Geoscience Reference
In-Depth Information
5
Minimum depth of all O horizons of 40 cm.
6
Fibrous remains of cotton-grass sedges (
Eriophorum
spp.), bog moss (
Sphagnum
spp.) and many other
moorland plants.
7
pH less than 4.0.
This soil is widely distributed throughout upland Britain,
where high rainfall and low evaporation lead to water-
logging which depresses decomposition of plant remains.
The lower limit of altitude decreases as one moves
westwards in Britain, and indeed reaches sea level in
western Ireland and parts of Scotland. Because the peat
is not confined to low-lying or basin sites, but covers
undulating and sloping terrain like a 'blanket', Harry
Godwin suggested the name '
blanket bog
'. The term
'Oligotrophic' in the FAO name denotes that the peat is
acid, and both supports and is formed from, plant species
which have low nutritional requirements, e.g. cotton grass,
bog moss, heather (
Calluna vulgaris
), rushes (
Juncus
spp.)
and
Cladonia
lichens. The term
ombrotrophic
(Greek
'cloud-feeding') is frequently used to describe
Sphagnum
Lanka, with virgin tropical monsoon forest above.
Photo: R. T. Smith
N
2
N
2
O
NH
3
Direction of diffusion
N
2
Water
NH
4
+
NO
2
-
NO
3
-
Aerobic soil
NITRIFICATION
Anaerobic soil
MINERALIZATION
ORGANIC
N
NH
4
+
DENITRIFICATION
N
2
N
2
O
NO
3
-
