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Responses of two provenances of Fagus sylvatica seedlings to a combination of four temperature and two CO 2 treatments during their first growing season: gas exchange of leaves and roots
Author(s) -
LEVERENZ J. W.,
BRUHN D.,
SAXE H.
Publication year - 1999
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.1999.00541.x
Subject(s) - beech , fagus sylvatica , transpiration , stomatal conductance , photosynthesis , horticulture , botany , chemistry , zoology , biology
Physiological responses of two provenances of European beech ( Fagus sylvatica ) were studied in seedlings grown at two [CO 2 ] in combination with four temperature treatments. For the local Danish provenance, the average effect of elevated [CO 2 ] during growth was to increase light‐saturated net photosynthesis ( A n ) and instantaneous water‐use efficiency or transpiration efficiency (ITE). These increases were strongly related to the temperature treatment. Stomatal conductance ( g s ) was reduced in seedlings in high [CO 2 ], but there was no statistically significant effect of temperature treatment. Stomatal conductance was 13–26% lower at elevated [CO 2 ] and ITE was 89–156% higher, depending on growth temperature. The effects of [CO 2 ] on A n were considerably larger than those shown for many other woody species, but similar to those in other studies on European beech. The absolute value of A n for a Romanian provenance of beech was 5–18% lower than in the Danish provenance at low [CO 2 ] and 14–26% lower at high [CO 2 ]. There was no statistically significant interaction between the provenances and [CO 2 ], or between provenance and temperature. A model of the response of A n to [CO 2 ] at different temperatures gave predictions close to the measured results, except at the lowest temperature treatment where the model over‐predicted the effect of elevated [CO 2 ]. This and measurements of A n made at a common, low [CO 2 ] indicated a down‐regulation of photosynthesis in the lowest temperature treatment at high [CO 2 ]. Root plus soil respiration on a whole‐tree basis ( R tr ) was increased by elevated [CO 2 ] at all but the lowest temperature, but no effect was seen of [CO 2 ] on root respiration per unit root d. wt. Mean R tr on any given date was significantly correlated with A n , except at the lowest temperature treatment. It is hypothesized that low temperature limited the ability of the roots to use photosynthates resulting in a feedback inhibition of A n when elevated [CO 2 ] was combined with low temperature.