Very high CO2 exchange fluxes at the peak of the rainy season in a West African grazed semi-arid savanna ecosystem
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
Standard
Very high CO2 exchange fluxes at the peak of the rainy season in a West African grazed semi-arid savanna ecosystem. / Tagesson, Håkan Torbern; Ardoe, Jonas; Guiro, Idrissa; Cropley, Ford; Mbow, Cheikh; Horion, Stéphanie Marie Anne F; Ehammer, Andrea; Mougin, Eric; Delon, Claire; Galy-Lacaux, Corinne; Fensholt, Rasmus.
I: Geografisk Tidsskrift/Danish Journal of Geography, Bind 116, Nr. 2, 2016, s. 93-109.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
Harvard
APA
Vancouver
Author
Bibtex
}
RIS
TY - JOUR
T1 - Very high CO2 exchange fluxes at the peak of the rainy season in a West African grazed semi-arid savanna ecosystem
AU - Tagesson, Håkan Torbern
AU - Ardoe, Jonas
AU - Guiro, Idrissa
AU - Cropley, Ford
AU - Mbow, Cheikh
AU - Horion, Stéphanie Marie Anne F
AU - Ehammer, Andrea
AU - Mougin, Eric
AU - Delon, Claire
AU - Galy-Lacaux, Corinne
AU - Fensholt, Rasmus
PY - 2016
Y1 - 2016
N2 - Africa is a sink of carbon, but there are large gaps in our knowledge regarding the CO2 exchangefluxes for many African ecosystems. Here, we analyse multi-annual eddy covariance data of CO2exchange fluxes for a grazed Sahelian semi-arid savanna ecosystem in Senegal, West Africa. The aimof the study is to investigate the high CO2 exchange fluxes measured at the peak of the rainy seasonat the Dahra field site: gross primary productivity and ecosystem respiration peaked at values upto −48 μmol CO2 m−2 s−1 and 20 μmol CO2 m−2 s−1, respectively. Possible explanations for such highfluxes include a combination of moderately dense herbaceous C4 ground vegetation, high soilnutrient availability and a grazing pressure increasing the fluxes. Even though the peak net CO2uptake was high, the annual budget of −229 ± 7 ± 49 g C m−2 y−1 (±random errors ± systematicerrors) is comparable to that of other semi-arid savanna sites due the short length of the rainyseason. An inter-comparison between the open-path and a closed-path infrared sensor indicated nosystematic errors related to the instrumentation. An uncertainty analysis of long-term NEE budgetsindicated that corrections for air density fluctuations were the largest error source (11.3% out of24.3% uncertainty). Soil organic carbon data indicated a substantial increase in the soil organiccarbon pool for the uppermost .20 m. These findings have large implications for the perception ofthe carbon sink/source of Sahelian ecosystems and its response to climate change.
AB - Africa is a sink of carbon, but there are large gaps in our knowledge regarding the CO2 exchangefluxes for many African ecosystems. Here, we analyse multi-annual eddy covariance data of CO2exchange fluxes for a grazed Sahelian semi-arid savanna ecosystem in Senegal, West Africa. The aimof the study is to investigate the high CO2 exchange fluxes measured at the peak of the rainy seasonat the Dahra field site: gross primary productivity and ecosystem respiration peaked at values upto −48 μmol CO2 m−2 s−1 and 20 μmol CO2 m−2 s−1, respectively. Possible explanations for such highfluxes include a combination of moderately dense herbaceous C4 ground vegetation, high soilnutrient availability and a grazing pressure increasing the fluxes. Even though the peak net CO2uptake was high, the annual budget of −229 ± 7 ± 49 g C m−2 y−1 (±random errors ± systematicerrors) is comparable to that of other semi-arid savanna sites due the short length of the rainyseason. An inter-comparison between the open-path and a closed-path infrared sensor indicated nosystematic errors related to the instrumentation. An uncertainty analysis of long-term NEE budgetsindicated that corrections for air density fluctuations were the largest error source (11.3% out of24.3% uncertainty). Soil organic carbon data indicated a substantial increase in the soil organiccarbon pool for the uppermost .20 m. These findings have large implications for the perception ofthe carbon sink/source of Sahelian ecosystems and its response to climate change.
KW - Net ecosystem exchange
KW - Sahel
KW - gross primary productivity
KW - dryland
KW - savanna
KW - ecosystem respiration
U2 - 10.1080/00167223.2016.1178072
DO - 10.1080/00167223.2016.1178072
M3 - Journal article
VL - 116
SP - 93
EP - 109
JO - Geografisk Tidsskrift
JF - Geografisk Tidsskrift
SN - 0016-7223
IS - 2
ER -
ID: 168460499