Conclusions: Diversity and Ecosystem Function

• Plant production may decline as regional and local diversity declines

• Ecosystem resistance to environmental perturbations, such as drought, may be lessened as biodiversity is reduced

• Ecosystem processes such as soil nitrogen levels, water use, plant productivity, and pest and disease cycles may become more variable as diversity declines.

From: Biodiversity and Ecosystem Functioning: Maintaining Natural Life Support Processes. Naeem, S. et al. Issues in Ecology Report 4, Ecological Society of America

http://esa.sdsc.edu/issues.htm

Lyme Disease

Ecosystem Services:The Dilution Effect

Ecosystem Services• regulation of disease carrying organisms

• purification of air and water

• mitigation of droughts and floods

• generation and preservation of soils and renewal of their fertility

• detoxification and decomposition of wastes

• pollination of crops and natural vegetation / dispersal of seeds

• cycling and movement of nutrients

• control of the vast majority of potential agricultural pests

• maintenance of biodiversity

• protection of coastal shores from erosion by waves

• partial stabilization of climate / moderation of weather extremes

Why Conserve Biodiversity?

• Utilitarian Perspective– Ecosystem services or function, Potential

importance to humans.

• Ethical Perspective– Biodiversity is inherently valuable

The “Value” of Biodiversity

• “Biodiversity is not adequately protected because its value is not included in the market signals that guide . . . economic decisions . . .” – Meffe and Carroll

Market Failure

Price

Supply curve

Supply curve+ externalities

Demand curve

P P’

Q

Q’Qua

ntit

y

Economic Value

• “[The] value of an ecosystem function or service relates only to the contribution it makes to human welfare, where human welfare is measured in terms of each individual's own assessment of his or her well-being.”

Bockstael et al., Environ. Sci. Technol., 34 (8), 1384 -1389, 2000.

Calculating the Value of Nature

• Total economic value = Use Value + Option Value + Existence Value

• Use value– Direct = benefits derived from harvested resources

– Indirect = non-harvested ecosystem services

• Option value = potential benefit from future use• Existence value = intrinsic value / right to exist

Economic Benefits of Intact Natural Systems

• Traditional Uses• Forestry• Ranching• Fisheries• Crops (resistance)*• Medicine*• Waste Treatment• Public Health• Ecotourism and

Recreation• Climatic Stability

Indirect Use values

*Option values

Direct Use values

Medicine

• 118 / 150 prescription drugs used in the United States are based on natural sources (9 / top ten)– 74% plants, 18% fungi, 5% bacteria, 3% 1 snake

• The commercial value of pharmaceuticals in the developed nations exceeds $40 billion per year

• ~ 85% of traditional medicine involves the use of plant extracts (affects 80% of humans)

From: Ecosystem Services: Benefits Supplied to Human Societies by Natural Ecosystems. G.C. Daily et al. Issues in Ecology Report 4, Ecological Society of America

The Value of Fisheries

• Fish is the leading source of animal protein• The value of the U.S. freshwater sport

fishery is about 46 billion US $• The annual world fish catch is valued

between 50 - 100 billion US $• Nine of the world’s major marine fishing

areas are in decline due to overfishing, pollution, and habitat destruction.

From: Ecosystem Services: Benefits Supplied to Human Societies by Natural Ecosystems. G.C. Daily et al. Issues in Ecology Report 4, Ecological Society of America

Tragedy of the Commons

Effort

$ (R

even

ue o

r C

ost)

Cost

Revenue

Max Profit

“Bush Meat”

“The east and southern Africa region is facing a serious decline of most its wildlife populations ... the use and trade of so-called ‘bush meat’ is believed to be one of the greatest direct causes of this decline.” - TRAFFIC

Robinson, J. G., K. H. Redford, and E. L. Bennett. 1999. Wildlife Harvest in Logged Tropical Forests. Science 284:595-596.

The Value of Elephants in Kenya

• Tourists spend $200M/yr in Kenya

• Tourists rate seeing elephants as worth 13% of their trip

• Elephants in Kenya are worth $25M/yr

• Poaching has reduced elephants by 50%

• Poaching could cost $25M/yr

The Value of Ecosystem ServicesEcosystem Service Value ( Billions)

Gas Regulation 1,341

Climate Regulation 684

Disturbance Regulation 1,779

Water Regulation 1,115

Water Supply 1,692

Erosion Control 576

Soil Formation 53

Nutrient Cycling 17,075

Waste Treatment 2,277

Pollination 117

Biological Control 417

Refugia 124

Food 1,386

Raw Materials 721

Genetic Resources 79

Recreation 815

Cultural 3,015

TOTAL 33,268