title: Reduced compensatory effects explain the nitrogen-mediated reduction in stability of an alpine meadow on the Tibetan Plateau.
abstract: Many ecosystems are facing strong perturbations such as nitrogen (N) fertilization, which can greatly alter ecosystem stability via different mechanisms. Understanding such mechanisms is critical for predicting how ecosystems will function in the face of global changes. We examined how 8 yr of N fertilization with different N rates (no N addition or N addition at a low, medium or high rate) and different forms of N (ammonium, nitrate or ammonium nitrate) affected the temporal stability of the aboveground biomass of an alpine meadow on the Tibetan Plateau, and tested four mechanisms (diversity effect, mean-variance scaling, compensatory dynamics and dominance effect) that may alter stability. Compared with the control (no N addition), a high N rate did not affect the diversity effect, the mean-variance scaling or the dominance effect, but significantly decreased compensatory dynamics among species and functional groups, which contributed to the reduction in community stability of the alpine meadow. The form of N did not affect any of the four mechanisms and thus did not affect community stability. A high N rate can change community stability by altering compensatory dynamics, whereas the form of N may not have an effect.
authors: Key Laboratory of Ecosystem Network Observation and Modelling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
authors: Ming-Hua
authors: MH
authors: Song
authors: School of Nature Conservation, Beijing Forestry University, Beijing, 100083, China.
authors: Fei-Hai
authors: FH
authors: Yu
mesh_terms: D005308:Fertilizers; D065948:Grassland; D016014:Linear Models; D009584:Nitrogen / Q000494:pharmacology*; D013045:Species Specificity; D018609:Tibet
chemical_list: D005308:Fertilizers; D009584:Nitrogen
keywords: N fertilization; compensatory effect; dominance effect; long-term experiment; mean-variance scaling; nitrogen (N) chemical form; richness; temporal stability