Ecosystems services take to the road
By Collette Patterson, Jo Morrison and Jacqueline Fookes
Mott MacDonald has worked with Cranfield University to assess the value of an ecosystem services approach on a live road project.
Humanity benefits in a wide variety of ways from all kinds of ecosystems: agriculture, forestry, grassland, wetlands, the sea and the urban environment. We derive not only our basic needs from these systems such as clean water, food and regulation of the climate, but also cultural needs including recreation and spiritual sustenance. These benefits are collectively known as ‘ecosystem services’. They are grouped into four broad categories: provisioning (food and water); regulating, (control of climate and disease); supporting (nutrient cycles and crop pollination) and cultural (spiritual and recreational benefits). As the Landscape Institute’s Technical Information Note Ecosystem Services points out, understanding ecosystem services helps us recognise the complex interactions between the living and physical environment and people and helps us describe how the environment contributes to people’s wellbeing. Consequently, there is growing interest in ecosystem services and their potential role in guiding decisions about the planning, design and management of landscape.
An ecosystems approach provides a framework for looking at whole ecosystems in decision making, and for valuing the ecosystem services they provide. This can help ensure that society can maintain a healthy and resilient natural environment - now and for future generations. It provides a way of looking at the natural environment to understand how it works as a system and the likely impacts of a scheme on the system. While some ecosystem services are easy to measure, such as the amount of a crop grown in a given area (a provisioning service), others are harder. Provisioning and regulating services, which both lend themselves more easily to measurement and as a result , may be given more weight in the decision-making process.
Cultural services provide benefits, usually intangible, in the form of spiritual enrichment, reflection, recreation, and other aesthetic experiences. These include the landscape features that we assess and work with day-to-day but, as landscape architects, how do we ‘value’ intangibles such as scenic quality?
Landscape architects are well placed to take a creative approach to achieving the potential wider benefits of schemes. The ecosystem services approach provides a mechanism to include the externalities that are difficult to measure and quantify the ‘added value’ of alternative options/schemes. The ecosystem services approach can be used from a strategic level through to options selection and evaluation of the final scheme. In addition, the approach could be either qualitative or quantitative using monetary values.
Mott MacDonald, with Cranfield University, completed an evaluation of the existing ecosystem services and likely effects on them associated with the construction of a 20km dual carriageway, the Northern Distributor Road (NDR), connecting the A47 and the Wensum valley in Norfolk. We used InVEST, free open-source software produced by the Natural Capital Project, designed to map and value the goods and services the natural world provides to sustain human life.
The scheme was granted a development consent order in 2014 and the environmental statement, accompanying the application was supported by a separate ecosystem services assessment. Infrastructure schemes have a long gestation period, and the NDR was no different. It started life in 1992, but detailed design did not begin until 2006. The NDR scheme includes 25km of bridleways, footpaths and cycle tracks. These are separated from the highway wherever possible with associated screening and planting as part of the objective to encourage a modal shift in usage patterns. The design was developed using WebTAG, the Department for Transport's web-based guidance for design development and appraisal of transport projects. The WebTAG methodology is based on an environmental capital approach, where capital resources are grouped under the topics of landscape, townscape, historic environment, biodiversity and water environment. The environmental capital approach therefore covers many of the impacts that would be analysed using an ecosystem services approach.
The landscape design was carried out following the staged process set out in the Design Manual for Roads and Bridges (DMRB), but importantly Norfolk County Council gave a strong steer to the design team to put landscape at the heart of the design. Although we were not formally adopting an ecosystem services approach, DMRB sets out a structured methodology to the landscape design. The ecosystem services identified for the NDR corridor included high quality arable land as a provisioning service. The area is a productive landscape, due to a good climate and workable, freely draining soils. However, the soils here are nutrient poor and the landscape is productive through the uses of fertilisers and irrigation. The soils have been highlighted at risk of erosion and aquifer recharge is noted as an important need in the area. This informed the overall scheme design. For the NDR, the drainage design means that the scheme only drains into the river system directly in one location - the rest is dealt with through infiltration. This has two benefits: firstly there is no direct drainage into the Wensum Special Area for Conservation west of the scheme, thus minimising the risk of additional sediment reaching the Wensum system from the new road and secondly, surface water is returned to ground, aiding recharge of the aquifer.
