Under the guidance of Associate Researcher Zheng Mianhai, Dr. Fan Linjie from the South China Botanical Garden of the Chinese Academy of Sciences conducted a study utilizing the long-term nitrogen and phosphorus addition experimental platform at the Heshan Forest Ecosystem National Field Scientific Observation and Research Station in Guangdong Province. The study discovered that long-term nitrogen and phosphorus addition reduce the accumulation of microbial necromass carbon in the soil of subtropical forests. These findings were recently published in the journal Global Change Biology.
The response mechanism of microbial necromass carbon in different soil layers of leguminous and non-leguminous plantations to nitrogen and phosphorus additions was investigated. Participants provided images.
Two typical subtropical plantations, Acacia mangium (leguminous) and Eucalyptus urophylla (non-leguminous), were selected for the study to explore the variation of soil microbial necromass carbon and its response mechanisms to long-term nitrogen and phosphorus additions. After long-term (12 years) nitrogen and phosphorus addition treatments, differential responses in microbial necromass carbon concentrations in different soil layers were observed. There was no significant effect of long-term nitrogen and phosphorus additions on microbial necromass carbon concentration in the surface soil layer (0-20 cm).
Further findings revealed that microbial necromass carbon in the deep soil layer was mainly influenced by microbial properties and mineral protection, while in the surface soil layer, the contributions of plant carbon inputs and mineral protection were more significant. For the deep soil layer, phosphorus addition led to a decrease in microbial turnover and calcium-bound carbon concentration, thus reducing the accumulation of microbial necromass carbon. Although microbial turnover and calcium-bound carbon in the surface soil layer also decreased, the accelerated decomposition of surface litter and increased microbial biomass might compensate for the decrease in microbial necromass carbon in the surface soil layer, resulting in no significant change in microbial necromass carbon concentration.
The study suggests that long-term atmospheric nitrogen deposition and soil phosphorus deficiency may affect the stability of soil carbon in the lower layers of subtropical forests. Future research needs to focus more on the stability of organic carbon in different soil layers of forests, especially in the lower layers, and its driving mechanisms, which are crucial for accurately understanding and predicting the soil carbon sequestration potential of subtropical forests.
Related paper information: https://doi.org/10.1111/gcb.17210
