Environmental Engineering Reference
In-Depth Information
precedent, many of the arid and semi-arid lands are
without clearly defi ned owners or explicitly owned by
the government, but lacking clear management and
supervision. Both situations lead to over-exploitation
and discourage investment of time, energy and fi nan-
cial capital in long-term projects of conservation and
restoration. The result is overuse, soil loss and eventu-
ally decline to bare rock and abandonment. Restora-
tion efforts can be facilitated if tenure can be clarifi ed
by agreement or legislation. Satellite photos and
mapping can make tenure allocation easier (William-
son 2000 ).
oriented group studies like those proposed here are
among the best method for developing these skills.
These types of applied transdisciplinary studies do
not fi t in comfortably with the current academic
environment (Bainbridge 1985, 2007b; Janssen &
Goldsworthy 1996 ).
10.3.1 Improving understanding of the
socio-economic and ecological setting
The primary challenge of restoration is to reverse the
process of desertifi cation, to capture and retain more
water and to begin re-establishing plant communities
and
ecosystem health
and complexity. Many tech-
niques can be used to improve water capture, storage
and infi ltration, depending on soil conditions, budget
and equipment availability. These include decompact-
ing or scarifying the surface to break up crusts and
increase water capture, laying out rock lines (Figure
10.2) or grids to slow surface fl ow and increase ab-
sorption, spreading brush or vegetation and creating
swales, microcatchments or berms to capture rain
(Tongway & Ludwig 1996 ; Lancaster 2008 ; Chapter
4). Soil amendments, planting and restoration of soil
microorganisms can also increase water capture and
infi ltration. Establishment and succession can be very
slow on undisturbed arid and semi-arid lands, and any
additional damage due to mismanagement makes
plant establishment even more diffi cult (Bainbridge
2007a). Techniques to capture and store water are
essential, but just a start.
In the drylands, more than anywhere else, restora-
tion planning must be based on understanding, inter-
vention must be timely and restoration workers must
be persistent. The planning effort should include con-
sideration of ecosystem structure, function and use.
Traditionally planning has focused on
ecosystem
structure
, 'How many plants should be planted per
acre or hectare? What canopy cover should be sought?'
but repairing
ecosystem function
, ' How does water
fl ow through the site? What is the soil health?' is often
more important (Aronson
et al
. 2002 ; Bainbridge
2007a). Restoring function can speed
recovery
and
make long-term success more likely (Allen 1988;
Whisenant 1999). Attempting to return a plot of land
to the historic plant community by seeding or con-
tainer planting without restoring the soil and water
functions that supported that community has led to
many costly failures. Restoration of protected areas
10.2.3
Ecological factors
In arid and semi-arid lands, water is the major limiting
factor for plant establishment and growth. In degraded
or desertifi ed areas, this defi cit becomes even more
critical. Even if viable seeds are still present in the soil
seed bank
, they cannot germinate or grow without
water; and changes in surface soils, microclimate and
removal of vegetation and litter increase
runoff
, limit
water retention and slow water movement into the
soil (infi ltration). As soil water is restricted by these
changes, the decline in biomass intensifi es grazing
pressure on the few remaining plants in a downward
spiral that may end with barren rock.
10.3 THE RESTORATION RESEARCH
CHALLENGE
Restoring degraded ecosystems in arid and semi-arid
lands requires a clear understanding of the complex
interplay of environmental and social factors and the
increasing impact of
climate change
(Reynolds
et al
.
2007). Basic research is also needed to better under-
stand less disturbed
reference ecosystems
and to
identify effects from climate change. The unpredicta-
bility of climate in most desert and semi-arid regions,
and the extreme conditions at the soil surface make
restoration challenging even when adequate fi nancial
resources are available. Restoration research is needed
to help clarify the best strategies for each site and
situation.
Renewed funding for fi eldwork and applied research
is urgently needed. Training for both participating in
and managing
transdisciplinary
fi eld studies is
extremely important, yet rarely offered. Problem-
