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Inter-annual and seasonal variations of energy and water vapour above Pinus sylvestris in the Siberian middle taiga

Tchebakova, NM; Kolle, O; Zolotoukhine, D; Arneth, Almut LU ; Styles, JM; Vygodskaya, N; Schulze, ED; Shibistova, O and Lloyd, J (2002) In Tellus. Series B: Chemical and Physical Meteorology 54B(5). p.537-551
Abstract
Long-term eddy covariance measurements of energy and water fluxes and associated climatic parameters were carried out above a Scots pine (Pinus sylvestris) forest in the middle taiga zone of Central Siberia. Data from June 1998 through October 2000 are presented. With the exception of winter 1998/1999, data collection over this period were more or less continuous. A distinct seasonality in surface energy exchange characteristics was observed in all years. In early spring in the absence of physiological activity by the vegetation, about 80% of the net radiation was partitioned for sensible heat, resulting in Bowen ratios, β, as high as 8. In the 1–2 wk period associated with onset of photosynthesis in spring, evaporation rates increased... (More)
Long-term eddy covariance measurements of energy and water fluxes and associated climatic parameters were carried out above a Scots pine (Pinus sylvestris) forest in the middle taiga zone of Central Siberia. Data from June 1998 through October 2000 are presented. With the exception of winter 1998/1999, data collection over this period were more or less continuous. A distinct seasonality in surface energy exchange characteristics was observed in all years. In early spring in the absence of physiological activity by the vegetation, about 80% of the net radiation was partitioned for sensible heat, resulting in Bowen ratios, β, as high as 8. In the 1–2 wk period associated with onset of photosynthesis in spring, evaporation rates increased rapidly and β rapidly dropped. However, even during summer months, sensible heat fluxes typically exceeded latent heat fluxes and β remained above 2.0. Observed daily evaporation rates varied between 0.5–1.0 mm d-1 in spring and autumn and 1.5–2 mm d-1 in midsummer. The overall average for the three growing seasons examined was 1.25 mm d-1. Precipitation was on average 230 mm for the growing period, with evaporation over the same time being about 190 mm for both 1999 and 2000. This represented only about 35% of the equilibrium evaporation rate. There was typically a positive hydrological balance of 40 mm for the growing season as a whole. However, in all three years examined, evaporation exceeded precipitation totals by 20–40 mm in at least one calendar month during summer.



During the growing season, daily averaged surface conductances varied between 0.15 and 0.20 mol m-2 s-1 (3–4.5 mm s-1) in dry or cool months and 0.30–0.35 mol m-2 s-1 (6.5–8 mm s-1) in moist and warm months. Despite a negative hydrological balance during midsummer, there was little evidence for reduced canopy conductances in response to soil water deficits. This may have been the consequence of roots accessing water from within or just above a perched water table, located at about 2 m depth. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
in
Tellus. Series B: Chemical and Physical Meteorology
volume
54B
issue
5
pages
537 - 551
publisher
Taylor & Francis
external identifiers
  • scopus:0036868481
ISSN
0280-6509
DOI
10.1034/j.1600-0889.2002.01337.x
language
English
LU publication?
no
id
af8088c0-fc67-49f4-b147-a4927d2d9018 (old id 590209)
date added to LUP
2007-11-16 09:08:22
date last changed
2017-01-01 07:09:44
@article{af8088c0-fc67-49f4-b147-a4927d2d9018,
  abstract     = {Long-term eddy covariance measurements of energy and water fluxes and associated climatic parameters were carried out above a Scots pine (Pinus sylvestris) forest in the middle taiga zone of Central Siberia. Data from June 1998 through October 2000 are presented. With the exception of winter 1998/1999, data collection over this period were more or less continuous. A distinct seasonality in surface energy exchange characteristics was observed in all years. In early spring in the absence of physiological activity by the vegetation, about 80% of the net radiation was partitioned for sensible heat, resulting in Bowen ratios, β, as high as 8. In the 1–2 wk period associated with onset of photosynthesis in spring, evaporation rates increased rapidly and β rapidly dropped. However, even during summer months, sensible heat fluxes typically exceeded latent heat fluxes and β remained above 2.0. Observed daily evaporation rates varied between 0.5–1.0 mm d-1 in spring and autumn and 1.5–2 mm d-1 in midsummer. The overall average for the three growing seasons examined was 1.25 mm d-1. Precipitation was on average 230 mm for the growing period, with evaporation over the same time being about 190 mm for both 1999 and 2000. This represented only about 35% of the equilibrium evaporation rate. There was typically a positive hydrological balance of 40 mm for the growing season as a whole. However, in all three years examined, evaporation exceeded precipitation totals by 20–40 mm in at least one calendar month during summer.<br/><br>
<br/><br>
During the growing season, daily averaged surface conductances varied between 0.15 and 0.20 mol m-2 s-1 (3–4.5 mm s-1) in dry or cool months and 0.30–0.35 mol m-2 s-1 (6.5–8 mm s-1) in moist and warm months. Despite a negative hydrological balance during midsummer, there was little evidence for reduced canopy conductances in response to soil water deficits. This may have been the consequence of roots accessing water from within or just above a perched water table, located at about 2 m depth.},
  author       = {Tchebakova, NM and Kolle, O and Zolotoukhine, D and Arneth, Almut and Styles, JM and Vygodskaya, N and Schulze, ED and Shibistova, O and Lloyd, J},
  issn         = {0280-6509},
  language     = {eng},
  number       = {5},
  pages        = {537--551},
  publisher    = {Taylor & Francis},
  series       = {Tellus. Series B: Chemical and Physical Meteorology},
  title        = {Inter-annual and seasonal variations of energy and water vapour above Pinus sylvestris in the Siberian middle taiga},
  url          = {http://dx.doi.org/10.1034/j.1600-0889.2002.01337.x},
  volume       = {54B},
  year         = {2002},
}