Ecosystem Services - Ecological Systems - page 93

mosquito vector that transmits the parasite that causes malaria. On the other hand,
destruction of other systems can have sharp negative consequences for human
health. There is emerging evidence that loss of tropical forests, for example, leads
to an increase in transmission of malaria [ 1 , 50 ]. Similarly, fragmentation of, and
biodiversity loss from, eastern North American forests is associated with an
increase in lyme disease [ 32 ].
Natural and managed ecosystems provide many services that sustain human
health, through provision of human nutrition (especially of protein and
micronutrients); purification and regulation of drinking water; regulation of air
quality; regulation of vector-borne disease; and psychological benefits. There is
a great need for research illuminating the links between biodiversity, ecosystem
conditions and processes, and human health.
Trade-offs and Synergies
The relationship between ES and biodiversity and among different ES varies with
socio-ecological context. In some cases, clear trade-offs and synergies among services
have been defined in specific contexts [ 54 ], but there is still much to be learned about
what determines the nature of these relationships. Advancing this knowledge is
essential because policies addressing management change can only be successful if
management controls ES relationships. If policies are established to align multiple
ecosystem services, but biophysical conditions in the system lead to innate trade-offs
among services, management changes are bound to fail in delivering the desired
improvements to social benefits.
Distributional Effects
Much of the science of mapping ES has focused on identifying where ES are
generated and where they are delivered. However, less work has focused on
identifying to whom ES actually flow. This connection is essential if policies
addressing ES delivery are to be equitable and either improve the well-being of
the poor or avoid unintended distributional consequences. Past work in this arena has
focused on overlaying maps of ES provision with an array of poverty indicators (e.g.,
[ 68 ]). Missing from this spatial analysis is information on access to and ability to
control the delivery of ES. In many cases (e.g., for services such as clean drinking
water, hydropower production, agriculture, water for irrigation, wave power gener-
ation), the actual delivery of services to specific people is affected by the location of
infrastructure or institutions regulating access to resources. New science is needed
that allows the ready mapping of these connections and the prediction of how they
will change under future conditions.