Environmental Engineering Reference
In-Depth Information
diminished the heterotrophic respiration as well. With an annual soil CO
2
efflux of
17.4 Mg C ha
−
1
y
−
1
(year 2003; Bahn et al.
2008
) this site resulted to have among
the highest level of CO
2
rates among a series of thirteen European grasslands and
meadow ecosystems (Bahn et al.
2008
). The high 2003 CO
2
emissions were due to
the high average annual soil temperature being 9.7 °C at 5 cm depth. In 2004 there
was a much lower efflux (11.0 Mg C ha
−
1
y
−
1
) and a lower soil temperature (6.8 °C).
ured on twenty collars randomly positioned around the eddy flux tower. The measure-
ment techniques and fluxes calculation are the same as those reported above for the
meadow site. Annual totals of soil respiration were evaluated by applying the above
reported model (Eq.
8.1
). The total soil respiration in a given year was calculated by
summing up the fluxes estimated by the model from continuous temperature data.
The temperature dependency of soil respiration was even higher than in
the meadow, being the variance accounted for by the model 0.83 (Fig.
8.6
b).
Fig. 8.6
Temperature dependency of soil CO
2
efflux for two sites located in Trentino region
according to the model described in Eq.
8.1
. The meadow (
a
) has higher values both of respira-
tion at 10 °C (R
10
) and activation energy (E
0
) compared to the vineyard (
b
). See text for further
details
