Animals in Agroecosystems - Agroecology: The Ecology of Sustainable Food Systems - page 277

FIGURE 19.7 A simple silvopastoral type of agroforestry system in Puerto Viejo, Costa Rica. The leguminous tree Glyricidia
sepium , used as a living fence, is pruned three to four times per year, and the cattle eat the protein-rich prunings as a complement
to their diet of pasture grasses.
SPAIN'S DEHESA SYSTEM
In mountainous regions of southern Europe, especially in the region of Andalucia, Spain, there exists a traditional
agrosilvopastoral system that integrates livestock, crops, native herbaceous vegetation, and oak forest. Known in
Spain as Dehesa , this integrated system shows the level of complexity and stability that can be achieved by combining
careful management of domestic grazing animals and limited crop agriculture in the context of the natural landscape
(Sevilla Guzman, 1999).
The term “Dehesa” was originally used to refer to parcels of land that were located at the margin of a community's
common grazing areas, meant to be used by specific community members for the pasturing and resting of the animals
used for meeting the farm labor needs of the community. Today, the term describes the management system practiced
on the forested lands surrounding communities, which were Dehesa in the older sense. These areas are vegetated by
an open oak forest of several Quercus species, with an herbaceous understory that germinates with the first rains of
the Mediterranean fall, grows through the winter into spring, and is dry during the rainless summer.
The basis of the Dehesa system is rotational and mixed grazing by the traditional race of Iberian pig (Figure 19.8),
sheep, and occasional horses in the open oak forest. In addition, the people of the community gather firewood and
some cork from the forest, as well as a vast number of native plant species for use as food, medicine, and spices.
In open areas with better soils they grow small plots of forage grasses or legumes. More recently, cattle have been
added to the mix of grazers (Figure 19.4), and native wildlife species are hunted for sport.
The key aspect of the Dehesa is the maintenance of the oak forest ecosystem. This is only possible with the
rational and careful integration of the animal component. Sheep, cattle, and horses graze the natural herbaceous
cover during the winter and spring, after which time they are either sold, moved to lowland areas with better pasture,
or kept in limited numbers on stored forage. The Iberian pig brood-stock and the current year's offspring are kept
in large pens under oaks where they are able to move freely, and are fed grain from the small production areas. In
the late summer when the acorns begin to fall from the trees, the young pigs are released from the pens and allowed
to range freely and feed on the acorns. In a period of less than three months, the pigs gain more than 50% of their