National Character Area 118
Bristol, Avon Valleys and Ridges - Natural Capital and Key Ecosystem Services
Introduction
The Bristol, Avon Valleys and Ridges 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 Bristol, Avon Valleys and Ridges NCA is contained in the ‘Analysis’ section of this website.
Note: The natural capital in this NCA is mapped below. This displays more recent national and publicly available data sets as used within Natural England’s 2020 Natural Capital Atlas Profiles.
The predominant ecosystem services in this NCA are also summarised below. The text contained in this section is based on the previous NCA profiles in 2014, and so is not entirely current. Further information on ecosystem services provided in the North Northumberland Coastal Plain NCA is contained in the Analysis: Ecosystem Services page 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:
- 14: Gloucestershire
- 34: Somerset
- 40: West of England
Note that numbers and figures in the body of the text are based on the 2014 profiles, unless otherwise stated.
Provisioning services (food, fibre and water supply)
Food provision:The Bristol, Avon Valleys and Ridges NCA supports a wide range of farming. Figures from 2009 show that 46,251 ha are covered by commercial farming, which is dominated by livestock farming. Yeo Valley foods (a national dairy producer) is based in the fertile soils north of the Mendip Hills.
Water availability: The main rivers in this NCA are the Avon, the Frome, the Chew and the Congresbury Yeo. There are also two major reservoirs that supply water within this NCA: Blagdon Lake; and Chew Valley Lake. These reservoirs are fed by springs, rivers and streams that emerge from the Mendip Hills. Blagdon and Chew Valley lakes are eutrophic due to high levels of nutrients in the water, and both lakes are designated as Drinking Water Protected Areas. The area surrounding each lake is designated a nitrate vulnerable zone (NVZ) under the Nitrates Directive. There are no major aquifers within the NCA itself. Most of the area is classed as having ‘no water available’ for additional abstraction. The reservoirs supply 1.1 million people and businesses in the Bristol area. For information regarding the current state of water availability within this NCA, refer to the Environment Agency (Abstraction Licensing Strategy).
Regulating services (water purification, air quality maintenance and climate regulation)
Regulating soil erosion: The majority of the soils in this NCA are subject to erosion where management results in a loss of stabilising vegetation, as the soil types are easily damaged. Current contributions to the regulation of soil erosion are low. The North Somerset Moors catchment priority funding statement supports measures being taken to minimise soil wash entering watercourses, prevent pathways for run-off and protect receiver watercourses. Such measures could beneficially be applied across the NCA and neighbouring NCAs.
Regulating water quality:For information regarding the current state of water quality within this NCA, refer to the Environment Agency (Draft river basin management plan maps).
Regulating water flow: While there is little or no risk of flooding across most of the NCA largely due to the flood defence works that have been put in place, there are some areas where flood risk is higher, including parts of the River Avon, the Chew Valley and the coastal settlements such as Portishead and Clevedon.
Cultural services (inspiration, education and wellbeing)
Recreation: Recreation is supported by the area s outstanding range of parks, the Forest of Avon Community Forest, the Mendip Hills AONB Partnership, the River Avon Trail, the Bristol and Bath Railway Path, The Monarch s Way, 1.9 km of the Cotswold Way National Trail and a large number of other long-distance trails and National Cycle Network routes. Overall there is a 2,200 km network of rights of way at a density of 2.56 km per km2 and around 1,000 ha of open access land covering 1.12 per cent of the NCA, which is particularly important in this highly populated area. The geology provides opportunities for caving and climbing.
Sense of history: The area retains a strong sense of its maritime past and contains a wide range of visible history across both the rural and the urban landscape, from Neolithic barrows and iron-age hill forts, to the Roman influences such as the port of Sea Mills and its architectural and parkland heritage, to the more recent industry and activity associated with mining, mills and the port at Bristol.
Biodiversity: Some 5 per cent of the NCA is covered by priority habitats (4,300 ha): 3,600 ha of this is priority woodland (lowland mixed deciduous and wet woodland), with 900 ha of reedbeds and 600 ha each of lowland meadows and coastal and flood plain grazing marsh. Some 2,000 ha (2 per cent) of the NCA is designated as SSSI; there are two SPAs, three Special Areas of Conservation, one Ramsar site and two National Nature Reserves- Gordano Valley (in part) and Leigh Woods. The majority of SSSI in the area are currently in favourable or recovering condition. The Avon Gorge SAC supports numerous rare species in its ancient woodlands.
Geodiversity: There are 27 SSSI in this NCA that are designated for their features of geological interest. These reflect the geological importance of this area. Many of these sites consist of quarries and cuttings, but there are also natural features such as the Avon Gorge and coastal exposures. Geological SSSI that contain significant fossil assemblages are a feature of the NCA.
