Reconsidering the concepts

of ecological quality

Achim PaetzoldAchim Paetzold

“Ecological health is a nebulous concept that

should be expunged from the vocabulary. Likewise,

all synonymous terms are ridiculous in a scientific

context.”

Jill Lancaster (2000)

Ecological quality – why?

Clear definitions of quality is needed for

• environmental legislation, e.g. WFD

• target for ecosystem management and restoration

• environmental impact assessment

Existing concepts

Ecological / biological integrity

WFD, Clean Water Act USA

Ecosystem health

Rio Declaration on Environment and Development 1992

Ecosystem goods and services

Millennium Ecosystem Assessment (UNEP coordinated)

Ecological / biological integrity

“ the capability of supporting and maintaining a balanced, integrated, adaptive community of organisms having species composition, diversity, and functional organization comparable to natural habitats of the region” (Karr & Dudley 1981)

“Natural”

“Natural” can be defined as being without

• human influence

• human technology

agriculture

wood

wetland

Integrity of created wetlands

Biological integritylow high

agriculture wood

wetland

low high

Integrity of created wetlands

Biological integrity

Advantages

• defined target

• existing indicators (e.g. IBI)

Problems

• characterisation of natural reference state is problematic

• long term and large scale changes of the environment

• world is dominated by humans

Ecological integrity

Ecosystem health

“ a healthy ecosystem is defined as being stable and sustainable, maintaining its organization and autonomy over time and its resilience to stress” (Haskell et al. 1992)

Ecosystem health is defined by the lack of change in system organization and functioning.

Key attributes of ecosystem health (analogy to human health):

Ecosystem health

• vigour (productivity)

• organization (biodiversity)

• ability to resist or recover from stress

Rapport et al. (1998)

Ecological quality and society valuation

• no intrinsic optimum state of an ecosystem

• societal decision whether ecosystem state is good or

bad

• society decides whether “naturalness” has primacy

Ecosystem services

“ the conditions and processes through which ecosystems sustain and fulfil human life”

Millennium Ecosystem Assessment (2003)

Valuation of ecosystem services

• valuation of ecosystem services are context dependent

• societal demands need to be integrated

Valuation of ecosystem services

• valuation of ecosystem services are context dependent

• societal demands need to be integrated

• status of an ecosystem service is the ratio of provision to demand

Provision

DemandFlood protection

0.21.0

Valuation of ecosystem services

• valuation of ecosystem services are context dependent

• societal demands need to be integrated

• status of an ecosystem service is the ratio of provision to demand

0.21.2

Provision

DemandFlood protection

Ecosystem services profile (ESP)

0

20

40

60

80

100

Floodprotection

Drinkingwater

Fishproduction

Biodiversity

provision

demand

Ecosystem services

0

20

40

60

80

100

Floodprotection

Drinkingwater

Fishproduction

Biodiversity

provision

demand

0

0.5

1

1.5

2

2.5

Floodprotection

Drinkingwater

Fishproduction

Biodiversity

ES

QE

SP

agriculture wood

ESP of created wetlands

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Floodprotection

Nutrientattenuation

Biodiversity Climateregulation

ES

P

agriculture wood

ESP of created wetlands

ES

P

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Floodprotection

Nutrientattenuation

Biodiversity Climateregulation

agriculture wood

ESP of created wetlands

ES

P

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Floodprotection

Nutrientattenuation

Biodiversity Climateregulation

Challenges

• identify demands for ecosystem services (incl. future

demands)

• develop indicators for ecosystem services

• define the scale / boundaries for assessment

• identify interdependencies among ecosystem services

Conclusions

• quality of an ecosystem is a societal judgement

• ecological quality can be defined by the overlap between

ecosystem services provision and demand profile (ESP)

• ESP fosters integrative approach to ecosystem management

Defining ecosystem services

Wetlands, infiltrationRetention of water Avoidance of flood damage

Instream productivityWater qualityPhysical habitat

Water bodyTarget fish populationAdjacent landscape

Recreational angling

Ecosystem function/ component

Ecosystem serviceBenefit

Resilience

Resilience has been defined as

rate at which a system approaches steady state after perturbation

as the capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity and feedbacks

Human valuation standards

• aspects of human utility

• respect or virtue (moral, religion)

• precaution

Provision

DemandFlood protection

Fish production

Biodiversity

Drinking water supply

Interdependencies of ecosystem services