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Pinus taeda
Acclimation of leaf hydraulic conductance and stomatal conductance of Pinus taeda (loblolly pine) to long-term growth in elevated CO2 (free-air CO2 enrichment) and N-fertilization.
by Domec J.-C.., Palmroth S., Ward E., Maier C. A., Therezien M., Oren R. (2009)
Mathieu Therezien, Duke University, Civil and Environmental Engineering,
JEAN-CHRISTOPHE DOMEC 1,3, SARI PALMROTH 1, ERIC WARD 1, CHRIS A. MAIER 4, Mathieu THÉRÉZIEN 2, RAM OREN 1
1 Nicholas School of the Environment and Earth Sciences, Box 90328,
2 Department of Civil and Environmental Engineering, Box 90287, Duke University, Durham, NC 27708, USA,
3 Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27695, USA
4 Southern Research Station, USDA Forest Service, 3041 Cornwallis Road, Research Triangle Park, NC 27709, USA
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in Plant, Cell Environ. 32: 1500-1512 –
Acclimation_of_leaf_hydraulic_conductanc.pdf
ABSTRACT
We investigated how leaf hydraulic conductance (Kleaf) of loblolly pine trees is influenced by soil nitrogen amendment (N) in stands subjected to ambient or elevated CO2 concentrations (CO2a and CO2e, respectively).
We also examined how Kleaf varies with changes in reference leaf water potential (Yleaf-ref) and stomatal conductance (gs-ref) calculated at vapour pressure deficit, D of 1 kPa.
We detected significant reductions in Kleaf caused by N and CO2e, but neither treat- ment affected pre-dawn or midday Yleaf. We also detected a significant CO2 e-induced reduction in gs-ref and Yleaf-ref.
Among treatments, the sensitivity of Kleaf to Yleaf was directly related to a reference Kleaf (Kleaf-ref computed at Yleaf-ref). This liquid-phase response was reflected in a similar gas-phase response, with gs sensitivity to D proportional to gs-ref.
Because leaves represented a substantial component of the whole-tree conductance, reduction in Kleaf under CO2e affected whole-tree water use by inducing a decline in gs-ref.
The consequences of the acclimation of leaves to the treatments were:
(1) trees growing under CO2e controlled morning leaf water status less than CO2a trees resulting in a higher diurnal loss of Kleaf;
(2) the effect of CO2e on gs-ref was manifested only during times of high soil moisture.
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