149 - The Culm : Natural Capital and Key Ecosystem Services

Introduction

The Culm 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 Culm 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:
 

• 6: Cornwall and the Isles of Scilly
• 9: Devon
• 34: Somerset

Provisioning services (food, fibre and water supply)

Food provision: The area is characterised by its dairy production, and is also a producer of quality beef cattle, including traditional Red Ruby, and lamb. The sections of arable land in the south-east of the NCA also contribute to food provision through cereal production.

Timber provision: The relatively high proportion (13 per cent) of woodland in this area is not reflected in the availability of timber. Much of the woodland is located in the very difficult to access coastal combes and steep-sided valleys of the Taw and Torridge; however, plantations at the centre of the area have the capacity to produce both hard and soft wood in significant volumes.

Biomass energy: Existing woodlands and hedgerows are being brought under sympathetic management with potential for some biomass production as a by-product of commercial timber production. Opportunities for growing miscanthus do exist, where not in conflict with Culm grassland sites and below- ground heritage assets, with high potential yields identified across the area.

Water availability: Most of the area is classified as having additional water available for abstraction, although the NCA contains some areas that either have no water available for additional abstraction or are already over-abstracted. There are two reservoirs in the NCA: Upper and Lower Tamar Lakes, and Roadford Reservoir. In the Taw and Tamar catchments the main abstractions are for public water supply, agriculture, aquaculture and hydroelectric power (although in the latter case only small sections of river experience reduced flow). Within the North Cornwall catchment, the main abstraction (making up 50 per cent) is for hydroelectric power generation, followed by aquaculture. 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 soils in this NCA are medium to heavy soils that are at only limited risk of erosion. They are most at risk on steeper slopes under cultivation, and as a result of high rainfall. The upper reaches of the Tamar within this NCA down to Launceston fall within a Department for Environment, Food and Rural Affairs (Defra) priority catchment area, due to the high rates of sedimentation. The gently-sloping terrain, with its predominantly loamy or slowly permeable clay soils, has moderate to high run-off potential, with rates of surface flow leading to soil erosion and sedimentation within waterbodies (Defra priority catchments identified under the England Catchment Sensitive Farming
Delivery Initiative, DEFRA). In addition, these soils have limited potential for increasing organic matter levels by management interventions, because levels are already likely to be high.

Regulating soil quality: The freely-draining, slightly acid, loamy soils, covering 55 per cent of the NCA, have good water infiltration where the soil structure is good. The slowly permeable, seasonally wet, acid, loamy and clayey soils (24 per cent) are easily damaged when wet, and are at risk of causing diffuse pollution and flooding as a result of poor water infiltration. In addition, these soils have limited potential for increasing organic matter levels by management interventions

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: Impermeable rocks and steep gradients in the upper catchments give the rivers a ‘flashy’ nature, which can cause rapid flooding downstream after heavy rainfall, particularly when this coincides with high tides in the estuaries and at outfalls (North Devon Catchment Flood Management Plan, Environment Agency, 2009). There is high fluvial flood risk along the coast in East Cornwall (as demonstrated by the 2004 flooding of Boscastle, on the border between this NCA and the Cornish Killas, and the 2012 flooding of Clovelly), where the watercourses rise on high ground in small catchments and flow rapidly downhill in deep, narrow valleys directly to the sea (East Cornwall Catchment Flood Management Plan, Environment Agency, 2009).

Regulating coastal flooding and erosion: Rates of cliff erosion are generally slow and beaches are likely to maintain their current form with continued inputs. Localised problems may occur where cliff erosion undermines the South West Coast Path and coastal car parks. The Shoreline Management Plans for both Cornwall and the Isles of Scilly and for North Devon have recommended active and uninterrupted erosion, to allow natural processes to evolve along much of the coast. For information regarding current shoreline management within this NCA, refer to the Environment Agency (Shoreline management plans).

Cultural services (inspiration, education and wellbeing)

Sense of place/inspiration: A sense of place is derived from the pastoral character: open, rolling ridges, intimate river valleys and the distinctive Culm grasslands on commons, unenclosed ground and unimproved pasture, with blocks of both deciduous and coniferous woodland. The coast is defined as Heritage Coast and falls within the North Devon AONB. It is dramatic and striking, varying from low-lying levels, long sandy beaches and sand dunes, to high cliffs and sheltered coves, and incorporating picturesque, traditional fishing villages.

Sense of history: There is a wealth of visible prehistoric remains, including bronze-age barrows and prominent hill forts. Medieval wayside crosses are another characteristic element of the landscape, together with a high proportion of medieval houses by national standards related to the medieval pattern of dispersed settlement and early enclosure. Settlement is simple and timeless in character.

Tranquillity: The area remains a national ‘island of tranquillity’, largely undisturbed by major development or roads. Only a small proportion (1 per cent) of the area is urban and only local intrusion occurs around the few towns and adjacent to the few major roads.

Recreation: Recreational opportunities are provided by 112 km of the South West Coast Path National Trail, the National Cycle Network, and numerous regional routes including the Tamar Trail, Tarka Trail, Two Castles Trail, Two Moors Way, West Devon Way and Ruby Trail.

Biodiversity: Some 3,500 ha of the NCA, or 1.2 per cent, is designated as a Site of Special Scientific Interest (SSSI), and there are four Special Areas of Conservation (SAC) within the area. Almost 6,000 ha of the NCA are covered by Biodiversity Action Plan (BAP) priority woodland – upland oak, lowland mixed deciduous, lowland beech and yew, and wet woodland. There are almost 3,000 ha of purple moor grass and rush pasture – this is one of the last strongholds of Rhs pasture or Culm grassland in Britain. The area boasts internationally important populations of marsh fritillary butterfly, and nationally important populations of willow tit and dingy mocha moth. The rivers in the area, the Taw, Torridge and Tamar, provide important habitats for salmonids, and also the most southerly population of freshwater pearl mussel. The coastal fringe of the NCA is important for maritime cliff and slope BAP habitat, consisting of steep (often wooded) slopes and important geological exposures.

Geodiversity: The underlying geology of the area determines and influences the soils, drainage, and many of the habitats and human activities found across the area. The ability to observe, record and interpret geological formations and geomorphological processes, particularly along the coast, is an important contribution to education. Dramatically folded strata are exposed along much of the coastline and this is one of the most distinctive elements of this landscape.