Agriculture Reference
In-Depth Information
ecosystems from a productive to non-productive state due to overuse has been poorly under-
sensing has found that degraded areas were no less stable or resilient than non-degraded areas
when studying land degradation in the former homeland areas of South Africa. The produc-
tivity of these degraded areas was less, in that they produced less forage per unit rainfall than
intact ecosystems, but there was no trend or trajectory towards “desertification” or cata-
strophic reduction in ecosystem function due to over-grazing (Wessels et al ., 2004). Our
inability to quantify the risk of soil degradation to the ultimate productivity of ecosystems in
the tropics greatly reduces our ability to predict the impact of soil degradation across broad
regions of savanna in Africa, Asia and the Americas.
Markets and health services tend to buffer communities from the direct impact of ecosys-
tem degradation. Markets allow the purchasing of natural resources such as energy, food and
building materials from elsewhere, reducing the impact of local scarcity. The causal chain
from global environmental change and climate variability to health impacts is often complex
and may not be immediately observed. Land use and climate change do impact human health
directly as well as services that ecosystems provide, such as clean water or waste disposal,
which indirectly impact human health (Myers and Patz, 2009). Figure 8.1 shows a conceptual
diagram derived from Myers and Patz describing the factors that protect a community from
environmental or weather shocks.
Biodiversity and human health outcomes
Although often viewed as a “first world” concern when focused on charismatic mega-fauna
such as tigers and polar bears, biodiversity is also very important to poor populations in the
in land use
and cover
Deterioration of
Gov't safety net
protective behaviors
Regional/global ecosystem services
brought to region through trade
Population nearing vulnerability threshold
for resource constraint
FIGURE 8.1 Schematic describing the relationships between environmental conditions and
negative health outcomes, and the insulating effects of culture and society (source:
Myers and Patz, 2009).
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