Biodiversity and Ecosystem Services in Multifunctional Landscapes
The Wessex Chalk landscape in southern England comprises 1400 km2 of open, rolling chalk land with small hilltop woodlands and rivers within narrow floodplains. This landscape contains a mix of productive arable land, extensively managed grassland undergoing biodiversity restoration and high nature conservation value, ancient grasslands. It is an exceptional prehistoric ritual landscape with widespread earthworks and monuments.
Species-rich grassland found in this region accounts for c. 50% of the total calcareous grassland resource in the UK. The majority of the chalk grassland is associated with Salisbury Plain and Porton Down, the largest expanse of chalk downland remaining in north-west Europe. These sites are designated as UK Sites of Special Scientific Interest, and European Special Areas of Conservation and Special Protection Areas for birds. The grasslands are amongst the most biodiverse in northern Europe, supporting exceptional numbers of plant, insect and bird species. The chalk streams of the landscape have high ecological value, particularly the River Avon System SAC and SSSI. They are valued for rich aquatic plant communities, diverse fish assemblages (incl. priority species Salmo salar and Cottus gobio), and for their aquatic invertebrate fauna, including many species with a restricted distribution within the UK.
Multiple ecosystem services are delivered by this landscape. Intensively managed arable and improved grassland is the major land use (62%). The flat chalk soils are amenable to cultivation in autumn or spring, making them ideal for intensive cereal production with consistent high yields of 8-10 t ha-1. In the absence of intensive agriculture, the low inherent fertility of these soils also makes them highly suitable for restoration of diverse plant communities. The UKNEA concluded that the biodiversity of such grasslands is likely to be important in providing a number of ecosystem services such as crop pest control and pollination, and carbon sequestration. Unlike most remnant chalk grasslands which are restricted to steep slopes and thin soil, much of this grassland occurs on relatively deep and fertile soils making it moderately productive for extensive agriculture. This offers an opportunity to measure services along a biodiversity gradient of grasslands on the same soil type. Recreation is an important cultural service, with over 2.8M visits to the area each year spending in excess of £180M. The clean rivers are also valued for their recreational fisheries (trout, salmon and grayling).
A ‘natural experiment’ - An exceptionally high proportion of the Wessex Chalk (10%) is undergoing ecological restoration. Much of this is funded by the agri-environment schemes, with effort coordinated and targeted by initiatives led by project partners, in particular the RSPB Futurescapes Programme, the Wildlife Trusts, and Syngenta’s Operation Pollinator. The Hampshire Avon DTC is a large-scale experimental platform to determine if multiple on-farm mitigation measures can reduce the impact of agricultural pollution on rivers while maintaining food production. The platform has established a detailed sensor network to trace pollutant (nutrients, sediment, organic matter) pathways from agricultural catchments to rivers. Together these efforts provide a unique opportunity for us to work with practitioners on a practical ‘natural experiment’ to examine critically the role of biodiversity on the provision of ecosystem services across a multi-functional landscape. In particular the gradient of land use intensity with diminishing natural capital from the ancient grasslands areas, through the restoring grassland to the intensive agriculture is reflected in both local plant and insect diversity effects, and broader landscape effects on pollinators and river invertebrates, as well as functions such as carbon stores.
