In situ effects of elevated CO 2 on the carbon and nitrogen status of alpine plants

• Published in: Functional Ecology
• Main Authors: SCHÄPPI, B., KÖRNER, CH.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1997
• Subjects: Poa alpina
• Online Access: http://dx.doi.org/10.1046/j.1365-2435.1997.00084.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1365-2435.1997.00084.x; https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2435.1997.00084.x

1. The effect of elevated CO 2 on tissue composition in an alpine grassland (Swiss Central Alps, 2500m) under both natural and increased nutrient supply (NPK) is summarized. 2. During 3 years of CO 2 enrichment the concentration of total non‐structural carbohydrates (TNC) in leaves increased by 32% in Leontodon helveticus (largely sugar) and by 56% in Trifolium alpinum (largely starch) but did not change significantly in the dominant sedge Carex curvula and in Poa alpina , currently a rare species at this site. 3. Enhanced mineral nutrient supply (unlike elevated CO 2 ) greatly stimulated growth but did not reduce the CO 2 ‐induced TNC accumulation. 4. Under elevated CO 2 nitrogen concentrations (per g TNC‐free dry matter) of green leaves decreased in Leontodon (–21%) and in Trifolium (–24%) but not or only slightly in Carex and in Poa . NPK addition compensated this CO 2 effect on nitrogen concentration in Trifolium but not in the other species. 5. In below‐ground tissue neither TNC nor nitrogen concentration responded to CO 2 fertilization. 6. The nitrogen pool per unit land area at peak season biomass remained unaffected by the CO 2 treatment. 7. Overall our results suggest that the late successional dominant sedge Carex curvula remains unaffected by elevated CO 2 , independently of mineral nutrient supply, whereas the co‐dominant and sub‐dominant forbs Leontodon helveticus and Trifolium alpinum show both an increase of TNC as well as N depletion under elevated CO 2 . 8. None of these changes in active plant tissue translate into compositional changes in naturally senesced litter suggesting caution with predictions of CO 2 effects on decomposition based on data from green plant material.