Experimental Areas of Prades and Montseny
19
allover the holm oak forest area of the Torrent de la Mina catchment for deriving unbiased forest surveys of the catchment and for monitoring tree
growth. The same year, 18 154-m 2 closed-canopy plots (12 of which belonged
to the previous network) were laid out at different altitudes and slope aspects
within the Torrent de la Mina catchment for production and nutrient cycling
studies (Fig. 2.2).
In the Figar6 experimental area a network of plots varying in aspect, slope
and altitude were used for studies on stand dynamics. Sixty-eight 314-m 2
plots were established in 1990. Nevertheless, in the present book we will deal
mostly with results obtained in those plots where the canopy is dominated by
holm oak.
2.2.2 Climate
At La Castanya the climate is subhumid meso-Mediterranean. Annual precipitation is relatively high, averaging 879 mm at the outlet of the TM9
catchment (annual range 627-1178 mm, period 1983-1995). Summer drought
is present, though attenuated by the relatively high June rainfall and by frequent storms in August and September (Fig. 2.3). As in all our experimental
areas, there is a large interannual variability both in the annual amount and
the monthly distribution of precipitation. Snowfall accounts on average for
only 3% of annual precipitation at the lower altitudes. Snowpacks are sporadical and short-lived in the holm oak forest area, but they persist longer at
altitudes above 1200 m a.s.l. The mean annual air temperature probably varies strongly with altitude, aspect and physiographic position: for the holm
oak forest in the Torrent de la Mina catchment it is estimated to range from
ca. 9°C on the north-facing slope at 1000 m a.s.l. to ca. 13 °C on the lower
reaches of the east-facing slope. At Figar6 the climate is drier than at La
Castanya, the mean annual precipitation being 625 mm (range 423-876 mm,
period 1977-1991). Climate at Figar6 ranges from meso-Mediterranean in
the upper slopes to thermo-Mediterranean in the lower, south-facing slopes.
Topographic variations in mean annual air temperature are likely to vary
strongly also here. At La Garriga, at 250 m a.s.l. and 4 km to the south of the
Figar6 area, the mean annual temperature is 15°C, meaning that for our forest plots in the Figar6 area it must lie around 12-14 °C.
2.2.3 Lithology and Relief
The bedrock at La Castanya is a metamorphic phyllite, with quartz, chlorite,
albite, and muscovite as major minerals. The Torrent de la Mina catchment
has two slopes of contrasting aspect (north- and east-facing, respectively),
both being very steep (mean 34°). The relief of the sideslopes of the catchment is very rugged, with rock outcrops and screes breaking the forest canopy. The relief of the highest part of the catchment is more moderate. The
19
allover the holm oak forest area of the Torrent de la Mina catchment for deriving unbiased forest surveys of the catchment and for monitoring tree
growth. The same year, 18 154-m 2 closed-canopy plots (12 of which belonged
to the previous network) were laid out at different altitudes and slope aspects
within the Torrent de la Mina catchment for production and nutrient cycling
studies (Fig. 2.2).
In the Figar6 experimental area a network of plots varying in aspect, slope
and altitude were used for studies on stand dynamics. Sixty-eight 314-m 2
plots were established in 1990. Nevertheless, in the present book we will deal
mostly with results obtained in those plots where the canopy is dominated by
holm oak.
2.2.2 Climate
At La Castanya the climate is subhumid meso-Mediterranean. Annual precipitation is relatively high, averaging 879 mm at the outlet of the TM9
catchment (annual range 627-1178 mm, period 1983-1995). Summer drought
is present, though attenuated by the relatively high June rainfall and by frequent storms in August and September (Fig. 2.3). As in all our experimental
areas, there is a large interannual variability both in the annual amount and
the monthly distribution of precipitation. Snowfall accounts on average for
only 3% of annual precipitation at the lower altitudes. Snowpacks are sporadical and short-lived in the holm oak forest area, but they persist longer at
altitudes above 1200 m a.s.l. The mean annual air temperature probably varies strongly with altitude, aspect and physiographic position: for the holm
oak forest in the Torrent de la Mina catchment it is estimated to range from
ca. 9°C on the north-facing slope at 1000 m a.s.l. to ca. 13 °C on the lower
reaches of the east-facing slope. At Figar6 the climate is drier than at La
Castanya, the mean annual precipitation being 625 mm (range 423-876 mm,
period 1977-1991). Climate at Figar6 ranges from meso-Mediterranean in
the upper slopes to thermo-Mediterranean in the lower, south-facing slopes.
Topographic variations in mean annual air temperature are likely to vary
strongly also here. At La Garriga, at 250 m a.s.l. and 4 km to the south of the
Figar6 area, the mean annual temperature is 15°C, meaning that for our forest plots in the Figar6 area it must lie around 12-14 °C.
2.2.3 Lithology and Relief
The bedrock at La Castanya is a metamorphic phyllite, with quartz, chlorite,
albite, and muscovite as major minerals. The Torrent de la Mina catchment
has two slopes of contrasting aspect (north- and east-facing, respectively),
both being very steep (mean 34°). The relief of the sideslopes of the catchment is very rugged, with rock outcrops and screes breaking the forest canopy. The relief of the highest part of the catchment is more moderate. The