129 - Thames Basin Heaths : Natural Capital and Key Ecosystem Services

Introduction

The Thames Basin Heaths NCA provides a wide range of benefits to society. Each is derived from the attributes and processes (both natural and cultural features) within the area. These benefits are known collectively as ‘ecosystem services’. The predominant services are summarised below. Further information on ecosystem services provided in the Thames Basin Heaths NCA is contained in the ‘Analysis’ section of this website.

What is Natural Capital?

Natural capital means “the elements of nature that directly or indirectly produce value to people, including ecosystems, species, freshwater, land, minerals, the air and oceans, as well as natural processes and functions” (Natural Capital Committee, 2017).

It is helpful to consider natural capital in the form of a logic chain that represents the links between ecosystem assets, services, benefits and value to people. The figure below displays that logic chain. The quantity and quality of ecosystem assets (woodland, bogs, etc) support different types of ecosystem services, such as carbon sequestration or water filtration. These ecosystem services then provide different benefits to society, providing value for people. The figure also shows how management interventions, as well as pressures and drivers of change, influence this chain. Other capital inputs are also often needed for people to obtain the benefits from ecosystem services (a simple example is the processing of trees to produce wood products).

As an example, an area of woodland (ecosystem asset) may reduce air pollution created by traffic on a nearby road. This woodland is therefore improving air quality (ecosystem service) in the local area which results in cleaner air and improved health in the adjacent residential street (benefit). This cleaner air has a value because we know it impacts the health and wellbeing of communities.

Sometimes for ease of understanding, economic framing is used to give these benefits a monetary value. The figure below shows how natural capital assets support the provision of ecosystem services, benefits and value. The roots of the tree show how aspects of asset quality are critical to the provision of ecosystem services. The roots also show that geodiversity underpins the ecosystem assets and therefore the ecosystem services and benefits they can provide. It is important to remember that this diagram, and natural capital frameworks more generally, are a simplification of how nature works in practice.

Natural Capital within this NCA

In 2018, Natural England published ‘Natural Capital Indicators: for defining and measuring change in natural capital’ (Lusardi et al., 2018). This report identified key properties of the natural environment vital for the long-term sustainability of benefits, which can act as indicators of change.

These indicators are designed to inform our understanding of the state of our natural assets. The indicators highlight the importance of our natural assets for delivering which ecosystem service and the benefits they provide for society. The indicators and datasets identified in Natural England’s Natural Capital Indicators Project provide the foundation for the Natural Capital Atlas Profiles.

Natural England’s Natural Capital Atlas Profiles provide an “off the shelf” natural capital evidence base for each county or city region. They have a wide variety of uses with more information in the How to Start Using Your Natural Capital Atlas.

The Natural Capital indicators are presented on the map below by broad asset theme, displaying the natural capital within the NCA.

It is noted that not all indicators listed within the Natural Capital Atlas Profiles are included within the map as data is not yet available to measure them. Refer to the “Indicator Gaps and Limitations” of the Natural Capital Atlas Profiles for further information.

Natural Capital Atlas Profiles

The following Natural Capital Atlas Profiles cover counties within this NCA:
 

• 2: Berkshire
• 17: Hampshire and the Isle of Wight
• 37: Surrey
• 43: Wiltshire

Provisioning services (food, fibre and water supply)

Timber provision: Nearly a quarter (or 30,000 ha) of the NCA is wooded and, of this area, 6,500 ha is conifer plantation. There are large, long- established plantations managed to produce timber. Environmentally sustainable timber production is being developed by landowners including the Crown Estate, Forest Enterprise England and others.

Regulating services (water purification, air quality maintenance and climate regulation)

Regulating water flow: Across the NCA, there are settlements in the flood zone. The greatest flood risk is around Weybridge (on both the Wey and Thames), where there is a moderate to high risk. On the clay flood plains, there is potential for rapid run-off and consequent flash flooding. Woodland, hedgerows and grassed areas in the flood plains and on the valley sides help to slow run-off, while floodwater storage is provided by flood plain farmland and wetland habitats (including wet woodlands and reedbeds in the Kennet Valley). In contrast, the chalk geology in the west facilitates infiltration, while base flow in the chalk watercourses responds slowly to storm and drought events. Historically low groundwater levels in the Chalk have dictated low flow in these watercourses, but flooding is still possible. In the east, large settlements comprise extensive areas of impermeable surfaces, culverts and drainage, which facilitate rapid flow; where water is impeded, this can give rise to the flooding of urban and rural land. Sewage treatment works supplement flows as they pass through settlements, for example at Blackwater. Sustainable urban drainage systems manage the water and pollutants associated with new developments and roads.

Cultural services (inspiration, education and wellbeing)

Sense of place/inspiration: Within the context of south-east and its proximity to west London, this NCA is significant for its large areas of informal greenspace -heathland and woodland supporting international biodiversity interest – and its variety of recreational opportunities, accessible thanks to the major road network. There is a well-recognised wartime heritage associated with Aldermaston, Aldershot and Greenham. Woodland is a dominant feature of the NCA, with nearly a quarter of it being wooded (this includes large conifer plantations).

Recreation:The area of formal and informal greenspace is considerable in the east, offering a wide range of opportunities to the large conurbations around Camberley – and also to visitors from further afield, with major road links such as the M3 link to west London. Around 9 per cent of the NCA (or 10,000 ha) is accessible to the public; much of this is woodland and heathland, including common land, where visitors can enjoy a range of wildlife. There are further rights-of-way routes in the wider countryside. Water-filled gravel pits, canals and rivers allow for fishing and boating. Private estates and local authorities across the NCA manage green spaces, with facilities and activities (including cafes, visitor centres and school visits) catering for tourists.

Biodiversity: A large part of this NCA is protected for its habitat and species interest: features range from chalk river and reedbed to ancient woodland and acid grassland. A complex of sites totalling an area of 8,500 ha (or 7 per cent of the NCA) incorporates the South West London Waterbodies SPA and Ramsar site; the Thames Basin Heaths SPA; the Thursley, Ash, Pirbright and Chobham SAC; the Kennet Valley Alderwoods SAC; and the Kennet and Lambourn Flood Plain SAC. Around 11,000 ha of the NCA are designated as SSSI, and another 12,000 ha are covered by Local Wildlife Site designations. The area is readily associated with woodlands, while visitors to the heathlands can enjoy flowering heather, dragonflies and ‘churring’ nightjars.

Geodiversity: Sands and gravels are distinctive of this landscape, and are made prominent along heathland public access routes. They are also evident in the long-established and ongoing presence of the aggregates industry, as it works or restores extraction sites. The local town of Bagshot gave its name to the Tertiary strata known as the Bagshot Beds. In the west, the escarpment of the Hampshire Downs incorporates the highest chalk hill in the country, and is part of the North Wessex Downs AONB. Historic buildings are constructed from brick and tile, made from locally quarried aggregates and clay.