Unimproved chalk grassland is the most significant semi-natural habitat in Wiltshire and is typical of most of the south of the county and the Marlborough Downs in the north. The light soils over the chalk are ideally suited to arable farming, the steep slopes of the downland scarps and combes have largely survived the plough and the thin, freely-draining soils there still support large areas of exceptionally diverse pasture. Although most of the county’s high plains and shallower dip slopes have been cultivated, the presence of the military training area on Salisbury Plain has limited agricultural intensification and the Plain, which has been described as the largest surviving unimproved chalk grassland to the west of the Ural mountains, is protected as a Site of Special Scientific Interest (SSSI) and also a Special Area of Conservation (SAC).
There is thought to be just over 500ha of unimproved neutral grassland in Wiltshire representing 18% of the UK total. This habitat has suffered the most dramatic losses, with some sources claiming that over 98% has been lost to a combination of agricultural intensification, housing development and mineral extraction. The remaining sites are mainly small, isolated fields, which survive through the efforts of enlightened landowners who have resisted the drive to drain, fertilise or plough in the name of increased productivity. In the north of the county, although losses have been significant, there still remain some larger areas of extraordinarily diverse hay meadows which have been managed in much the same traditional way, perhaps for centuries.
Wiltshire is drained by three river systems. The southern rivers Wylye, Nadder, Ebble and Bourne all flow south into the Salisbury Avon which empties into to the English Channel. Since these rivers drain the chalk, they are characterised by very good water quality and diverse plant and animal communities and are important spawning areas for many fish species. The Bristol Avon drains West Wiltshire and passes through several towns before leaving the county near Bath. In North-east Wiltshire several streams flow in to the River Kennet, a tributary of the Thames. The Kennet and Avon Canal lies east-west across the centre of Wiltshire and marks the boundary between north and south Wiltshire.
South Wiltshire’s river valleys have substantial areas of remnant water meadows. Although these are relics of an early example of agricultural intensification, in many places they now support complex mosaics of wet neutral grassland and fen that provides a habitat for a wide range of wetland species as well as winter-feeding sites for wading birds.
The Cotswold Water Park has many of the largest standing water bodies in the county. This habitat was barely significant in the county until large-scale gravel extraction in the north (which in many cases destroyed areas of species-rich hay meadow) led to the creation of many lakes. It now provides a haven for all kinds of wildlife, but in particular for migrating birds.
Braydon and Savernake Forests are among the remnants of a number of Royal hunting forests and have some of the important woodland sites in Wiltshire. Only about 7% of Wiltshire is wooded, but around half of this is ancient woodland and over 1,000ha of Wiltshire’s woodland is protected as Sites of Special Scientific Interest (SSSI). Some of the woods have traditionally been managed as pasture-woodlands where animals graze under pollarded trees that were cut to a height of around 3m above ground to prevent browsing of new growth.
Traditional orchards are structurally and ecologically similar to wood-pasture and parkland, with open-grown trees set in herbaceous vegetation. They support a number of UK Biodiversity Action Plan (BAP) species that are rare, protected or scarce. The wildlife of orchard sites depends on the mosaic of habitats they encompass, including fruit trees, scrub, hedgerows, hedgerow trees, non-fruit trees within the orchard, the orchard floor habitats, fallen dead wood and associated features such as ponds and streams. Highlights include lichens, fungi, a host of invertebrates and birds and mammals including bats.
Although Wiltshire is not known for habitats typical of acid soils, the county does include a small, but significant part of the New Forest with its mosaic of heathland, bog, pasture woodland and close-grazed lawns with numerous ephemeral pools. Some of West and North Wiltshire’s woodlands also overly greensand geology and woodland rides and clearings support small pockets of heathland vegetation.
The urban areas of Wiltshire account for approximately 9% of the county’s area, of which over one third of the population live in Swindon. Other major towns include Salisbury, Chippenham, Marlborough, Devizes, Melksham, Trowbridge, Warminster and Westbury. The spread of urban areas inevitably brings losses and extinctions with it, yet some wildlife does take advantage such as the ‘urban fox’, which finds easy pickings from scraps in gardens and dustbins.