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| Reth, S; Göckede, M; Falge, E: CO2 efflux from agricultural soils in Eastern Germany - commparison of a closed chamber system with eddy covariance measurements, Theoretical and Applied Climatology, 80, 105-120 (2005) | |
Abstract:
In order to quantify the effects of temperature and soil
water content on soil respiration, during June and July 2002
CO2 soil efflux was measured with a closed chamber (nonsteady
state, flow through) system in the field. The amount
of CO2 emission was highly dependent on the land-use in
the observation area, which consisted of meadow soil and
brownfield. The CO2 emission from the brownfield ranged
from 0.9 to 5.5 mmol CO2 m2 s1, and that for meadow
soil from 1.1 to 12.6 mmol CO2 m2 s1. Soil respiration, as
a function of soil temperature (Tsoil), relative soil water
content (RSWC), soil pH, and the soil carbon=nitrogen
ratio (C=N), was analysed by a modified closed non-linear
regression model. Between 63% and 81% of the variation
of soil CO2 emission could be explained with changes of
Tsoil, RSWC, pH, and C=N for the individual chambers on
the brownfield.
Subsequent analysis involved a comparison of the soil
chamber results with eddy covariance (EC) measurements
of one week, and included a footprint analysis to account
for the influence of the different land use types on the measurements.
For this, EC data (143 measurements after quality
check) were restricted to those originating from the brown-
field area with more than 90% of the flux. For a second
comparison, the net ecosystem exchange (NEE) was calculated
for different parts of the meadow using the SVAT
model PROXEL. Together with the respiration from the
brownfield, a weighted average of model NEE was produced
using the flux contribution determined by the footprint
model. Acceptable agreement (r2¼0.69) was found between
the modelled data and individual EC measurements, except during situations where the performance of the footprint
model was disturbed by internal boundary layer effects.
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