24
Agnes Hereter and Juan Rafael Sanchez
2.3 Experimental Area at Prades
2.3.1 Experimental Layout
The Prades experimental area is located within the Poblet Forest (41 ° 13' N,
0° 55' E) in the Prades mountains (Fig. 2.1). It was established in 1980. Two
major valleys harbour the experimental catchments and plots: the Titllar
valley and the Torners valley (Fig. 2.4). Within the Titllar valley two northfacing, adjacent holm oak forested catchments were gaged in 1981, and have
been continuously monitored for water and nutrient budgets since then.
These catchments (Avic, 51.6 ha, and Teula, 38.5 ha) have been the subject of
many studies on the hydrology and biogeochemistry of holm oak forest. In
the Avic catchment intensive ecophysiological work on holm oak was conducted at two sites in the upper and lower parts of the catchment. The major
characteristics of these study sites are summarized in Table 2.1.
A third catchment (Saucar) was gaged in the upper reaches of the Torners
valley. On the slopes of the Torners valley three major plot-level experiments
have been conducted in holm oak stands. In the east- to southeast-facing
slope, one experiment addressed the effects of an experimental fire and/or
clear-cutting on soil properties, nutrient losses, and stump resprouting. A
second experiment on an adjacent site investigated the effects of irrigation
and/or fertilization of tree growth, primary production, and nutrient cycling.
On the opposite, north-facing slope of Torners a thinning experiment was
conducted to assess tree and stand responses to decreased stem density. A
fourth catchment (Castellfollit) was also monitored in an adjacent valley, but
since it was covered mainly by Scots pine it is not dealt with in this book.
2.3.2 Climate
The climate of the Prades study sites is typically Mediterranean (more so
than at Montseny), with a mean annual precipitation at the nearby Poblet
Monastery of 537 mm (range 360-768 mm, period 1981-1995). The summer
is markedly dry, and there are two precipitation maxima in autumn and
spring (Fig. 2.3). An indication of the annual water deficit can be gained
through the evaporation measured with a Piche evaporimeter at Poblet Monastery, which averages 1043 mm year-I. The mean annual air temperature is
13.6°C at Riudabella (485 m a.s.l., and 3.5 km to the north from the Avic
catchment) and 10°C at Prades (950 m a.s.l.).
2.3.3 Lithology and Relief
The bedrock at the study sites is mostly Palaeozoic phyllite with small
amounts of metamorphic sandstones with microconglomerates.· Phyllite and
schists dominate at the Avic and Teula catchments, with the frequency ofmetamorphic sandstones increasing from Titllar towards Torners. Relief is very
Agnes Hereter and Juan Rafael Sanchez
2.3 Experimental Area at Prades
2.3.1 Experimental Layout
The Prades experimental area is located within the Poblet Forest (41 ° 13' N,
0° 55' E) in the Prades mountains (Fig. 2.1). It was established in 1980. Two
major valleys harbour the experimental catchments and plots: the Titllar
valley and the Torners valley (Fig. 2.4). Within the Titllar valley two northfacing, adjacent holm oak forested catchments were gaged in 1981, and have
been continuously monitored for water and nutrient budgets since then.
These catchments (Avic, 51.6 ha, and Teula, 38.5 ha) have been the subject of
many studies on the hydrology and biogeochemistry of holm oak forest. In
the Avic catchment intensive ecophysiological work on holm oak was conducted at two sites in the upper and lower parts of the catchment. The major
characteristics of these study sites are summarized in Table 2.1.
A third catchment (Saucar) was gaged in the upper reaches of the Torners
valley. On the slopes of the Torners valley three major plot-level experiments
have been conducted in holm oak stands. In the east- to southeast-facing
slope, one experiment addressed the effects of an experimental fire and/or
clear-cutting on soil properties, nutrient losses, and stump resprouting. A
second experiment on an adjacent site investigated the effects of irrigation
and/or fertilization of tree growth, primary production, and nutrient cycling.
On the opposite, north-facing slope of Torners a thinning experiment was
conducted to assess tree and stand responses to decreased stem density. A
fourth catchment (Castellfollit) was also monitored in an adjacent valley, but
since it was covered mainly by Scots pine it is not dealt with in this book.
2.3.2 Climate
The climate of the Prades study sites is typically Mediterranean (more so
than at Montseny), with a mean annual precipitation at the nearby Poblet
Monastery of 537 mm (range 360-768 mm, period 1981-1995). The summer
is markedly dry, and there are two precipitation maxima in autumn and
spring (Fig. 2.3). An indication of the annual water deficit can be gained
through the evaporation measured with a Piche evaporimeter at Poblet Monastery, which averages 1043 mm year-I. The mean annual air temperature is
13.6°C at Riudabella (485 m a.s.l., and 3.5 km to the north from the Avic
catchment) and 10°C at Prades (950 m a.s.l.).
2.3.3 Lithology and Relief
The bedrock at the study sites is mostly Palaeozoic phyllite with small
amounts of metamorphic sandstones with microconglomerates.· Phyllite and
schists dominate at the Avic and Teula catchments, with the frequency ofmetamorphic sandstones increasing from Titllar towards Torners. Relief is very