Contribution of root respiration to total soil respiration during non-growing season in mine reclaimed soil with different covering soil thicknesses

An accurate assessment of root respiration in mine reclaimed soil is important for effectively evaluating mining area ecosystems. This study investigated dynamic changes in root respiration and the contribution of root respiration to total soil respiration (Rr/Rt ratio) during the non-growing season in mine reclaimed soil, with different covering-soil thicknesses. According to the covering-soil thicknesses, the study area was divided into four sites: 10–25 cm (site A), 25–45 cm (site B), 45–55 cm (site C), and 55–65 cm (site D). From November 2017 to April 2018 (except February in 2018), the soil respiration, root respiration, temperature at 5 cm, water content, and root biomass were measured. The results show that soil temperature and root respiration exhibited similar diurnal and monthly variations. The root respiration is strongly influenced by soil temperature during the non-growing season, with an exponential and positive relationship (P < 0.001). Root respiration varies with the covering-soil thickness and is greatest with a covering-soil thickness of 25–45 cm. The Rr/Rt ratio also exhibits monthly variations. During the non-growing season, the mean value of the Rr/Rt ratio is 51.15% in mine reclaimed soil. The study indicates that root respiration is the primary source of soil respiration and is an important factor for estimating the potential emission of soil CO2 from mine reclaimed soil at the regional scale.