Geoscience Reference
In-Depth Information
In the mountains of Europe and also on the plains of high latitudes,
Podzols are seen in zones corresponding to a vegetation that provides an
acidifying litter, be it a dense moor with ericaceous plants (
Rhododendron
ferrugineum
,
Calluna vulgaris
,
Vaccinium myrtillus
…) or a combination of
coniferous woods + dense ericaceous undergrowth.
In the Far North, Podzols correspond to coniferous forest (taiga).
In tropical environment, true Podzols seem to be independent of the
vegetation (Bravard 1988; Dosso 1991). But the time periods are long;
changes in vegetation could have taken place and the Podzols might not
be in equilibrium with the present plant cover (Schwartz 1988a, b). In
Amazonia, they are linked to sclerophyllous (evergreen with leathery,
shiny leaves) species (Dubroeucq and Volkoff 1998).
Role of vegetation
Podzolization takes place if the soil is traversed from the top downward
by large volumes of water (
P
-
PET
> 0). When rainfall diminishes, it is
necessary that the temperatures be very low so that evapotranspiration
stays limited. This is the case in Podzols of high latitudes (Fig. 11.5).
Role of climate
Mean annual temperature
Amazonia
30°
Climates unfavourable
for Podzols
Montane rain
forest (Mexico)
with P
20°
Reunion
5
>!
Pilat
(French Massif Central)
10°
Cascade Range
(USA)
Belgian Campine, Galicia
Norway
Chamonix France
(
)
0°
1 m
3 m
P (Average annual rainfall)
2 m
Alaska
Fig. 11.5
Ecology of Podzols. The dots represent the climates corresponding to Podzols
studied and described in the literature.
Under a hot climate characterized by high PET, podzolization is
possible when annual rainfall is very high.
In their natural areas, Podzols are mostly seen on mounds where the
processes of depletion are the strongest. Depressions, saturated with
water, are often occupied by bogs. This is true of Scotland as well as of
Role of topography