Treatment of surface water run-off, through infiltration techniques involves a three-stage process to clean the run-off, with water running through grass swales and verges into lined attenuation ponds and then into a planted infiltration basins. Further, the design approach used on NDR meant instead of the usual steep sided infiltration ponds surrounded by fencing, that are a common sight along new roads, the infiltration ponds were designed to be shallow basins that did not need fencing, had ample space for marginal planting and wildflowers and allowed safe public access.
Semi-natural habitats are an important nectar source for pollinators in an arable landscape. Again this defined another scheme design aim to incorporate species rich grassland along the NDR corridor, replicating the headlands and field margins which provided diversity in the arable fields prior to construction. As well as providing nectar and pollen, the meadows sequester carbon, increase deposition of sediment in surface water run-off and are habitats for wildlife.
The InVEST Ecosystem services assessment undertaken for the NDR used data sets that had been used for the environmental impact assessment. It did not look at tranquillity or sense of place, but did have an aesthetic model as a proxy for the ecosystem service and used simple ZTV modelling based on digital terrain modelling to understand whether the scheme was visible or not. The output was qualitative as was the biodiversity model. The other services relating to agriculture, carbon, sediment, and water were quantitative.
A number of lessons were learned from the NDR project. Approximately 50% of the scheme was dedicated to native woodland, scrub and grassland on previously mainly arable land. Overall the scheme was deemed to have a positive beneficial effect in the long term, partly reflecting the belief that taking land out of arable production and creating a more diverse land cover must be positive. But the ecosystem services approach also demonstrated that the carbon and sedimentation models were key contributory factors to the positive outcome.
We found that the changes in ecosystem services supply, due to the introduction of a major road with associated green infrastructure, were dominated by the loss of the provisioning service of agricultural production in exchange for the supply of other ecosystem services through the introduction of woodland, scrubland and grassland. These changes varied however not only because of the new land uses and ecosystem service types, but also because of the initial land use and the temporal dimension defined by the time lag between the intervention to the landscape and time of assessment.
When compared with the traditional environmental impact assessment, the ecosystem services approach conducted in this study offered a possibility of appraisal of both the positive and negative impacts of the development. This offers the opportunity to look at a trade-off, for example, between food production, loss of arable land, and carbon and biodiversity. This ability to factor monetary valuations into changes to the landscape can be incorporated into cost benefit analyses. Where public funding is being applied for, for example in road schemes or flood defences, this becomes a means of justifying funding, and ensuring landscape design principles are central to the process.
In contract to an EIA, the ecosystems services approach generated a low-volume and compact report, which could model alternative options to inform the decision making process. Additionally, the modelling could be customised to generate a desired target output.
Although the ecosystem services concept can better inform conventional assessment mechanisms, by including predictions of ecosystem service delivery change induced by individual development projects, the ecosystem services approach also has the potential to revolutionise both strategic land use planning and development control by asking from the very beginning: ‘What does this landscape do for us now?’, and ‘What could it do for us in the future?’ The ecosystem services approach is also complementary to environmental legislation that concerns itself with landscape resilience.
Furthermore, linking the GIS based InVEST Model to visualisation software produces a powerful combination tool that can not only assess the land use changes, but very quickly and efficiently produce a graphic image of how they will look. This enables rapid design iterations hand-in-hand with the assessment process.
Landscape architects could lead a collaborative effort to identify a site’s ecosystem service potential and develop creative design strategies with measurable outcomes. But to do this we need to develop an understanding of soils sciences, geomorphology, water resources and ecology as well as promoting a collaborative working ethic across discipline boundaries.
Collette Patterson and Jo Morrison are landscape architects with Mott MacDonald; Jacqueline Fookes is an environmental scientist with Mott MacDonald.
J. Zawadzka and R. Corstanje: Ecosystem Goods and Services Assessment for the NDR Development. 2013. In The Norfolk County Council (Norwich Northern Distributor Road (A1067 to A47(T))) Order: Environmental Statement, Volume 2. Mott MacDonald, 2014, Chap. 13.