO 2 evolution both in both the mine and the natural soils by 17.8% and 6.7%, respectively. Moreover, the reaction of the respiration rate to dry-rewet cycles diff ered distinctly between the mine and natural soils. In the natural soils, all dry-rewet cycles increased the respiration rate, wherein the increase was much more pronounced in the last two cycles. We conclude that periods of drought in the summer and freeze-thaw events in the autumn and spring may have a stronger negative eff ect on the functioning of forest ecosystems in the reclaimed lands than in natural stands.