AUTHOR=Yu Qinghui , Zhang Zixu , He Yuan , Hao Ming , Wang Guifang , Dun Xingjian , Wu Qicong , Gao Peng TITLE=Secondary shrubs promoted the priming effect by increasing soil particle organic carbon mineralization JOURNAL=Frontiers in Forests and Global Change VOLUME=Volume 6 - 2023 YEAR=2023 URL=https://www.frontiersin.org/journals/forests-and-global-change/articles/10.3389/ffgc.2023.1288259 DOI=10.3389/ffgc.2023.1288259 ISSN=2624-893X ABSTRACT=Inputs of additional organic matter to the soil will accelerate or inhibit the decomposition of soil organic carbon (SOC), resulting in a priming effect (PE), which is a key mechanism affecting soil carbon (C) cycling. The impact mechanism of changes in soil properties on the PE is still unclear after vegetation restoration; in particular, the contribution of C pools with different turnover rates to the PE has not been distinguished and quantified. We separated the soil particulate organic C (POC) and mineralassociated organic C (MAOC) fractions during incubation and then studied their changes in relation to the soil properties and PE. This was done to explore the influence mechanism of vegetation restoration on the PE and the contribution of mineralization of C pools with different turnover rates to the PE during the restoration process. In this study, the secondary shrub (SB) (Vitex negundo var. heterophylla) formed by the enclosure of barren grassland was selected as the research object, and the barren grassland (GL) was taken as the control. Equal amounts of 13 C-labeled glucose were added to the topsoil for a 45-day incubation experiment to measure the PE. Moreover, soil samples were destructively sampled to explore the changes in POC and MAOC fractions during incubation. After 45 days of incubation, most of the new C formed by glucose flowed to MAOC, with 95.45% in SB soil and 92.29% in GL soil. In the experiment, all soils showed a positive PE. The PE, POC mineralization and MAOC accumulation were higher in SB soil than in GL soil. During incubation, the mineralization of POC was positively correlated with the PE and made a major contribution to the PE. Partial correlation analysis showed that after vegetation restoration, SB further promoted the mineralization of POC by increasing the soil moisture, fungal diversity and necromass C of bacteria, which led to an increase in PE. The difference between POC and MAOC fraction mineralization during incubation provided valuable information, which helped us to deepen our understanding of the impact of secondary shrubs on the PE and soil C cycling.