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| Titel |
Spatial and temporal variation of CO2 efflux along a disturbance gradient in a miombo woodland in Western Zambia |
| VerfasserIn |
L. Merbold, W. Ziegler, M. M. Mukelabai, W. L. Kutsch |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 1 ; Nr. 8, no. 1 (2011-01-21), S.147-164 |
| Datensatznummer |
250005351
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| Publikation (Nr.) |
 copernicus.org/bg-8-147-2011.pdf |
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| Zusammenfassung |
Carbon dioxide efflux from the soil surface was measured over a period of
several weeks within a heterogeneous Brachystegia spp. dominated
miombo woodland in Western Zambia.
The objectives were to examine spatial and temporal variation of soil
respiration along a disturbance gradient from a protected forest reserve to
a cut, burned, and grazed area outside, and to relate the flux to various
abiotic and biotic drivers. The highest daily mean fluxes (around 12 μmol CO2 m−2 s−1) were measured in the protected forest in
the wet season and lowest daily mean fluxes (around 1 μmol CO2 m−2 s−1) in the most disturbed area during the dry season. Diurnal
variation of soil respiration was closely correlated with soil temperature.
The combination of soil water content and soil temperature was found to be
the main driving factor at seasonal time scale. There was a 75% decrease
in soil CO2 efflux during the dry season and a 20% difference in
peak soil respiratory flux measured in 2008 and 2009. Spatial variation of
CO2 efflux was positively related to total soil carbon content in the
undisturbed area but not at the disturbed site. Coefficients of variation of
efflux rates between plots decreased towards the core zone of the protected
forest reserve. Normalized soil respiration values did not vary
significantly along the disturbance gradient. Spatial variation of
respiration did not show a clear distinction between the disturbed and
undisturbed sites and could not be explained by variables such as leaf area
index. In contrast, within plot variability of soil respiration was
explained by soil organic carbon content.
Three different approaches to calculate total ecosystem respiration
(Reco) from eddy covariance measurements were compared to two bottom-up
estimates of Reco obtained from chambers measurements of soil- and leaf
respiration which differed in the consideration of spatial heterogeneity.
The consideration of spatial variability resulted only in small changes of
Reco when compared to simple averaging. Total ecosystem respiration at
the plot scale, obtained by eddy covariance differed by up to 25% in
relation to values calculated from the soil- and leaf chamber efflux
measurements but without showing a clear trend. |
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