16
Agnes Hereter and Juan Rafael Sanchez
metamorphic phyllites and schists, and by granodiorites. The relief is very
steep. Climatically and biogeographically Montseny lies at a northern
boundary of the Mediterranean region. At mid-altitudes, where our experimental sites are located, the climate is Mediterranean, but the characteristic
summer drought is attenuated by summer storms. The massif is forested, except in its upper reaches. Altitudinal changes in vegetation are prominent,
with pine forests, evergreen holm oak forests, beech forests, and heathlands
and grasslands dominating in this order at increasing altitudes (Bolos 1983).
Holm oak forests cover about 50% of the natural park.
The Prades mountains are located 100 km WSW of Barcelona. They cover
about 260 kmZ, and the highest altitude is 1201 m a.s.l. The massif is designated as a site of natural interest, a conservation category that conveys a mild
degree of protection. Part of the massif, the Valley of the Poblet Monastery
including the Poblet Forest, benefits from stronger protection as a natural
site of national interest. The Prades mountains are surrounded by lowlands
devoted to dry farming. The cities of Tarragona and Reus, totalling 200 000
people and harbouring major petrochemical industries, lie 30 km to the
south. The climate is typically Mediterranean with a marked summer dry period. There are two major geological units: a Palaeozoic base (metamorphic
and igneous rocks) and a Mesozoic cover (limestone, dolomite, clay and
sandstone) (Poblet and Pujadas 1988). The relief is flat on the Mesozoic top
of the massif and very steep on the Palaeozoic slopes. The vegetation changes
from Aleppo pine forests at low altitudes to holm oak forests and Scots pine
forests (Mestres and Massalles 1988). Extensive shrublands occur, particularly on the driest and thinnest soils.
2.2 Experimental Areas at Montseny
The major experimental area used at Montseny was La Castanya Biological
Station (41
0
46' N, 2
0
21' E), in the central sector of the massif. It was established in 1977 and used mainly for functional studies at the tree, plot and
catchment scales. A second experimental area, Figar6, was established in
1990 in the southwestern sector of Montseny for studying stand dynamics.
The major characteristics of the study sites are summarized in Table 2.1.
2.2.1 Experimental Layout
La Castanya valley lies at the heart of the Palaeozoic core of Montseny. Most
studies at La Castanya Biological Station were conducted in and around a
200-ha catchment (named TMO) drained by the Torrent de la Mina stream,
which flows in a NE direction (Fig. 2.2). On the north-facing slope of the Torrent de la Mina catchment, a small tributary, named TM9, draining a 5.9-ha
Agnes Hereter and Juan Rafael Sanchez
metamorphic phyllites and schists, and by granodiorites. The relief is very
steep. Climatically and biogeographically Montseny lies at a northern
boundary of the Mediterranean region. At mid-altitudes, where our experimental sites are located, the climate is Mediterranean, but the characteristic
summer drought is attenuated by summer storms. The massif is forested, except in its upper reaches. Altitudinal changes in vegetation are prominent,
with pine forests, evergreen holm oak forests, beech forests, and heathlands
and grasslands dominating in this order at increasing altitudes (Bolos 1983).
Holm oak forests cover about 50% of the natural park.
The Prades mountains are located 100 km WSW of Barcelona. They cover
about 260 kmZ, and the highest altitude is 1201 m a.s.l. The massif is designated as a site of natural interest, a conservation category that conveys a mild
degree of protection. Part of the massif, the Valley of the Poblet Monastery
including the Poblet Forest, benefits from stronger protection as a natural
site of national interest. The Prades mountains are surrounded by lowlands
devoted to dry farming. The cities of Tarragona and Reus, totalling 200 000
people and harbouring major petrochemical industries, lie 30 km to the
south. The climate is typically Mediterranean with a marked summer dry period. There are two major geological units: a Palaeozoic base (metamorphic
and igneous rocks) and a Mesozoic cover (limestone, dolomite, clay and
sandstone) (Poblet and Pujadas 1988). The relief is flat on the Mesozoic top
of the massif and very steep on the Palaeozoic slopes. The vegetation changes
from Aleppo pine forests at low altitudes to holm oak forests and Scots pine
forests (Mestres and Massalles 1988). Extensive shrublands occur, particularly on the driest and thinnest soils.
2.2 Experimental Areas at Montseny
The major experimental area used at Montseny was La Castanya Biological
Station (41
0
46' N, 2
0
21' E), in the central sector of the massif. It was established in 1977 and used mainly for functional studies at the tree, plot and
catchment scales. A second experimental area, Figar6, was established in
1990 in the southwestern sector of Montseny for studying stand dynamics.
The major characteristics of the study sites are summarized in Table 2.1.
2.2.1 Experimental Layout
La Castanya valley lies at the heart of the Palaeozoic core of Montseny. Most
studies at La Castanya Biological Station were conducted in and around a
200-ha catchment (named TMO) drained by the Torrent de la Mina stream,
which flows in a NE direction (Fig. 2.2). On the north-facing slope of the Torrent de la Mina catchment, a small tributary, named TM9, draining a 5.9-ha