Soil properties and substrate quality determine the priming of soil organic carbon during vegetation succession

PurposeThere is an increasing recognition that the priming effect (PE) induced by fresh organic matter (FOM) may greatly influence soil organic carbon (SOC) dynamics. However, the patterns of PE induced by substrates with different quality on soils from vegetation succession, as well as the underlying mechanisms, are still unclear.MethodsWe conducted a field investigation to explore the changes in soil properties and SOC stocks along a secondary vegetation succession (cropland → shrubland → forest); then, we examined the patterns of PE by incubating FOMs with soils from the different succession stages. The added FOMs included 13C-labeled glucose (GLU) as well as labile organic matter (LOM) and recalcitrant organic matter (ROM) extracted from 13C-labeled maize leaves.ResultsIncreases in SOC stock and changes in soil properties were detected during the process of vegetation succession. FOMs with contrasting quality caused PEs in different magnitudes, with a higher PE generated after the GLU and LOM treatments compared with ROM. We also detected a higher soil fungi/bacteria (F/B) with ROM than the GLU and LOM treatment. Under a given substrate treatment, PE was generally higher on cropland soil than shrubland and forest soil. The variations of PE among succession stages were negatively correlated with soil aggregate stability, total inorganic nitrogen, and available phosphorus and positively correlated with pH and F/B ratio.ConclusionsSoil properties and substrate quality determine the PE in soils from vegetation succession. The PE might be one of the potential mechanisms underlying soil C dynamics during the vegetation succession.