The Value of Hedgerows: Application of Natural Capital and Ecosystem Services at the Landscape scale

Overview

Man-made field boundaries including linear woody features (hedgerows, windbreaks, and shelterbelts) are common rural features in many countries around the world. The number of fields and the field density (the number of fields per km2) has decreased throughout the UK due to the removal of field boundaries. The Countryside Survey mapping shows that between 1984 and 2007 nearly 110,000 km of hedgerows were destroyed and there are now only 402,000 km of managed hedgerow in England. The removal of hedgerows creates larger fields which encourage the propagation of runoff, due to longer flow pathways. This can lead to increased runoff velocities and greater soil erosion. However, the impact that individual hedgerows may have in terms of storing water, slowing the flow, breaking up flow paths is largely unknown, due to a lack of monitoring data. Environmental policy is now encouraging hedgerow planting, and these schemes funded the creation and restoration of 27,000 km of hedgerows from 1991-2012 (Barr et al., 2010).

Hedgerows provide multiple ecosystem services to society, such as through cultural value, biodiversity and providing a barrier to sediment and water. However, some of these impacts have been researched more than others, with multiple studies on the ecological value, but far fewer on the benefits on the water system.

This project will focus on quantifying both the impact of hedgerows on the different ecosystem services through field experimentation and the value of hedgerows through using the Natural Capital accounting frameworks.

The UK Government’s 25 Year Environment Plan (www.gov.uk/government/publications/25-year-environment-plan) uses the framework of Natural Capital, which is defined as “the elements of nature e.g freshwater, land, soils and air, which directly or indirectly bring value to people”. This builds upon the Ecosystem Services approach, which can be classified as provisioning (water supply), regulating (climate resilience), supporting (nutrient cycling), and cultural (recreation).

The specific objectives of this project are:
1) Develop a conceptual model of the ecosystem services provided by hedgerows
2) Map hedgerows at the national scale through time using OS historical maps and open source remote sensing imagery.
3) Quantify the benefits of hedgerows on ecosystem services which have seen less attention i.e. flood mitigation, soil erosion, at the individual and network scales.
4) Value the benefits of hedgerows for society through Natural Capital accounting tools.
5) Determine whether different types of hedgerows provide different benefits and values.

Methodology

This project will utilise a mixed methods approach, combining field monitoring, numerical modelling and environmental economics.

GIS and Remote Sensing software will be used to map hedgerows nationally at different periods through time to quantify their loss. This will build on the work of Sullivan and Scholefield (2017). Furthermore, the beneficiaries of Natural Capital are spatially disconnected from assets, leading to underestimation of the ecosystem benefits. You will use the Spatial Analyst tools in Arc GIS to map the spatial/temporal flows/links to get a more complete picture of the beneficiaries to allow investors to make more informed decisions.

Field experiments will be conducted to quantify the benefits hedgerows provide to ecology and hydrology. This will consist of biodiversity surveys of flora and fauna, and monitoring of soil properties. This will build upon the research of a previous PhD student, who focussed on the benefits of hedgerows on flood mitigation. Novel experiments will be designed where we can assess the role of a network of hedgerows rather than individual features. Various field sites will be studied, including the one used by the previous student in Yorkshire. However, different types of hedgerows, including ones associated with stonewalls (Cornwall), ditches, urban, and with differing plant species compositions, will be considered.

Finally, a wide range of stakeholders will be engaged in the research, including landowners, tenant farmers, contractors, and environmental managers. Online questionnaires and Interviews will be used to understand current activity and barriers to “payment for services”. Using Environmental Economics, the value of services and assets will be estimated, using the Total Economic Value concept accounting for use, non-use and option values e.g. water resources, biodiversity and future generation preferences respectively.

Project Timeline

Year 1

Undertake a comprehensive literature review and develop detailed project objectives, particularly around the development of the ecosystem service hedgerow conceptual model, and design experiments to quantify the different services provided in the field.

Year 2

Continue field monitoring of hedgerows at different field sites and undertake complementary experiments to assess different services. Carry out surveys to quantify other benefits.

Year 3

Finalise data collection and conduct economics analysis. Work closely with stakeholders to ensure key messages are translated into practice.

Year 3.5

Thesis writing and publications

Training
& Skills

In addition to the core training provided by IAPETUS2, you will undertake specific training on GIS will be provided by the supervisors and through dedicated courses arranged by HR Wallingford. You will also attend a Summer School, led by British Ecological Society. The student will get the opportunity to present their research at a range of national and international conferences, to build communication and networking skills. You will be a member of the Water Group at Heriot-Watt, which run a series of seminars and training workshops.

References & further reading

Sullivan M J.P.; Pearce-Higgins J W.; Newson S E.; Scholefield P; Brereton; 2017, A national-scale model of linear features improves predictions of farmland biodiversity. Journal of Applied Ecology, 54 (6), 1776-1784.

Further Information

Dr Ian Pattison
Institute of Infrastructure and Environment, EGIS, Heriot Watt University
i.pattison@hw.ac.uk

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