Mr Jiguang Feng1, Dr. Biao Zhu1
1Peking University, , China
The inputs of fresh carbon will alter the decomposition of soil organic matter (SOM), which is known as priming effect (PE). Priming effect plays an important role in regulating SOM decomposition and soil carbon storage. Increasing nitrogen (N) and phosphorus (P) inputs and deposition induced by anthropogenic activities have largely increased the availability of soil nutrients, and thus should affect PE. Although many studies have investigated the effects of nutrient enrichment on PE, the general patterns at global scale remain unclear. Here, we compiled available data on PE under nutrient enrichment from primary literatures to examine how nutrient enrichment regulates PE. Results showed that, across all studies, N enrichment and combined N and P enrichment significantly decreased PE (p < 0.05), whereas P enrichment had minor effect on PE (p > 0.05). Specifically, N enrichment effects on PE varied among ecosystem types, with significant negative effect occurring in grassland, boreal, temperate and tropical forest (p < 0.05). Meanwhile, the effects of nutrient enrichment on PE generally decreased with initial soil nutrient status (organic carbon, total nitrogen and phosphorus), indicating that these factors potentially regulate nutrient effects on PE. In addition, the effects of N and combined N and P enrichment on PE were regulated by substrate type, with significant negative nutrient effects in substrates not containing the mineral nutrient added. Combinations of microbial nutrient mining hypothesis and microbial stoichiometric decomposition hypothesis can explain the observed relationships across all ecosystems. Collectively, our findings imply that N deposition might be beneficial to soil carbon storage via suppressing PE, and highlight the need for further field in situ studies investigating nutrient enrichment effects on PE.
Biography: Jiguang Feng is a PhD student of College of Urban and Environmental Sciences, Peking University. His research interests are nutrient limitation in tropical forest, soil carbon cycling under global change, and soil microbial ecology.