Terricolous mosses and epilithic mosses are often used to indicate atmospheric nitrogen (N) deposition, while terricolous mosses also absorb N from soils. How to use N isotopes (δ15N) of terricolous mosses to trace the levels and sources of atmospheric N deposition accurately is an urgent problem to resolve. Based on the N contents (Nmoss) and isotopes (δ15Nmoss) of terricolous and epilithic mosses collected in Mount Qilian in 2022, we established a bottom-up method to calculate local atmospheric N deposition levels and source contributions. No significant difference was found in Nmoss between soils and bare rocks, whil terricolous mosses had significantly higher δ15Nmoss than epilithic mosses. Thus, the effects of soil N sources on δ15Nmoss of terricolous mosses should be excluded before they are used to tuace emission surrces of atmospheric N deposition. The flux of total inorganic N deposition in Mount Qilian was 15.0 ± 2.3 kg N ha−1 year−1, with nitrate-N deposition being dominant. According to analyses of emission sources, it was volatilization-related ammonia (61.9% ± 19.8%; mainly from fertilizer application and wastes) rather than combustion-related ammonia (38.1% ± 19.8%) that dominated atmospheric ammonium-N deposition. It was fossil fuel N oxides (51.5% ± 19.6%; mainly from oil and coal combustion) rather than non-fossil fuel N oxides (48.5% ± 19.6%; mainly from biomass burning and microbial N cycles) that dominated nitrate-N deposition in this region. The Mount Qilian region holds an important position as a crucial ecological barrier in western China. Therefore, it is important to reduce reactive N emissions based on the above source apportionments to protect the fragile ecosystems of Mount Qilian.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |