organic agriculture and ecosystem functions at farm and

10/7/2009

1

Organic agriculture and ecosystem

functions at farm and landscape scales

Walter Rossing, Biological Farming Systems

Outline

� Landscapes?

� Ecosystem functions / services

� Overview of effects of OA on landscape and biodiversity

� 2 Illustrations of interactions between ecosystem functions

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Landscape

� Definition: Territorial or spatial unit produced through the interaction between human societies and cultures with the natural environment (Wascher, 2000).� Many if not most of the interactions are related to

agriculture

� Inherently multifunctional: integrate various functions demanded by society.

� Classification and study according to these functions.� But: mind the interactions!

Evolution of the notion Landscape

Europe:

� Medieval times: landscape is a region, an area (physical reality)

� 16th century: landscape is an image (paintings)

� 17th century: landscape is an organized whole (science)

� 20th century: landscape is a system (science)

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Landscape as system: Ecosystem Functions

� Regulation functions: maintenance of essential ecological processes and life support systems

� Habitat functions: providing suitable habitat (living space) for wild plant and animal species

� Production functions: provision of natural resources

� Information functions: providing options for cognitive development

Source: R.S. de Groot et al., 2002

Ecosystem Functions: examples

� Regulation functions� E.g. soil retention and fertility, water supply, biological control

� Habitat functions� E.g. refuge function, nursery function

� Production functions� E.g. food, raw materials, genetic resources

� Information functions� E.g. aesthetic information, recreation, cultural & artistic info


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Land use by agriculture: Guerrero Mexico

Land use by agriculture: Guerrero Mexico

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Land use by agriculture: South Africa

Valuation of Ecosystem Functions, Goods & Services


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Environmental impacts of Organic Agriculture (OA)Aspect/IndicatorArea

Genetic diversity; Floral diversity; Faunal diversity; Habitat diversity

Biodiversity

Intensity of use; Efficiency of useEnergy

Carbon dioxide; Nitrous oxide; Methane; Ammonia

Climate and air

Nutrient use and balance; Nitrate leaching; Phosphorus; Pesticides; Pathogens

Ground and surface water

SOM and acidity; Biological activity; Soil Structure; Erosion; Desertification

Soil

Landscape structures and aesthetic valueLandscape

Source: Organic Agriculture. Kristiansen, Taji, Reganold (eds)

Assessment of environmental impacts of OA

RelativeAbsolute

++/B; +?

+?; +/B?; ?; +/B?

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+?

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na; na

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Environmental ImpactAspect/IndicatorArea

Genetic diversity

Floral diversity

Faunal diversity

Habitat diversity

Biodiversity

Intensity of use; Efficiency of useEnergy

Carbon dioxide; Nitrous oxide; Methane; Ammonia

Climate and air

Nutrient use and balance

Nitrate leaching

Phosphorus

Pesticides

Pathogens

Ground and surface water

SOM and acidity

Biological activity

Soil Structure

Erosion

Desertification

Soil

Landscape structures and aesthetic value

Landscape

Source: Organic Agriculture. Kristiansen, Taji, Reganold (eds)

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Conclusions of Environmental Assessment OA

� OA has much potential for better environmental (including landscape) performance than conventional agriculture

� Unfolding depends on motivation of farmers and financial support

� Intensification of organic agriculture is a serious threat to this positive assessment

Limitations of the assessment

� Variation in definition of OA between countries

� Different levels of control of external variation

� Variation in period of study

� Variation in spatial scale

� Variation in measures of biodiversity

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Landscape as system: Ecosystem Functions

� Regulation functions: maintenance of essential ecological processes and life support systems

� Habitat functions: providing suitable habitat (living space) for wild plant and animal species

� Production functions: provision of natural resources

� Information functions: providing options for cognitive development


Illustration 1: Information function

� How can ‘landscape quality’ be measured?

� Legibility (Readability) of the landscape: � Where am I?

� In which place?

� In which time?

