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Estimating tree canopy water use via xylem sapflow in an old Norway spruce forest and a comparison with simulation-based canopy transpiration estimates

Title data

Köstner, Barbara ; Falge, Eva ; Alsheimer, Martina ; Geyer, Ralf ; Tenhunen, John:
Estimating tree canopy water use via xylem sapflow in an old Norway spruce forest and a comparison with simulation-based canopy transpiration estimates.
In: Annals of Forest Science. Vol. 55 (1998) Issue 1-2 . - pp. 125-139.
ISSN 1297-966X
DOI: https://doi.org/10.1051/forest:19980108

Abstract in another language

Tree xylem sapflow rates of 140-year-old Norway spruce (Picea abies) were scaled to the stand level and compared to canopy transpiration predicted by the stand gas exchange model STANDFLUX. Variation in sapflux densities between individual sensors was high (coefficient of variance = 0.4) and included both variation within and between trees, but it was not different between two applied sapflow methodologies (radial flowmeter according to Granier, variable heating tissue heat balance method according to Cermák and Kucera). During the morning, a time-lag of typically 2 h elapsed between sapflow (Ef) and predicted canopy transpiration rate (Ep). During this time total water use was as high as 0.3 mm, which was less than the estimated capacity of easily available water in the tree canopy (0.45 mm, on average 14 l per tree). Canopy conductance derived from stand sapflow rates (gf) and from STANDFLUX (gp) was in the same range (gtmax: 10 mm s-1), but a stronger decline with increasing vapor pressure deficit of the air (D) was observed for gf as compared to gp with current model parameterization. Tree water uptake measured by xylem sapflow was higher during spring and somewhat lower during summer compared with Ep. Seasonal sums of transpiration from April to October amounted 108 mm season-1 and 103 mm seasong-1 for Ef and Ep, respectively. Estimated tree water uptake during night increased with D up to 0.5 mm per dark period (on average 16 l per tree) which was 10-140% of total daily flux. Because this flow rate did not increase with further increases in D during night, it is concluded that it reflects the refilling of easily exchangeable water in the trees rather than a rate of night transpiration.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER7188
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Biology > Chair Plant Ecology
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Biology
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 11 Sep 2015 06:35
Last Modified: 11 Sep 2015 06:35
URI: https://eref.uni-bayreuth.de/id/eprint/19380