138 - Weymouth Lowlands : Natural Capital and Key Ecosystem Services

Introduction

The Weymouth Lowlands 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 Weymouth Lowlands 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:
 

• 10: Dorset

Provisioning services (food, fibre and water supply)

Food provision: There is a mixed farming pattern in the area, with arable, dairy and meat (beef and lamb) production most important. A small amount of horticulture is present and Weymouth is a fishing port supporting a small but active fishing and shellfish industry. There is a trend towards more arable and a reduction in livestock, particularly notable in relation to sheep which have experienced a 63 per cent drop in numbers.

Water availability: This NCA is important for water supply to Weymouth and further afield outside the NCA including Dorchester. The chalk and limestone geology which underlies much of the area forms primary and secondary aquifers for the supply of drinking water, being part of the larger aquifer which stretches under the Dorset Downs and Cranborne Chase NCA to the north. These aquifers have capacity for further abstraction. Surface water generally supplies fish farming and a local hydroelectric scheme. Monitoring indicates that there is abstraction capacity although this may be limited at times of low flows. 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: Wet clayey soils and thin lime-rich soils found in this area are both prone to erosion and in recent years ploughing of steep land adjacent to watercourses has led to sudden increases in sediment loads in rivers after heavy rain. This is adversely affecting water quality in some rivers and in particular increasing sediment loads in the rivers Wey and Bride. This has the potential to have an impact on aquatic SSSI such as Lodmoor and Chesil Beach and The Fleet SAC.

Regulating soil quality: Soils are intimately linked to the geology and vary from seasonally wet deep clays over clay bedrock with impeded drainage to freely draining shallow loams and shallow lime-rich soils over the limestones. Most are classified as Grade 3. Soils support biodiverse habitats such as limestone grassland on the ridges and at the coast. The soils are susceptible to both compaction and loss of organic content, particularly when ploughed, so sympathetic management is crucial.

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: Parts of the area are susceptible to fluvial and surface water flooding, particularly Burton Bradstock, Nottington and Westham in the Weymouth area. The underlying chalk and limestone geology helps to mitigate this effect where the ground is porous, although the wetter clay vales can increase surface water flow when drainage is impeded. Both Radipole and Lodmoor wetlands in Weymouth offer water storage capacity but are at risk of flooding themselves when rainfall is particularly high combined with a high tide.

Regulating coastal flooding and erosion: Large-scale erosion regulation and flooding is not provided as a service in this area as there are no features such as salt marshes which would mitigate this. However, Chesil Beach does provide a flood defence feature along much of its length, protecting farmland and communities beyond it, particularly for a discrete length adjacent to Chiswell. Coastal geomorphological processes mean that it is gradually moving inland and may well be entirely lost in the future. The coast of the NCA is of international importance, forming the central part of the Dorset and East Devon Coast World Heritage Site (the Jurassic Coast). Active geomorphological processes are one of the elements of the World Heritage Site’s Outstanding Universal Value.

In the far west around Burton Bradstock and in the east around Osmington the sea cliffs are chalk, limestone and clays of varying resistance to erosion, with differential erosion rates, resulting in the dynamic cliffs and landslides seen today. Erosion occurs with irregular cliff falls that are characteristic of the chalk and slumping of the clays and is particularly in evidence at Burton Bradstock. At Weymouth, the in-filled estuary of the Wey has been extensively built on and the beach ridge is backed by a sea wall and promenade apart from a section at the northern end of Weymouth Bay where there is a clay cliff (Furzy Cliff) which exhibits landslide activity. The Shoreline Management Plan recommends maintaining defences at Weymouth and no active intervention for the rest of the coastline. Flood risk can be exacerbated by stormy conditions raising Chesil Beach and blocking the outlet of the River Bride into the sea. This causes water levels to back up in Burton Bradstock. 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: This area has a strong identity underpinned by the Weymouth Anticline and provided by the interplay between the gently rolling landscape of rounded hills that overlooks a highly distinctive coastline and across The Fleet and Chesil Beach to the Isle of Portland. The area is part of the Dorset and East Devon Coast World Heritage Site (the Jurassic Coast) and is well recognised for its importance to geological and stratigraphical knowledge, and for its beauty, biodiversity and dynamism. The views from Abbotsbury across The Fleet and Chesil Beach have no doubt inspired and drawn many visitors to the area. Some sixty per cent of the NCA falls within the Dorset AONB and the coastline is part of Purbeck and West Dorset Heritage Coast. The development of Weymouth and Portland has been influenced by landform and distinct areas remain apparent, influencing the sense of place.

Sense of history: This area is known for its rich history, visually prominent across much of the area, and in particular it’s traditional architecture, the medieval monuments and buildings around Abbotsbury and its Second World War anti-invasion defences.

Tranquillity: Despite a drop in tranquillity from 70 per cent to 50 per cent, tranquillity still represents a significant resource in the very rural central and western parts of the NCA with its dramatic coastline and The Fleet backed by the rolling limestone hills of the Bride Valley, giving visitors and residents a sense of remoteness and openness. Weymouth at its centre continues toexpand and develop, and peri-urban development radiates out along the main access routes to Weymouth, reducing tranquillity in this area.

Recreation: This NCA is a popular destination for different users, as it provides a range of recreational experiences ranging from the more traditional beach experience of Weymouth and its various watersports opportunities to the quieter pursuit of walking the coast path. The wetlands of Radipole and Lodmoor nature reserves provide the opportunity for the local community and visitors alike to engage with nature, and visitor centres at Radipole and on Chesil Beach broaden awareness of the natural heritage of the whole area. This NCA is well supported for walking with 61 km of the South West Coast Path and 302 ha of open access land (covering more than 2 per cent of the area). Overall there is a 310-kilometre network of rights of way at a density of 2.33 km per km and 105 ha of National Trust land. The South West Coast Path traverses the whole coastal stretch and from the Isle of Portand eastwards the path is covered by the new rights afforded by the England Coast Path.

Biodiversity: This NCA is relatively rich in biodiversity with 11 per cent of it covered by BAP priority habitats. This is in part owing to its geology, coastal position and undeveloped nature. There are 867 ha of SSSI (7 per cent of the NCA) of which approximately 461 ha (3 per cent of the NCA) are SAC, SPA or Ramsar sites. There are also 481 ha of Sites of Nature Conservation Interest (4 per cent of the NCA). SSSI condition in this area is good with 92 per cent in either favourable or unfavourable but recovering condition. There is a risk that as land managers move to a more arable-based systems grassland condition will fall with reduced grazing and a consequent loss in biodiversity.

Geodiversity: The whole coastline is important for its geological interest and its educational value to coastal geomorphology and natural coastal geological processes and palaeontology. Most of the length of the coast functions naturally, with the exception of the coast around Weymouth and at Burton Bradstock where coastal defences protect settlements. The full length of this NCA’s coastline forms part of the Dorset and East Devon Coast World Heritage Site (the Jurassic Coast). It was selected for a near continuous exposure of 195 million years of geological history, for important Mesozoic fossil localities and a series of classic geomorphological structures and processes. The Weymouth Anticline forms part of the system of Alpine structures in southern Britain and is synonymous with the Purbeck Monocline, which has a similarly controlling effect on the character of the adjacent Purbeck landscape. Local limestone is the most common building stone and the use of different varieties is strongly associated with availability in the immediate area. The small and now largely abandoned quarries that were the source of this stone remain as important geological sites including SSSI and Local Geodiversity Sites.