26
Agnes Hereter and Juan Rafael Sanchez
2.3.4 Soils
The soils in the Prades experimental area are Inceptisols and Entisols. In the
experimental catchments, the soils are Xerochrepts with subgroups differing
between topographic positions: lithic on the upper slope of the catchments
and typic on the valley bottom. Major soil characteristics of the study sites
are shown in Table 2.2.
Soil depth usually ranges between 30 and 80 cm, but reaches 150 cm at
valley bottom sites. There is a high content of coarse rock fragments, and the
dominant soil texture is clay loam. Soil pH is much higher than at Montseny,
particularly than at La Castanya. At Prades, soil pH on the lower slope is
higher than on the upper slope. The cation exchange complex is saturated,
Ca 2 + being the predominant exchangeable cation. Small quantities of CaC03
«0.3%) are detectable in the soil through gas chromatography after acidifying soil samples.
2.3.5 Vegetation
The vegetation at the Avic and Teula catchments is a closed-canopy holm oak
forest. The upper parts of the catchments have a lower diversity of plant species and the vegetation can be included in the Asplenio-Quercetum association. In the lower parts, with a higher plant diversity and higher presence of
termophilic species, it can be included in the Viburno-Quercetum association
(Folch and Velasco 1978). The dominant species at all altitudes is holm oak,
with Arbutus unedo and Phillyrea latifolia subsp. media as major companion
species in the understory and, occasionally, also in the overstory (Lled6 et al.
1992). At Torners, the same overall composition applies, with holm oak being
even more dominant there. Overall, the overstory of holm oak forests in the
Prades experimental area is less monospecific than at Montseny. At Prades,
besides the evergreens Arbutus unedo and Phillyrea latifolia, Pinus nigra is
sometimes present, and there is a minor but significant deciduous component made up of Quercus cerrioides (a marcescent to deciduous oak), Acer
monspessulanum, and Sorbus torminalis.
The forest history at Prades is in broad terms similar to that described for
Montseny. However, the Poblet Forest where our Prades experimental sites
are located belonged for centuries to the Poblet Monastery. This provided
some degree of protection, because though the forest was harvested, the
monks saw it as a source of income and strove to use it wisely. There are frequent records of the struggle between villagers pressing for increasing the
harvesting and the monks trying to limit it. The intensity of forest exploitation for firewood and charcoal generally increased until the eighteenth century. In more recent times, the Poblet Forest, and more specifically the Avic
and Teula catchments, was heavily coppiced for charcoal after the Spanish
civil war (1936-1939). The forest was almost totally felled during the 15 years
that followed this period. The present forest is made of the stump resprouts
Agnes Hereter and Juan Rafael Sanchez
2.3.4 Soils
The soils in the Prades experimental area are Inceptisols and Entisols. In the
experimental catchments, the soils are Xerochrepts with subgroups differing
between topographic positions: lithic on the upper slope of the catchments
and typic on the valley bottom. Major soil characteristics of the study sites
are shown in Table 2.2.
Soil depth usually ranges between 30 and 80 cm, but reaches 150 cm at
valley bottom sites. There is a high content of coarse rock fragments, and the
dominant soil texture is clay loam. Soil pH is much higher than at Montseny,
particularly than at La Castanya. At Prades, soil pH on the lower slope is
higher than on the upper slope. The cation exchange complex is saturated,
Ca 2 + being the predominant exchangeable cation. Small quantities of CaC03
«0.3%) are detectable in the soil through gas chromatography after acidifying soil samples.
2.3.5 Vegetation
The vegetation at the Avic and Teula catchments is a closed-canopy holm oak
forest. The upper parts of the catchments have a lower diversity of plant species and the vegetation can be included in the Asplenio-Quercetum association. In the lower parts, with a higher plant diversity and higher presence of
termophilic species, it can be included in the Viburno-Quercetum association
(Folch and Velasco 1978). The dominant species at all altitudes is holm oak,
with Arbutus unedo and Phillyrea latifolia subsp. media as major companion
species in the understory and, occasionally, also in the overstory (Lled6 et al.
1992). At Torners, the same overall composition applies, with holm oak being
even more dominant there. Overall, the overstory of holm oak forests in the
Prades experimental area is less monospecific than at Montseny. At Prades,
besides the evergreens Arbutus unedo and Phillyrea latifolia, Pinus nigra is
sometimes present, and there is a minor but significant deciduous component made up of Quercus cerrioides (a marcescent to deciduous oak), Acer
monspessulanum, and Sorbus torminalis.
The forest history at Prades is in broad terms similar to that described for
Montseny. However, the Poblet Forest where our Prades experimental sites
are located belonged for centuries to the Poblet Monastery. This provided
some degree of protection, because though the forest was harvested, the
monks saw it as a source of income and strove to use it wisely. There are frequent records of the struggle between villagers pressing for increasing the
harvesting and the monks trying to limit it. The intensity of forest exploitation for firewood and charcoal generally increased until the eighteenth century. In more recent times, the Poblet Forest, and more specifically the Avic
and Teula catchments, was heavily coppiced for charcoal after the Spanish
civil war (1936-1939). The forest was almost totally felled during the 15 years
that followed this period. The present forest is made of the stump resprouts