Shelterbelt farmland-afforestation induced SOC accrual with higher temperature stability: Cross-sites 1 m soil profiles analysis in NE China

Abstract

Shelterbelt farmland afforestation has been well-reported in its wind-break and climate regulation function, but less is on underground-soil organic carbon (SOC) sequestration and environmental stability. In this paper, we collected 180 soil samples from soil depths of 1 m (0–20, 20–40, 40–60, 60–80, 80–100 cm) in the farmland and neighbor shelterbelts in Songnen Plain, northeastern China. The sample plots covered six regions in the study area. SOC concentration and respiration decomposition rate, Q10 (temperature sensitivity), Hs (humidity sensitivity) were determined in the laboratory cultivation. Soil properties (N, P, K, electrical conductivity-EC, pH) and geographic-climate factors (multiple-year mean annual temperature and precipitation, MAT&MAP; temperature and precipitation during sampling month, MT &MP) were used to reveal the underlying reason for the changes in soil carbon sequestration. The results showed no significant difference in SOC respirational decomposition rate between farmland and shelterbelt forests but a 15.8% higher SOC concentration in shelterbelt forests (p < 0.05). The poplar shelterbelts reduced the Q10 value by 15.4% (p < 0.05), with deeper soils a more significant reduction in Q10. With soil moisture increases, both shelterbelt forests and farmland showed an obvious respiration pattern of first-increasing-then-decreasing. No significant Hs (linear gradients) differences were found in farmland and shelterbelt forests. Partitioning of the RDA ordination-based variation showed that SOC stability (Hs and Q10) of farmland was more affected by geo-climate. In contrast, the SOC stability of shelterbelt forests was greatly influenced by soil properties. Our findings manifest that the above-mentioned SOC changes can improve shelterbelt forest carbon sequestration function by prolonging the SOC lifespan in soil by at least 7% and SOC concentration by >15%. This should be included in the future to assess the underground soil carbon impact of Three-North shelterbelts in China and provide data supports for the estimation of similar forest stands in other parts of the world.