||Carbon dioxide fluxes from a degraded woodland in West Africa and their responses to main environmental factors
AGO Expedit Evariste ,
Serça Dominique ,
AGBOSSOU KOSSI EULOGE ,
GALLE Sylvie ,
AUBINET Marc ,
||Carbon Balance and Management - a SpringerOpen journa
||Background: In West Africa, natural ecosystems such as woodlands are the main source for energy, building poles
and livestock fodder. They probably behave like net carbon sinks, but there are only few studies focusing on their
carbon exchange with the atmosphere. Here, we have analyzed CO2 fluxes measured for 17 months by an eddycovariance
system over a degraded woodland in northern Benin. Specially, temporal evolution of the fluxes and their
relationships with the main environmental factors were investigated between the seasons.
Results: This study shows a clear response of CO2 absorption to photosynthetic photon flux density (Qp), but it varies
according to the seasons. After a significant and long dry period, the ecosystem respiration (R) has increased immediately
to the first significant rains. No clear dependency of ecosystem respiration on temperature has been observed.
The degraded woodlands are probably the “carbon neutral” at the annual scale. The net ecosystem exchange
(NEE) was negative during wet season and positive during dry season, and its annual accumulation was equal to
+29 ± 16 g C m−2. The ecosystem appears to be more efficient in the morning and during the wet season than in the
afternoon and during the dry season.
Conclusions: This study shows diurnal and seasonal contrasted variations in the CO2 fluxes in relation to the alternation
between dry and wet seasons. The Nangatchori site is close to the equilibrium state according to its carbon
exchanges with the atmosphere. The length of the observation period was too short to justify the hypothesis about
the “carbon neutrality” of the degraded woodlands at the annual scale in West Africa. Besides, the annual net ecosystem
exchange depends on the intensity of disturbances due to the site management system. Further research works
are needed to define a woodland management policy that might keep these ecosystems as carbon sinks.
||Eddy-covariance, Woodland, Sudanian climate, Net ecosystem exchange, Annual NEE, Benin, West Africa
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