模拟氮沉降对杉木丛枝菌根真菌侵染率和球囊霉素的影响

杉木是我国南方重要的速生用材树种，同时南方面临着日益增强的大气氮沉降。尽管有大量的研究探索了氮沉降对杉木林的影响，但关于氮沉降对杉木与丛枝菌根真菌（arbuscular mycorrhizal fungi，AMF）共生关系影响的研究则较少报道。以10年生杉木为研究对象，模拟了不同氮沉降水平（N3：3 g N m^-2a^-1，N6：6 g N m^-2a^-1和Control：0 g N m^-2a^-1）对AMF侵染率和球囊霉素的影响。结果显示：在冬季，与对照相比，N3处理显著增加了AMF侵染率，N6处理显著增加易提取球囊霉素的含量，而氮沉降对总球囊霉素含量无显著影响。在春季，与对照相比，N3处理显著增加AMF侵染率，但是显著降低了易提取球囊霉素的含量。N6处理显著增加总球囊霉素的含量，但显著降低易提取球囊霉素的含量。相同氮添加情况下，春季的AMF侵染率显著低于冬季，而球囊霉素含量（易提取球囊霉素和总球囊霉素）均显著高于冬季的。土壤有效磷与AMF侵染率显著负相关，而与易提取球囊霉素和总球囊霉素含量显著正相关。侵染率与pH显著正相关，球囊霉素与pH显著负相关。本实验针对AMF侵染率和球囊霉素的含量对于氮沉降的响应做出探讨，对全面了解杉木与AMF之间的共生关系对氮沉降的响应及其机制提供了新的参考。

Effects of Nitrogen Deposition on Arbuscular Mycorrhizal Fungal Colonization and Glomalin-related Soil Protein of Chinese Fir

Chinese fir (Cunninghamia lanceolata) is an important fast-growing tree species in southern China. Simultaneously, nitrogen (N) deposition amounts are increasing in southern China. However, the effect of increasing atmospheric N deposition on arbuscular mycorrhizal fungal (AMF) colonization and glomalin-related soil protein (GRSP) in Chinese fir plantations remains poorly understood. Therefore, we conducted a N addition (N3: 3g N m^-2 a^-1, N6: 6g N m^-2 a^-1, and Control: 0 g N m^-2 a^-1) experiment in a ten-year-old Chinese fir plantation; AMF colonization and GRSP concentrations were evaluated in January and April, 2019. The results showed that in January, compared with the control treatment, the N3 treatment significantly increased the AMF colonization. The N6 treatment significantly increased the concentration of easily extractable GRSP (EE-GRSP) relative to the control treatment. Nitrogen deposition had no significant effect on concentrations of total GRSP (T-GRSP). In April, compared with the control treatment, the N3 treatment significantly increased the AMF colonization, but significantly reduced concentrations of EE-GRSP. The N6 treatment significantly increased the concentration of T-GRSP, but significantly reduced that of EE-GRSP. Under the same N addition rate, the AMF colonization in April was significantly lower than that in January, and the concentrations of EE-GRSP and T-GRSP showed a contrasting trend. Soil available phosphorus was significantly negatively correlated with AMF colonization but positively correlated with the concentrations of EE-GRSP and T-GRSP. AMF colonization, and concentrations of EE-GRSP and T-GRSP were significantly positively and negatively correlated with pH, respectively. Our results provided new insights in understanding the symbiotic relationship between Chinese fir and AMF under N deposition.