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| Titel |
The sensitivity of stand-scale photosynthesis and transpiration to changes in atmospheric CO2 concentration and climate |
| VerfasserIn |
B. Kruijt, C. Barton, A. Rey, P. G. Jarvis |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 3, no. 1 ; Nr. 3, no. 1, S.55-69 |
| Datensatznummer |
250000755
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| Publikation (Nr.) |
 copernicus.org/hess-3-55-1999.pdf |
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| Zusammenfassung |
The 3-dimensional forest model MAESTRO was used to simulate
daily and annual photosynthesis and transpiration fluxes of forest stands and the
sensitivity of these fluxes to potential changes in atmospheric CO2
concentration ([CO2]), temperature, water stress and phenology. The effects of
possible feed-backs from increased leaf area and limitations to leaf nutrition were
simulated by imposing changes in leaf area and nitrogen content. Two different tree
species were considered: Picea sitchensis (Bong.) Carr., a conifer with long
needle longevity and large leaf area, and Betula pendula Roth., a broad-leaved
deciduous species with an open canopy and small leaf area.
Canopy photosynthetic
production in trees was predicted to increase with atmospheric [CO2] and length
of the growing season and to decrease with increased water stress. Associated increases in
leaf area increased production further only in the B. pendula canopy, where the
original leaf area was relatively small. Assumed limitations in N uptake affected
B. pendula more than P. sitchensis. The effect of increased temperature was
shown to depend on leaf area and nitrogen content. The different sensitivities of the two
species were related to their very different canopy structure. Increased [CO2]
reduced transpiration, but larger leaf area, early leaf growth, and higher temperature all
led to increased water use. These effects were limited by feedbacks from soil water
stress. The simulations suggest that, with the projected climate change, there is some
increase in stand annual `water use efficiency', but the actual water losses to the
atmosphere may not always decrease. |
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