Little is known about the response mechanisms of individual plants in alpine regions to N deposition. We conducted a field experiment with three treatments, including 0 kg N ha-1 year-1 (CK), 8 kg N ha-1 year-1 (Low N), and 72 kg N ha-1 year-1 (High N) established to simulate N deposition in alpine meadows of the Qinghai-Tibetan plateau. The results showed that responses of alpine plants were species-specific under N deposition. Compared with grass species (Agropyron cristatum) and forb species (Thalictrum aquilegifolium), the sedge species (Carex melanantha) was much more sensitive to N deposition; a lower N load (8 kg N ha-1year-1) can cause a negative effect on its photosynthesis and productivity. Additionally, N deposition can promote plant N uptake and significantly decreased the C/N ratio. High N deposition inhibited the photosynthesis and growth of the forb species Thalictrum aquilegifolium and sedge species Carex melanantha. In all three functional types of herbage species, the grass species A. cristatum tended to show a much higher photosynthetic capacity and better growth potential; thus, suggesting that grass species A. cristatum will be a more adaptive alpine plants under N deposition. Our findings suggested that plant photosynthetic responses to N deposition were species-specific, low N deposition was not beneficial for all herbage species, and N deposition may change plant composition by the differential photosynthetic responses among species in alpine grassland. Plant composition shifts to grass-dominance in alpine regions might be attributed to a much higher photosynthetic potential and N use efficiency of grass species.
Audio/Video, Conference Presentation, SER2019
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Society for Ecological Restoration