Abstract
| Original language | English |
|---|---|
| Publication status | Published - 2013 |
| Event | EGU General Assembly 2013 - Vienna, Austria Duration: 7 Apr 2013 → 12 Apr 2013 |
Conference
| Conference | EGU General Assembly 2013 |
|---|---|
| Country | Austria |
| City | Vienna |
| Period | 7/04/13 → 12/04/13 |
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Biophysical controls on evapotranspiration and water use efficiency in natural, semi-natural and managed African ecosystems. / Brümmer, C.; Merbold, L.; Archibald, S.; Ardö, J.; Arneth, A.; Veenendaal, E.M.
2013. Paper presented at EGU General Assembly 2013, Vienna, Austria.Research output: Contribution to conference › Conference paper › Academic
TY - CONF
T1 - Biophysical controls on evapotranspiration and water use efficiency in natural, semi-natural and managed African ecosystems
AU - Brümmer, C.
AU - Merbold, L.
AU - Archibald, S.
AU - Ardö, J.
AU - Arneth, A.
AU - Veenendaal, E.M.
N1 - id. EGU2013-8102
PY - 2013
Y1 - 2013
N2 - The effects of climatic factors and vegetation type on evapotranspiration (E) and water use efficiency (WUE) were analyzed using tower-based eddy-covariance (EC) data of eleven African sites (22 site years) located across a continental-scale transect. The seasonal pattern of E was closely linked to growing-season length and rainfall distribution. Although annual precipitation (P) was highly variable among sites (290 to 1650 mm), minimum annual E was not less than 250 mm and reached a maximum of 900 mm where annual P exceeded 1200 mm. Site-specific interannual variability in E could be explained by either changes in total P or variations in solar irradiance. At some sites, a highly positive linear correlation was found between monthly sums of E and net radiation (Rn), whereas a hysteretic relationship at other sites indicated that E lagged behind the typical seasonal progression of Rn. Results of a cross-correlation analysis between daily (24-h) E and Rn revealed that site-specific lag times were between 0 days and up to a few weeks depending on the lag of vapor pressure deficit (D) behind Rn and vegetation type. Physiological parameters (e.g. mean dry-foliage Priestley-Taylor alpha) implied that stomatal limitation to transpiration prevailed. During the rainy season, a strong linear correlation between monthly mean values of gross primary production (GPP) and E resulted in water use efficiency being constant with lower values at grass-dominated sites (~2 to ~3.5 g C kg-1 H2O) than at natural woodland sites and plantations (~4.5 to ~6 g C kg-1 H2O).
AB - The effects of climatic factors and vegetation type on evapotranspiration (E) and water use efficiency (WUE) were analyzed using tower-based eddy-covariance (EC) data of eleven African sites (22 site years) located across a continental-scale transect. The seasonal pattern of E was closely linked to growing-season length and rainfall distribution. Although annual precipitation (P) was highly variable among sites (290 to 1650 mm), minimum annual E was not less than 250 mm and reached a maximum of 900 mm where annual P exceeded 1200 mm. Site-specific interannual variability in E could be explained by either changes in total P or variations in solar irradiance. At some sites, a highly positive linear correlation was found between monthly sums of E and net radiation (Rn), whereas a hysteretic relationship at other sites indicated that E lagged behind the typical seasonal progression of Rn. Results of a cross-correlation analysis between daily (24-h) E and Rn revealed that site-specific lag times were between 0 days and up to a few weeks depending on the lag of vapor pressure deficit (D) behind Rn and vegetation type. Physiological parameters (e.g. mean dry-foliage Priestley-Taylor alpha) implied that stomatal limitation to transpiration prevailed. During the rainy season, a strong linear correlation between monthly mean values of gross primary production (GPP) and E resulted in water use efficiency being constant with lower values at grass-dominated sites (~2 to ~3.5 g C kg-1 H2O) than at natural woodland sites and plantations (~4.5 to ~6 g C kg-1 H2O).
M3 - Conference paper
ER -