� Case study� Comparison of organic farms and conventional farms

in 3 regions in NL: Hendriks and Stobbelaar, 2002

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What can you ‘read’ in this landscape?

Four perspectives to determine the readability of

the landscape

vertical

historiccycli

c

horiz

ontal

Farm image

Regional image

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The better the readability of the landscape,

the higher landscape quality

Diagnosis and development of landscape quality

Reading the landscape, current quality

Examples of goodpractice

Target image Landscape development, future quality

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Readability variables

� 4 Perspectives:� Historical cohesion� Cyclical cohesion� Horizontal cohesion� Vertical cohesion

� 3 Farm areas� Fields� Field Margins� Farm yard

Historical cohesion weak

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Historical cohesion strong

Cyclical cohesion weak

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Cyclical cohesion strong

Horizontal cohesion weak

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Horizontal cohesion strong

Vertical cohesion weak

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Vertical cohesion strong

Conclusions readability project

0255075

100V-field

Ho-field

C-field

Hi-field

V-yard

Ho-yard

C-yard

Hi-yard

V-margin

Ho-margin

C-margin

Hi-margin

Conventional farms

Organic farms

V=Vertical

Ho=Horizontal

C=Cyclic

Hi=Historic

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Conclusions readability project

� Landscape quality can be improved considerably onmany farms

� Readability of organic farms is on average betterthan that of conventional farms

� ‘Readability’ and ‘target image’ are useful conceptsfor measuring and development of the landscape quality ecosystem function

Illustration 2: Production, information & habitat

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Friesian Woodlands

50

56

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ReBdesign of the landscape TwijzelBBuitenpost

� NGO Landscape Management Friesland: enhancing connectivity and landscape identity in a rural zone of a few hundred ha.

� Based on rules of thumb.

� Can science add to this process?

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Landscape IMAGES model: approachGoal definition

Formulation of a case specific perception of

sustainability

Ecosystem modeltoolkit

Expresses system performance in terms of

indicator set

Sustainability assessment

Case specific degree of sustainability

Indicator set

Characterization of the state aspired: dimensions and thresholds

System definition

Definition of actual or alternative land use

systems

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Goal definition


sustainability

Goal definition


sustainability



indicator set



indicator set





Indicator set


Indicator set


System definition


systems

System definition


systems

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22 3344

5566

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Exploring interactions between indicators

Naturevalue

Gross margin

Pareto frontier

Solution space

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ParetoBbased multiBobjective optimization

generateby allocating

landBuse activities

evaluatefor multipleindicators

selectusing nonBweighing

ParetoBbased methods

Naturevalue

Gross marginLandscape generated in the computer

Landscape IMAGES model: approachGoal definition


sustainability



indicator set



Indicator set


System definition


systems

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Goal definition


sustainability

Goal definition


sustainability



indicator set



indicator set





Indicator set


Indicator set


System definition


systems

System definition


systems

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5566

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Indicators: Connectivity

Dispersal range

Largest connected cluster (m)Largest connected cluster (m)

Indicators: Sight lines ~ landscape identity

‘porosity’

Sight range

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Indicators

� Ecology� ↑ connectivity (spatial coherence)

� Landscape quality� ↑ variation in sight lines

� ↓ ‘porosity’ (road to road)

� ↑ ratio in length/width direction hedges (L/T ratio)

� Costs� ↓ addition of new hedges

� ↓ removal of existing hedgerows

� ↓ total length of hedgerows

(↑ maximize, ↓ minimize)

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Landscape IMAGES: maps

Plan of NGO An alternative plan: same hedgerow length and

landscape value as NGO; higher ecological connectivity

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TradeBoff results 7 indicators

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Outline B revisited

� Landscapes?� Define what you mean: spatial + temporal scales

� Ecosystem functions / services� Useful concepts for thinking on landscapeBagriculture

� Overview of effects of OA on landscape and biodiversity� Little studied; data lacking from Southern Hemisphere

� 2 Illustrations of interactions between ecosystem functions� Production, habitat, regulation, information

Thank you for your attention

organic agriculture and ecosystem functions at farm and

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