POLYSCAPE: Multiple criteria GIS toolbox for negotiating landscape scale ecosystem service provision
Nile Basin Development ChallengeScience and Reflection WorkshopAddis Ababa, 4-6 May 2011<br />POLYSCAPE: Multiple criteria GIS toolbox for negotiating landscape scale ecosystem service provision<br />Tim Pagella1,Bethanna Jackson2, Brian Reynolds3, Colin Thorne4, Alex Henshaw4 and Fergus Sinclair5<br />1 Bangor University, UK<br />2Victoria, University of Wellington, New Zealand<br />3Centre of Ecology and Hydrology, Bangor, UK<br />4University of Nottingham, UK<br />5 World Agroforestry Centre, Kenya<br />
Background<br /><ul><li>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).</li></li></ul><li>Tool specification<br />Designed explicitly as a negotiation tool<br />Works at landscape scale- resolution appropriate for field decisions considering small (10 km2) to medium (1000 km2) landscape context.<br />The basic algorithms can be applied using national scale (i.e. widely available) digital elevation data, land use/cover data and soil data <br />Enhanced output where higher resolution data is available – e.g. LIDAR, detailed surveys. <br />Layers runs in seconds to minutes - proposed interventions can be immediately evaluated<br />
Pontbren Catchment Boundary approx 25 km2<br />Catchment of Pontbren stream does not map exactly to the land holding of group members.<br />
Polyscape – spatially explicit multicriteria evaluation of ecosystem services<br />Farm impact – plant trees on wet and sloping areas (green)not flat and dry (red);much of the catchment negotiable (orange). <br />valuable for production services (i.e. flat and/or dry)<br />semi-waterlogged but flat areas<br /> negotiable<br />marginal (either because they are waterlogged or too steep)<br />
Farming impact layer (overlaid over 2006 aerial photograph)<br />(Slope thresholds set at 5o & 15o)<br />Steep field <br />This area is already wooded- Remnant tree cover on non-economically viable agricultural land.<br />Dry Field valued by the farmer<br />Wet Field – Prone to poaching in the past<br />Key:<br />marginal (either because they are waterlogged or too steep (>150)<br /> valuable for production services (i.e. flat and/or dry)<br /> semi-waterlogged but flat areas<br /> negotiable<br />
Key:<br />marginal (either because they are waterlogged or too steep)<br /> valuable for production services (i.e. flat and/or dry)<br /> semi-waterlogged but flat areas<br /> negotiable<br />Triangulation:<br />Equipment manufacturers 15o<br />Farmer statement >15o<br />Farmer practice 11o<br />Slope threshold set at 15o<br />Slope threshold set at 11o<br />
Importance of ground truthing.<br />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 <br />Missing woodland<br />Also more subtle issues – red oak and native oak both classified as broadleaved woodland; hedgerow condition varies<br />Missing hedgerows?<br />Stakeholder participation in ground truthing quick, effective and important for engaging stakeholders<br />
Trade off between farm impact and habitat networks<br />small area suitable to plant trees for both farm impact and biodiversity (green); large areas excluded (red);and low value (orange)<br />
Hydrology<br />high 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).<br />
Key:<br /> High Flow (>500m2 contribution)<br /> Moderate Flow (100 – 500m2 contribution)<br /> Negligible Flow (<100m2 contribution)<br /> Sink Area<br />Polyscape output showing the effects of the Pontbren tree planting on the farm hydrology<br />Flow accumulation prior to planting<br />Representation of flow accumulation post planting 2006<br />
Sediment layer<br />Plant 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)<br />
Trade all <br />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)<br />
The Elwy catchment approx 100 km2<br />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.<br />
Conclusions<br />Spatially explicit tools value different parts of a landscape differentially for each ecosystem service.<br />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).<br />Ownership of landscape views are important for tools to be used in negotiation – participatory ground truthing is effective in engaging local stakeholders (local knowledge).<br />For use in negotiation, transparency of models is more important than accuracy. <br />Scenario exploration can lead to co-learning and better informed decision taking.<br />