Experimental soil warming and cooling alters the partitioning of recent assimilates: evidence from a 14C-labelling study at the alpine treeline
- 525 Downloads
Despite concerns about climate change effects on ecosystems functioning, little is known on how plant assimilate partitioning changes with temperature. Particularly, large temperature effects might occur in cold ecosystems where critical processes are at their temperature limit. In this study, we tested temperature effects on carbon (C) assimilate partitioning in a field experiment at the alpine treeline. We warmed and cooled soils of microcosms planted with Pinus mugo or Leucanthemopsis alpina, achieving daily mean soil temperatures (3–10 cm depth) around 5.8, 12.7 and 19.2 °C in cooled, control and warmed soils. We pulse-labelled these systems with 14CO2 for one photoperiod and traced 14C over the successive 4 days. Plant net 14C uptake increased steadily with soil temperature. However, 14C amounts in fungal hyphae, soil microbial biomass, soil organic matter, and soil respiration showed a non-linear response to temperature. This non-linear pattern was particularly pronounced in P. mugo, with five times higher 14C activities in cooled compared to control soils, but no difference between warmed and control soil. Autoradiographic analysis of the spatial distribution of 14C in soils indicated that temperature effects on the vertical label distribution within soils depended on plant species. Our results show that plant growth, in particular root metabolism, is limited by low soil temperature. As a consequence, positive temperature effects on net C uptake may not be paralleled by similar changes in rhizodeposition. This has important implications for predictions of soil C storage, because rhizodeposits and plant biomass vary strongly in their residence times.
KeywordsCarbon partitioning C isotopes Climate change Leucanthemopsis alpina Pinus mugo
We acknowledge the financial support by the COST-SBF project C09.0130 in the framework of the COST Action FP0803.
Author contribution statement
PAN and FH formulated the idea and obtained the funding. AF carried out the field experiment and laboratory analysis. All authors contributed to study design, data analysis and interpretation. AF wrote the manuscript with input from PAN and FH
- Arft A, Walker M, Gurevitch J (1999) Responses of tundra plants to experimental warming: meta-analysis of the International tundra experiment. Ecol Monogr 69:491–511Google Scholar
- IPCC (2013) Summary for policymakers. In: Stocker TF, Qin D, Plattner G-K et al. (eds) Climate change 2013: The physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change. Cambridge University Press, CambridgeGoogle Scholar
- Moser M (1958) Influence of low temperature on growth and functioning of the higher fungi, with special reference to mycorrhiza. Sydowia 12:386–399Google Scholar
- Pannatier-Graf E, Thimonier A, Schmitt M et al (2011) A decade of monitoring at swiss long-term forest ecosystem research (LWF) sites: can we observe trends in atmospheric acid deposition and in soil solution acidity? Environ Monit Assess 174:3–30. doi: 10.1007/s10661-010-1754-3 CrossRefGoogle Scholar
- Stitt M, Huber S, Kerr P (1987) Control of photosynthetic sucrose formation. In: Hatch M, Boardman N (eds) The Biochemistry of Plants, vol 10., Academic, San Diego, pp 327–409Google Scholar
- Stocker TF, Qin D, Plattner G-K (eds) (2013) IPCC 2013: Summary for policymakers. In: climate change 2013: The physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change. Cambridge University Press, CambridgeGoogle Scholar
- Walthert L, Blaser P, Lüscher P et al (2003) Langfristige Waldökosystem-Forschung LWF in der Schweiz Kernprojekt Bodenmatrix Ergebnisse der ersten Erhebung 1994–1999. In: Eidgenössische Forschungsanstalt (WSL). http://e-collection.ethbib.ethz.ch/cgi-bin/show.pl?type=bericht&nr=276