Harford Moor shows close correlations between landform, soil and vegetation. Fundamental to this is the convex slope profiles, making the hilltop slopes gentle and poorly drained, and the steeper lower slopes more rocky or better-drained. The paragraphs below summarise these, starting from the lower slopes.
Better-drained soils with short-grazed acid grassland and bracken
The steeper lower slopes below the Western Beacon and Wetherdon, and in patches northwards on the slopes above the Erme, have relatively well-drained granitic brown earths. The acid grassland on these drier slopes contain plentiful fescues and other sweeter grasses that provide good grazing for livestock. These help maintain the mosaic of bracken stands and open grassland (both short-grazed and longer), among which are patches of both western and common gorse. The whole area supports meadow pipit, skylark, stonechat and linnet.
Heathland on poorly drained upper-slope soils
On the gentler upper slopes, the poorer natural drainage has led to the development of gleyed (periodically saturated) soils with peaty topsoils. These carry a mosaic of grass, heather and gorse. Mature coalesced areas of western gorse habitat are important for wildlife. In some places they are protected from burning by firebreaks. Reed bunting, linnet, Dartford warbler, skylark, stonechat, dunnock, meadow pipit and willow warbler may be found here. Wheatear, skylark and meadow pipit are frequent along the open stretches of the ridge between the Western Beacon and Sharp Tor.
When hydrologically functioning, blanket bog captures and stores both carbon and water, and remains wet throughout the year. Small pools support a variety of mire species like sphagnum, and deer and cotton grasses. Molinia tends to be dominant at present, in the largely disturbed peatlands. Skylark and meadow pipit are common; snipe breed in places and the damp, rushy gullies support reed bunting.
Bracken and scattered trees – usually oak or rowan – are found in some lower valley side areas, particularly upstream of Piles Copse. These are usually on well-drained brown earths with frequent rocks. Scattered hawthorn are found in places, frequently mixed with gorse, in wetter soils and more exposed locations.
Acid grassland, rocks and tors occur in a range of upper and valley side locations. Sometimes there are extensive areas of fragmented surface rock – clitter – and sometimes the rocks are more scattered in the vegetation. Wheatear, skylark and meadow pipit are frequent around the open tors and beacons.
Whortleberry areas occur where dry, steep or rocky slopes provide some shelter. Some lower areas have bracken cover and scattered trees. In others there is a preponderance of healthy whortleberry that, if not heavily grazed, flowers and fruits, providing food for larger birds.
Valley-side mires occur where there is a varied vegetation structure around wet flushes, with both short-grazed and rank, taller vegetation. These sites support invertebrates and provide nesting and feeding opportunities for snipe; where they are more scrubby, reed bunting may also nest. Where they are in good condition, raised sphagnum bogs are found, but rushes and sometimes Molinia dominate in most cases due to grazing pressure.
Valley-bottom areas along the Erme upstream of Piles Copse tend to have been heavily disturbed by tin streaming. These support heather and whortleberry in the drier, more stony areas, and rushes or sphagnum in small mires. These niches, sometimes with scattered trees and with the river nearby, provide a wide range of habitat conditions for insects and birds. Brown trout are prolific in the river, and otters are sometimes seen.