Effect of Forest Reclamation on Carbon Stocks and Respiration of Soils of Natural and Technogenic Ecosystems of Southern Karelia

Abstract

This paper presents the results of studies on soil carbon stock dynamics, CO₂ emission, and soil microbial respiration during post-industrial succession upon reforestation of a sand–gravel quarry in southern Karelia. In July 2021 and 2022, soils in the areas with different reforestation practices were studied. In 1991, one-year-old Scots pine (Pinus sylvestris L.) seedlings were planted on the plots with (1) sandy–gravelly mineral soil (sample plots SP 1 and SP 2) and (2) soil with added peat (SP 3). Native podburs (Entic Podzols) under undisturbed lingonberry pine forest (SP 4) were used as the control. We determined the total (organic) carbon, the microbial activity (using the basal and substrate-induced respiration methods in laboratory), and the CO₂ emission from the soil surface (in the field). The assessment of the properties of post-industrial soils indicated that the studied parameters in replantozem on SP 3 were close to those in the podzolized podbur on SP 4, which attested to a positive effect of peat-enriched substrate on the soil and plant recovery in the abandoned quarry. Considerably higher values of carbon stocks (by 6–10 times) and CO₂ fluxes (by 2–4 times) in the replantozem (Umbric Leptosols (Novic)) on SP 3 in comparison with psammozems (Skeletic Leptosols) on SP 1 and SP 2 were due to intensive organic matter accumulation and the application of peat substrate rich in nutrients and plant diaspores during planting. Soil carbon stocks, CO₂ emission, microbial activity, and stand productivity at SP 1 and SP 2 were lower than those at SP 3 and SP 4. To make more accurate predictions of the dynamics of the analyzed parameters of disturbed soils, it is necessary to take into account their spatial and temporal variability.