Influence on biodiversity

SundewLarge Heath ButterflySphagnum MossQuaternary deposits by their very nature and wide distribution have the biggest influence of any geological deposits on the biodiversity of the district. These deposits and the vegetation that they now support have however been substantially modified by humans and what we see now is only a snapshot in time. Future climate change and management will have a strong influence on biodiversity.

There is significant lateral discontinuity of different Quaternary units, which contributes to changing soils and ground conditions over very small geographical areas. Possibly the unit supporting the most diverse flora and fauna is Holocene peat. The internationally important Border Mires in the Hadrian’s Wall area and other raised mires are home to a wide range of plant, insect and animal life including sphagnum mosses, sundews, bog rosemary, large heath butterfly and wading birds such as dunlin. The blanket peat habitats in the Cheviots and Cheviot fringe areas are generally less diverse but do support sphagnums, cotton grass and, at higher altitudes, cloudberry. Areas of till tend to have been cultivated over the centuries, and most of these areas are now pastureland and do not support significantly diverse ecosystems. The exceptions to this are the few remaining species-rich hay meadows (once more widespread). The free-draining soils overlying much of the glaciofluvial deposits in the Cheviot fringe have allowed widespread agriculture, hence much of the biodiversity there has been significantly modified by the actions of humans.

Clearance of natural woodland and maintaining open ground by grazing has replaced shrub and woodland by moorland habitat across large areas. This habitat characterised by Calluna heather, with other dwarf shrubs such as bilberry, cowberry and bell heather is now considered important in its own right and sites such as the Simonside Hills and Harbottle Hills are considered internationally important. In other areas grazing has reduced the vegetation to a less diverse acid grassland mosaic. Large scale post-war planting of coniferous forests in some areas has replaced natural vegetation including areas of peatland, but restructuring and felling is reversing this in some areas.