12
Jaume Terradas
milk and meat production. Dehesas are also excellent for hunting. The system is managed by preventing woody plants from invading grasslands
through grazing, disking and hand weeding, with a high labour effort. This
sustainable and ecologically diverse system is endangered by the spread of
cereal-intensive monocultures using large amounts of fertilizers and pesticides.
Dehesas are very interesting ecosystems, but our subject in this book are
the closed-canopy holm oak forests prevalent in eastern Spain. In contrast to
the dehesas, in eastern Spain, including Catalonia, and in most of the Mediterranean regions of France, Italy, and Greece, charcoal and firewood were
the main products obtained from holm oak. As a result, these forests have
been managed as coppices or coppice-with-standards at least since the Neolithic period. At Montseny, cutting intervals were short for charcoal (usually
10-15 years), increasing to 20-25 years if the largest boles were used for timber (Gutierrez 1996). Selection thinning was the most frequently used coppicing method, with about one third of the usable stems harvested at each
cutting (Gutierrez 1996). Clear-cutting or almost clear-cutting was also
sometimes used. Regular and frequent coppicing of holm oak forests was
also the rule in other Mediterranean countries (Ducrey and Boisserie 1992;
Giovannini et al. 1992; Bacillieri et al. 1993). Coppicing has created forests
with high tree densities, and the ensuing intense competition leads to a low
growth rate of individual stems (Chap. 3). Charcoal production, very important in the past, has practically disappeared. Tannin from the bark of young
trees was another major product, but synthetic tannins have superseded such
production in the last 30 years. The main current use is for firewood. In
Catalonia, selection thinning at intervals of (IS) 20-35 years is mostly used,
leading to uneven-aged stands where restocking is almost exclusively based
on stump resprouting (Chaps. 3 and 5). Natural seedling recruitment (usual
in other oak forests) is minimal in Catalan holm oak forests (Espelta et al.
1995; Chap. 7). Multiple use is in fact occurring, but not as a result of planning. For instance, coppicing has been always accompanied by sheep and
goat grazing (cutting holm oak induces sprouting, with an increase in leaf
production that can be used by livestock). Acorns play an important role in
the diet of sheep during the winter: sheep, and sometimes cows, may also
graze on the herbaceous layer of recently-coppiced stands, whereas goats
feed directly on holm oak leaves and young twigs. When deciduous oaks are
present, they are preferred to holm oaks by browsers, due to the higher content of cutin, lignin and tannins and the lower content of proteins in holm
oak. This can give holm oak a competitive advantage over deciduous oaks in
some parts of its distribution range. However, in the experimental areas on
which this book is based, grazing by domestic herbivores is currently not a
major ecological factor.
Jaume Terradas
milk and meat production. Dehesas are also excellent for hunting. The system is managed by preventing woody plants from invading grasslands
through grazing, disking and hand weeding, with a high labour effort. This
sustainable and ecologically diverse system is endangered by the spread of
cereal-intensive monocultures using large amounts of fertilizers and pesticides.
Dehesas are very interesting ecosystems, but our subject in this book are
the closed-canopy holm oak forests prevalent in eastern Spain. In contrast to
the dehesas, in eastern Spain, including Catalonia, and in most of the Mediterranean regions of France, Italy, and Greece, charcoal and firewood were
the main products obtained from holm oak. As a result, these forests have
been managed as coppices or coppice-with-standards at least since the Neolithic period. At Montseny, cutting intervals were short for charcoal (usually
10-15 years), increasing to 20-25 years if the largest boles were used for timber (Gutierrez 1996). Selection thinning was the most frequently used coppicing method, with about one third of the usable stems harvested at each
cutting (Gutierrez 1996). Clear-cutting or almost clear-cutting was also
sometimes used. Regular and frequent coppicing of holm oak forests was
also the rule in other Mediterranean countries (Ducrey and Boisserie 1992;
Giovannini et al. 1992; Bacillieri et al. 1993). Coppicing has created forests
with high tree densities, and the ensuing intense competition leads to a low
growth rate of individual stems (Chap. 3). Charcoal production, very important in the past, has practically disappeared. Tannin from the bark of young
trees was another major product, but synthetic tannins have superseded such
production in the last 30 years. The main current use is for firewood. In
Catalonia, selection thinning at intervals of (IS) 20-35 years is mostly used,
leading to uneven-aged stands where restocking is almost exclusively based
on stump resprouting (Chaps. 3 and 5). Natural seedling recruitment (usual
in other oak forests) is minimal in Catalan holm oak forests (Espelta et al.
1995; Chap. 7). Multiple use is in fact occurring, but not as a result of planning. For instance, coppicing has been always accompanied by sheep and
goat grazing (cutting holm oak induces sprouting, with an increase in leaf
production that can be used by livestock). Acorns play an important role in
the diet of sheep during the winter: sheep, and sometimes cows, may also
graze on the herbaceous layer of recently-coppiced stands, whereas goats
feed directly on holm oak leaves and young twigs. When deciduous oaks are
present, they are preferred to holm oaks by browsers, due to the higher content of cutin, lignin and tannins and the lower content of proteins in holm
oak. This can give holm oak a competitive advantage over deciduous oaks in
some parts of its distribution range. However, in the experimental areas on
which this book is based, grazing by domestic herbivores is currently not a
major ecological factor.