Present address: Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, Jilin 130024, China.
Environmental and physiological controls on the carbon isotope composition of CO2 respired by leaves and roots of a C3 woody legume (Prosopis velutina) and a C4 perennial grass (Sporobolus wrightii)
Article first published online: 24 OCT 2011
© 2011 Blackwell Publishing Ltd
Plant, Cell & Environment
Volume 35, Issue 3, pages 567–577, March 2012
How to Cite
SUN, W., RESCO, V. and WILLIAMS, D. G. (2012), Environmental and physiological controls on the carbon isotope composition of CO2 respired by leaves and roots of a C3 woody legume (Prosopis velutina) and a C4 perennial grass (Sporobolus wrightii). Plant, Cell & Environment, 35: 567–577. doi: 10.1111/j.1365-3040.2011.02436.x
- Issue published online: 17 JAN 2012
- Article first published online: 24 OCT 2011
- Accepted manuscript online: 29 SEP 2011 05:33AM EST
- Received 10 March 2011; received in revised form 24 September 2011; accepted for publication 25 September 2011
- non-structural carbohydrate;
Accurate estimates of the δ13C value of CO2 respired from roots (δ13CR_root) and leaves (δ13CR_leaf) are important for tracing and understanding changes in C fluxes at the ecosystem scale. Yet the mechanisms underlying temporal variation in these isotopic signals are not fully resolved. We measured δ13CR_leaf, δ13CR_root, and the δ13C values and concentrations of glucose and sucrose in leaves and roots in the C4 grass Sporobolus wrightii and the C3 tree Prosopis velutina in a savanna ecosystem in southeastern Arizona, USA. Night-time variation in δ13CR_leaf of up to 4.6 ± 0.6‰ in S. wrightii and 3.0 ± 0.6‰ in P. velutina were correlated with shifts in leaf sucrose concentration, but not with changes in δ13C values of these respiratory substrates. Strong positive correlations between δ13CR_root and root glucose δ13C values in P. velutina suggest large diel changes in δ13CR_root (were up to 3.9‰) influenced by short-term changes in δ13C of leaf-derived phloem C. No diel variation in δ13CR_root was observed in S. wrightii. Our findings show that short-term changes in δ13CR_leaf and δ13CR_root were both related to substrate isotope composition and concentration. Changes in substrate limitation or demand for biosynthesis may largely control short-term variation in the δ13C of respired CO2 in these species.