Geoscience Reference
In-Depth Information
1989
; Williams et al.,
1995
; Darkoh,
1999
; Williams,
2002b
.)
Causal factor
Consequences
Direct land use
Physical processes affected
Over-cultivation
(shorter fallows; mechanised
farming)
Decline in soil structure and soil permeability; depletion of
soil nutrients and soil organic matter; increased
susceptibility to erosion; compaction of soil; sand dune
mobilisation
Overgrazing
Loss of biodiversity and biomass; increased wind and water
erosion; soil compaction from trampling; increased
run-off; sand dune mobilisation
Mismanagement of irrigated
lands
Waterlogging and salinization of soil; lower crop yields;
possible sedimentation of water reservoirs
Deforestation
(burning to clear land; fuel
and fodder collection)
Promotes artificial establishment of savanna vegetation;
loss of soil-stabilising vegetation; exposed and eroded
soil increases soil aridity; more frequent dust storms;
sand dune mobilisation
Exclusion of fire
Promotes growth of unpalatable woody shrubs at the
expense of herbage
Indirect government policies
May cause over-exploitative land use practices
Failed population planning
policies
Increases need for food cultivation, and so may lead to
over-exploitation of marginal land
Irrigation subsidies
Exacerbates flooding and salinization
Settlement policies/land
tenure
Forces settlement of nomads; promotes concentrated use of
land, which often exceeds the local carrying capacity
Improved infrastructure (e.g.,
roads; large-scale dams;
canals; boreholes)
Although often beneficial, can aggravate the problem by
attracting increased livestock and human populations or
increasing risk from salinization; possible lowering of
groundwater-table below dams and around boreholes;
silting up of reservoirs; waterlogging; promotes
large-scale commercial activity with little local benefit;
flooding may displace people and perpetuate cycles of
poverty
Promotion of cash crops and
push towards national and
international markets
Displaces subsistence cropping; pushes local people into
marginal areas to survive; promotes less resilient
monocultures; fosters expansion and intensification of
land use
Price increases on
agricultural produce
Incentive to crop on marginal lands
High interest rates
Forcing grazing or cultivation to levels beyond land
capacity
War
Valuable resources, both human and financial, are expended
on war at the expense of environmental management and
the needs of the people; large-scale migration with
resultant increased pressure on receiving areas
Natural
Extreme drought
Decreased vegetation cover and land more vulnerable to
soil erosion; creates an environment that exacerbates
over-exploitation
Extreme flooding
Loss of arable land, houses and infrastructure; displacement
of people; increased land use pressure on receiving areas
Ecological fragility
Impact of land use practices (will also depend on resilience
of environment)
