[Effects of Long-term Nitrogen Addition on the Carbon， Nitrogen， and Phosphorus Stoichiometry in Rhizosphere and Bulk Soils of Metasequoia glyptostroboides Plantations].

]. The basic physical and chemical properties， nutrient stoichiometric characteristics， enzyme activity， and microbial biomass of both rhizosphere and bulk soils were measured. The results indicated： ① Compared to that in N0， the overall carbon to nitrogen ratio in rhizosphere and bulk soils under all nitrogen addition treatments decreased significantly by 29.0% and 13.1%， respectively. In the N336 treatment， total nitrogen content and nitrogen to phosphorus ratio in rhizosphere soil significantly increased by 25.4% and 28.4%， respectively. The responses of soil organic carbon and total phosphorus contents and the carbon to phosphorus ratio to nitrogen addition were not significant across all treatments and in each individual treatment. ② The response directions of carbon， nitrogen， and phosphorus stoichiometric characteristics in rhizosphere and bulk soils to nitrogen addition were relatively consistent， but the response intensity in rhizosphere soil was greater. ③ Significant positive correlations were found among the organic carbon， total nitrogen， and total phosphorus contents in bulk soil， whereas only organic carbon and total nitrogen contents showed significant positive correlation in rhizosphere soil. Organic carbon content showed a significant positive correlation with stoichiometric ratios in both rhizosphere and bulk soils. ④ Microbial biomass and enzyme activity predominantly influenced the carbon， nitrogen， and phosphorus stoichiometric characteristics in bulk soil， whereas chemical properties such as pH， nitrate nitrogen， and available phosphorus contents were the primary regulators of these characteristics in rhizosphere soil. Overall， the responses of carbon， nitrogen， and phosphorus stoichiometric characteristics in rhizosphere and bulk soils to long-term nitrogen addition were relatively consistent but were regulated to varying degrees by soil chemical and microbial properties. This study deepens our understanding of the mechanisms and response patterns of rhizosphere and bulk soil carbon and nutrients to environmental changes， offering valuable scientific insights for advancing biogeochemical cycling models.