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| Titel |
Spatial variability of heterotrophic and autotrophic soil respiration in a winter wheat stand |
| VerfasserIn |
N. Prolingheuer, B. Scharnagl, A. Graf, H. Vereecken, M. Herbst |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035358
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| Zusammenfassung |
| Soil respiration - the exchange of carbon dioxide from the soil to the adjacent atmospherical
layer - is known to be highly variable in both, space and time. The sources of these carbon
losses are of heterotrophic and autotrophic nature caused by microbial decomposition of
organic matter and respiration from plant roots, respectively. Focus of this study was to
quantify the contribution of each component to the total spatial variability of soil
respiration.
From April to August 2009 closed chamber systems were used to measure soil respiration
weekly at 61 locations in a 50 Ã 50 m plot in a winter wheat stand in Jülich, Germany. Each
sampling location consisted of a short soil collar (10 cm length) to measure total soil
respiration R and a long soil collar (50 cm length) to exclude roots and to measure only
heterotrophic respiration Rh. Additionally, soil temperature T and water content θ in 6 cm
depth were measured simultaneously.
Heterotrophic respiration was almost constant during the study (Rh = 2.12 g C m-2 d-1)
whereas autotrophic respiration was highest in April and decreased down to zero in the mid
of July (Ra = 1.54 g C m-2 d-1). During the study the autotrophic part contributes up to a
maximum of 60 % to the total soil CO2 efflux. Measurements showed that spatial variations
of total soil respiration originate mainly from spatial variations of the heterotrophic part.
When the heterotrophic and the autotrophic efflux was nearly similar during the study spatial
variations of the autotrophic part were two to three times higher than spatial variations of the
heterotrophic part. However, the autotrophic contribution to the total variations of soil
respiration was only 20 %. The dominance of the heterotrophic component was also
found concerning the spatial dependence of total soil respiration. Variogram analysis
revealed only moderate spatial dependence for total soil respiration as well as for its
heterotrophic and autotrophic components. However, the average correlation length of
the heterotrophic part (a = 29 m) was similar to the range of total soil respiration
whereas the corelation length of the autotrophic part was slightly shorter (a = 22 m). |
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