Ecosystem Management: Concept to local-scale implementation - Facilitator Manual
How the ecosystem service concept can help make better decisions
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Transcript of How the ecosystem service concept can help make better decisions
How the ecosystem service concept can help make better
decisions
Bob Scholes
CSIR Natural Resources and EnvironmentUniversity of the Free State, 3 Feb 2012
Biodiversity or ‘Life on Earth’
Ecosystem Services‘the benefits people derive from Nature’
MA 2005 Ecosystems and human wellbeing: a framework for assessment Island Press
Human wellbeing
Material needs
Social relations
Health
Security
Freedoms & choice
A slightly modified version
Scholes et al 2010 Assessing State and trends in ecosystem services and human wellbeing. Ecosystems and Human wellbeing: A manual for practitioners. Island Press
Stocks and flows
• Ecosystem services are always flows – they have units of quantity per unit area per unit time
• The underlying resource that allows the flow to be delivered may be a stock, measured in quantity per unit area
• For example, the stock of carbon in the soil and vegetation may reach hundreds of tonnes per hectare, but it has no value…changes in the stock do. If they represent flows from the atmosphere into the land, they have a value of around R800/tonne
Bundles and simplificationsHypothesis: in any given land use most of the value is
represented by just a few services
Can you put a value on Nature?Specifically, can and should we assign a Rand value?
• A ‘common currency’ makes tradeoffs and optimisation explicit and possible to build into the price
• ‘Money talks’ – persuasive measures for development funders
• Facilitates inter-study comparisons
• Ethical questions – what is the value of a life or a species?
• Non-market services (eg the value of a view) require indirect methods which may be very unreliable
Total Economic Value has many partsScholes, RJ et al 2001 Ecosystem services and human wellbeing: A handbook for Practitioners. Ed Ash, N et al Chap4 Island Press
Total economic value often goes down with ecosystem transformation for ‘development’
– Why does this apparently irrational behaviour occur?• because private financial
benefits are often greater in the converted system, while the public costs increase even more
The ‘Natural Capital’ approach
• Natural capital is a consistent way of converting diverse flows of ecosystem services into common-metric stocks, which can be added to other measures of wealth, such as Manufactured Capital or Human Capital, to give ‘Inclusive Wealth’
• Natural Capital is the net present value of the future yields of ecosystem services
• It is a useful conceptual way of quantifying the effects of degradation
Arrow,K, P Dasgupta,L Goulder, G Daily, P Ehrlich,G Heal, S Levin, K-G Maler,S Schneider, D Starrett and B Walker 2004 Are We Consuming Too Much? Journal of Economic Perspectives 18 (3): 147–172
Despite economic growth,Africa is getting poorer
Inclusive wealth = Manufactured capital+Human Capital+Natural CapitalArrow,K, P Dasgupta,L Goulder, G Daily, P Ehrlich,G Heal, S Levin, K-G Maler,S Schneider, D Starrett and B Walker 2004 Are We Consuming Too Much? Journal of Economic Perspectives 18 (3): 147–172
Real savings,corrected for
resource depletion,
are negative
Millennium Ecosystem Assessment 2005Ecosystems and Human Wellbeing: Synthesis
Scholes, RJ 2009 Syndromes of dryland degradation in southern Africa. AJRFS 26, 113-125
Using natural capital todefine and quantify
degradation
Degradation of ecosystem services causes loss of value
– Degradation tends to lead to the loss of non-marketed benefits from ecosystems
– The economic value of these benefits is often high and sometimes higher than the marketed benefits
Timber and fuelwood generally accounted for less than a third of total economic value of
forests in eight Mediterranean countries.
You don’t strictly need to bring everything to common metrics….
…for tradeoff analysis, it is only necessary that you be able to quantify the service yield, in its own metrics, relative to a common measure of intensity of use
It is the shape of this function that matters most
Non-monetary metricsexample: greenhouse warming potential
1 t CO2 = 1/25 t CH4 = 1/298 t N20 ~ a few picoWatts/m2
0.00
10.00
20.00
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Rangefed Feedlotted
Production system
kgC
O2eq
/kg
pro
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ct
CO2 from feed production
Manure CH4
Enteric CH4 finishing
Enteric CH4 juveniles
Enteric CH4 breeding stock
Fire
Land use intensification exampleBalmford, A., R. E. Green, and J. P. W. Scharlemann. 2005. Sparing land for nature: exploring the potential
impact of changes in agricultural yield on the area needed for crop production. Global Change Biology 11:1594–1605.
Phalan, B et al 2011 Reconciling Food Production and Biodiversity Conservation: Land Sharing and Land Sparing Compared Science 333: 1289-1291.
Pre-cultivation biodiversity
Level of agricultural inputs
Bio
dive
rsity
Cro
p yi
eld
Conclusion: if you want to have a given level of agriculture, but protect as much biodiversity as possible, it is often best to have intensive agriculture on a limited area
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Degree of intensification
Re
lati
ve
eff
ec
t
Area converted
Ag inputs/area
Crop yield
In reality, intensification involves both area expansion and increased inputs per area, and they have different
consequences for biodiversity on- and off-site
Crop area * yield per area
Progressively more marginal land needs more inputs
Constructing the agricultural output curve
intensification
Area cultivated Inputs per area
Agricultural output
Building up the biodiversity loss curve
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0 0.2 0.4 0.6 0.8 1
Degree of intensification
Re
lati
ve
eff
ec
t Area converted
Biodiv index
Fragmentation
Nutrient leakageintensification
Area cultivated Inputs per area
Habitat loss Fragmentation Nutrient leakage
Freshwater biodivloss
Terrestrial biodivloss
Biodiversity Index
Relative responses to a shared fundamental driver
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0 0.2 0.4 0.6 0.8 1
Degree of intensification
Re
lati
ve
eff
ec
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Crop yield
Biodiv index
The independent axisneeds to be shared
The dependent axes do notneed to be in common units
Look at the differentials and their ratios
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0 0.2 0.4 0.6 0.8 1
Degree of intensification
dB/di
dC/di
dC/dBA B
Likely rangeNice, but doesnot meet theminimum foodproduction target
Marginal food gainsfor major off-site biodiversity impacts
Have lost much biodiv, so you may as well intensify
Is biodiversity per se an ecosystem service?
• In my opinion, generally no, with the following exceptions:– Where the biodiversity itself is the reason for tourism
• Specialist birdwatchers• Botanical tourists
– Indirectly, where biodiversity enhances a supporting service (eg primary production, pollination) or a regulating service (eg constancy of production, or suppression of pest outbreaks)
• Individual elements of biodiversity clearly provide services– All domesticated species and wild-harvested resources