Environmental Engineering Reference
In-Depth Information
these activities cease, susceptibility to disturbances, especially i re, can be
increased. Fire in turn can have a negative ef ect on biodiversity (Faraco
et al., 1993). Landscape homogenization can also result from the aban-
donment of agricultural/pastoral land (Alés et al., 1992). Without human
management diverse plant communities in the Mediterranean basin, for
example, become overgrown, and displaced by relatively few, shrubby
unproductive species. Livestock may play a positive role in inl uencing the
system.
Bokdam and Gleichman (2000) have suggested that abandonment is
a major threat to traditional pastoral landscapes and their wildlife in
Europe. They report that increased labour costs have undermined tradi-
tional herding systems, which are being replaced by free-ranging grazing
systems leading to a decline in species-rich open heathland. The manage-
ment of Mediterranean woodland has become an important issue in many
areas because of the abandonment of large areas that were previously
exploited by grazing. In many cases impenetrable thickets have developed
with continuous accumulation of fuel leading to catastrophic wildi res.
Valderrábano and Torrano (2000) evaluate goats as a potential manage-
ment tool for controlling encroachment of
Genista scorpius
in black pine
stands in the Spanish Pyrenees. They report that as a consequence of goat
browsing and thinning, dense woodland was opened up and desirable tree
growth and development was stimulated.
In traditional land husbandry, maintenance of biodiversity and eco-
nomic outputs are closely intertwined. For example, the relationship
between habitat characteristics, weather and spatial variation in animal
behaviour was investigated by De Miguel et al.
(1997). They suggest that
shrub areas provide shelter and represent an important browse resource
during winter and that this leads to the occurrence of a diversii ed land-
scape with dif erent successional stages (from pastures to clear and dense
woodlands) that occur in close proximity, which in turn leads to high
levels of l ora and fauna.
Clearly there is evidence to suggest that biodiversity can coexist in land-
scapes of economic importance but can land managers from around the
world actually use biodiversity to support the productive process? This is
the subject of the next section, which considers how land managers may
conserve biodiversity because it supports the productivity, stability and
resilience of the ecosystems they manage.
Landscape management and ecosystem properties
Maintenance of biodiversity may be coincident with management goals
such as improved agricultural productivity under highly variable environ-
mental and socioeconomic conditions. For example, pastoralists in Africa
