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