PRESSURE Why birds are declining
State of the world’s birds www.birdlife.org/sowb
The conversion of natural habitats makes no economic sense once currently unmarketed ecological services are taken into account. On average, c.50% of the total economic value of natural habitat is lost following its wholesale conversion to a more intense human use.
Total economic value of relatively intact natural habitat compared to an alternative land use, for five case-studies across four biomes Tropical forest, Cameroon
NPV
Inland wetland, Canada
NPV
Plantation Intact, with small-scale farming
Intensive farming
Intact
Mangrove, Thailand
Tropical forest, Malaysia
NPV
Biodiversity is vital for sustaining human life, and yet is still being lost. Why is this? Our economic systems fail to account for the enormous value of wild nature, which can be difficult to express in monetary terms. These systems therefore favour short-term gains from converting natural capital, without considering longterm costs. The problems are made worse by global imbalances in power and wealth, perverse incentives for the destruction of natural resources, and the rise in both human numbers and individual consumption.
The perverse economics of habitat conversion
NPV
Threats to biodiversity have much deeper causes
Intact
Shrimp farming
NPV
Coral reef, Philippines
Intact with reduced impact logging
Conventional logging
Deforestation in Sumatra: what is the value of intact forest versus cleared land? (M ARCO L AMBERTINI /B IRDL IFE)
NPV = Net Present Value, in year 2000 (US$ per hectare)
SOURCE Balmford et al. (2002) Science 297: 950–953.
Intact, with sustainable fishing
MORE CASE STUDIES ONLINE
Destructive fishing
ACKNOWLEDGEMENT Figure kindly provided by Andrew Balmford (Conservation Biology Group, University of Cambridge, UK).
How much do we value wild nature? In current global markets, oil palm plantations are valued more highly than ancient forest More bird species are threatened in the developing world than the developed world People and biodiversity are often concentrated in the same areas
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