POLYSCAPE: Multiple criteria GIS toolbox for negotiating landscape scale

ecosystem service provision

Tim Pagella1, Bethanna Jackson2, Brian Reynolds3, Colin Thorne4, Alex Henshaw4 and Fergus Sinclair5

1 Bangor University, UK2Victoria, University of Wellington, New Zealand3Centre of Ecology and Hydrology, Bangor, UK4University of Nottingham, UK5 World Agroforestry Centre, Kenya

Nile Basin Development ChallengeScience and Reflection WorkshopAddis Ababa, 4-6 May 2011

• Agricultural landscapes produce a diverse range of ecosystem services (ES) and land use change affects them.

• The spatial configuration of particular landscape features (trees, ponds, wetlands) is critical to the supply of many services.

• If we want farmers to make informed decisions, we need to help them see their farm in its landscape context, and take collective action to manage ES manifest at landscape scales (binding social capital).

• Policy makers and implementers need to be able to see and prioritise opportunities for making and managing change.

• Downstream stakeholders need to appreciate impacts of positive landscape impacts if they are to co-invest in stewardship (bridging social capital).

Background

Tool specification

• Designed explicitly as a negotiation tool

• Works at landscape scale- resolution appropriate for field decisions considering small (10 km2) to medium (1000 km2) landscape context.

• The basic algorithms can be applied using national scale (i.e. widely available) digital elevation data, land use/cover data and soil data

– Enhanced output where higher resolution data is available – e.g. LIDAR, detailed surveys.

• Layers runs in seconds to minutes - proposed interventions can be immediately evaluated

Polyscape – Implemented Arc GIS layers

Pontbren Catchment Boundary approx 25 km2

Catchment of Pontbren stream does

not map exactly to the land holding

of group members.

marginal (either because they are waterlogged or

too steep)

valuable for production services (i.e. flat and/or dry)

semi-waterlogged but flat areas

negotiable

Farm impact – plant trees on wet and sloping areas (green) not flat and dry (red); much of the catchment negotiable (orange).

Polyscape – spatially explicit multicriteria evaluation of ecosystem services

Farming impact layer (overlaid over 2006 aerial photograph)

(Slope thresholds set at 5o & 15o)

Dry Field valued by the farmer

Steep field This area is already wooded- Remnant tree cover on non-economically viable agricultural land.

Wet Field – Prone to poaching in the past

Key: marginal (either because they are waterlogged or too steep (>150) valuable for production services (i.e. flat and/or dry) semi-waterlogged but flat areas negotiable

Slope threshold set at 15o

Slope threshold set at 11o

Triangulation:

Equipment manufacturers 15o

Farmer statement >15o

Farmer practice 11o

Key: marginal (either because they are waterlogged or too steep) valuable for production services (i.e. flat and/or dry) semi-waterlogged but flat areas negotiable

Habitat connectivityplant trees to enlarge existing woodland networks (green); not where there are trees or other key habitats already (red); large area where farmers are keen to plant trees has low habitat value for tree planting (orange)

© CCW

Importance of ground truthing.

National level land cover data may contain inaccuracies at farm and field scales. CCW’s Phase 1 data overlaid over the 2006 aerial photograph for Pontbren shows missing data (and ‘simplistic’ characterisations) See: Eyecott et al 2007

Missing woodland

Missing hedgerows? Also more subtle issues – red oak and native oak both classified as

broadleaved woodland; hedgerow condition varies

Stakeholder participation in ground truthing quick, effective and important for engaging stakeholders

Trade off between farm impact and habitat networkssmall area suitable to plant trees for both farm impact and biodiversity (green); large areas excluded (red); and low value (orange)

Hydrologyhigh priority for tree planting because high flow (grassland with > 500 m2 contribution, green); Moderate Flow 100 – 500 m2; negligible flow, with <100 m2 contribution (orange); already has trees or other flow sinks (red).

Polyscape output showing the effects of the Pontbren tree planting on the farm hydrology

Flow accumulation prior to planting

Representation of flow accumulation post planting 2006

Key:

High Flow (>500m2 contribution)

Moderate Flow (100 – 500m2 contribution)

Negligible Flow (<100m2 contribution)

Sink Area

Sediment layerPlant trees to intercept sediment(green); not where there are trees or other key sinks already (red); large area where farmers may want to plant trees has low value for trapping sediment(orange)

Trade all small area where tree planting meets many criteria (green); moderate areas where new trees are either not desirable or would require large incentives to promote (red); large area dominated by tradeoffs amongst these ES or low impact (orange)

Three layers (farm productivity, hydrology and habitat connectivity) traded off against each other. Bright green areas are locations where everyone wins i.e. low productivity, intercepts water flow and sediment.

The Elwy catchment approx 100 km2

The Cambrian Mountains approx

1000 km2

The Cambrian Mountains approx

1000 km2

Conclusions• Spatially explicit tools value different parts of a landscape

differentially for each ecosystem service.• Analysis of trade-offs and synergies identify areas where it is easy to

make gains (win-win) and where incentives may be required for individuals to take action for the common good (social capital).

• Ownership of landscape views are important for tools to be used in negotiation – participatory ground truthing is effective in engaging local stakeholders (local knowledge).

• For use in negotiation, transparency of models is more important than accuracy.

• Scenario exploration can lead to co-learning and better informed decision taking.