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Figure 6.11
Example of an experimental plot in a
Carex
-dominated fen at the
geothermally active research site near the Hengill area in Iceland.
(a)
(b)
0.7
3.0
Fertilized
Control
Fertilized
Control
0.6
2.5
0.5
2.0
0.4
1.5
0.3
1.0
0.2
0.5
0.1
0
0
Cold
Warm
Cold
Warm
N
2
O production
DEA
DEA
Figure 6.12
N
2
O emissions measured (a)
in situ
from wetland soils of N-fertilized and
control plots at both ambient and geothermally elevated temperatures (mean ± SE,
N
= 6) and (b) in wetland soil slurries under controlled conditions in the laboratory.
Green bars represent incubation of soils from warm locations (30 °C), blue bars from
cold locations (15 °C) (mean ± SE,
N
= 8). DEA, denitrification enzyme activity.
emission and DEA increased with N-enrichment but not significantly with
temperature, although emissions were highest under both N-enrichment and
elevated temperature (Fig. 6.12). The N
2
O/N
2
ratios did not differ significantly
between N-amended soils sampled from ambient and warm field sites.
In conclusion, N-enrichment thus clearly stimulated N
2
O production under both
field and laboratory conditions, whereas a rise in temperature alone had only a
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