Abiotic and biotic controls of soil dissolved organic nitrogen along a precipitation gradient on the Tibetan plateau

• Published in: Plant and soil 2021-02, Vol.459 (1-2), p.65-78
• Main Authors: Jiang, Lili, Wang, Shiping, Pang, Zhe, Wang, Changshun, Meng, Fandong, Lan, Zhichun, Zhou, Xiaoqi, Li, Yaoming, Zhang, Zhenhua, Luo, Caiyun, Jones, Davey L., Rui, Yichao, Wang, Yanfen
• Format: Article
• Language: English
• Subjects: Alpine ecosystems; Alpine environments; Analysis; Annual precipitation; Aquatic ecosystems; Biological activity; Biomass; Biomedical and Life Sciences; Climate change; Climate prediction; Deserts; Dissolved organic nitrogen; Ecology; Ecosystem components; Ecosystems; Grasslands; Life Sciences; Meadows; Microbial activity; Microorganisms; Nitrogen; Nitrogen content; Organic nitrogen; Organic soils; Phosphorus; Plant biomass; Plant Physiology; Plant Sciences; Precipitation; Precipitation (Chemistry); Regular Article; Soil moisture; Soil Science & Conservation; Soils; Steppes; Vegetation type
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-020-04613-1

Background and aims Dissolved organic nitrogen (DON) has been increasingly recognized as a crucial component of the terrestrial nitrogen (N) cycle that regulates the ecosystem feedback to climate change. Yet, little information is available about the factors that control soil DON in the alpine ecosystems of the Tibetan Plateau, a region that is extremely sensitive to climate change. Methods Here, we examined the relationship between DON and climate, plant, and soil attributes along a precipitation gradient in five alpine ecosystems (alpine wetland, alpine meadow, alpine shrub, alpine steppe, and alpine desert) across 20 sites that were up to 4000 km apart on the Tibetan Plateau. Results Results showed that soil DON concentration varied significantly across these alpine ecosystems, and had a positive relationship with mean annual precipitation. Belowground biomass, soil moisture, micro biomass carbon (MBC), and soil total phosphorus (TP) explained 84% of the variation in DON concentrations. The percentage of DON in soil total dissolved N (TDN) varied with vegetation type, with the lowest percentage observed in the alpine meadow (52%) and the highest in the alpine desert (77%), indicating the slow turnover of DON into inorganic N in systems with low litter input and microbial activity. Conclusions Precipitation and plant biomass input determine the concentration and turnover of soil DON on the Tibetan Plateau. A warmer and wetter climate that has been predicted for the Tibetan grasslands may lead to a larger and more active DON pool.