No stimulation in root production in response to 4 years of in situ CO2 enrichment at the Swiss treeline
Article first published online: 17 DEC 2007
© 2007 The Authors
Volume 22, Issue 2, pages 348–358, April 2008
How to Cite
Handa, I. T., Hagedorn, F. and Hättenschwiler, S. (2008), No stimulation in root production in response to 4 years of in situ CO2 enrichment at the Swiss treeline. Functional Ecology, 22: 348–358. doi: 10.1111/j.1365-2435.2007.01372.x
- Issue published online: 17 DEC 2007
- Article first published online: 17 DEC 2007
- Received 18 July 2007; accepted 16 November 2007Handling Editor: Ken Thompson
- Larix decidua;
- Pinus uncinata;
- ericaceous dwarf shrubs;
- fine roots;
- stable carbon isotope;
- elevated CO2;
- 1Plants are frequently observed to increase carbon allocation to below-ground sinks and particularly, to accelerate fine root turnover in response to rising atmospheric CO2 concentration. While these strong below-ground responses have predominantly been observed in rapidly expanding systems, late successional plant communities have rarely been studied.
- 2In an ongoing free air CO2 enrichment (FACE) experiment, we assessed below-ground responses to elevated CO2 after 4 years, in a treeline ecosystem in the Swiss Central Alps (2180 m a.s.l.) dominated by a late successional ericaceous dwarf shrub community (Vaccinium myrtillus, V. uliginosum, Empetrum hermaphroditum), and a sparse overstorey of 30-year-old Larix decidua and Pinus uncinata trees. Measurements included quantification of fine root growth using ingrowth root cores and parallel standing crop harvests and decomposition of roots using litter bags.
- 3Elevated CO2 did not stimulate root growth of the treated vegetation (although some significant above-ground growth responses were observed), nor did altered root decomposition occur. Root quality measurements indicated that elevated CO2 resulted in significantly higher starch concentrations, but no change in N concentration, or root dehydrogenase activity.
- 4The use of the stable isotope δ13C permitted us to trace the new carbon entering the system through our CO2 enrichment treatment. We observed that only c. 30% of new root biomass (< 2 mm) was formed by new carbon indicating a rather slow root turnover in this system.
- 5Our data show that fine root growth may be much less stimulated by elevated CO2 in systems with late successional elements than has been reported in ecosystems with a rapidly expanding plant community biomass.