Dry heath typically occurs on higher levels of fertile acid sands and gravels that drain freely with the falling rain water passing quickly through the soil to the peat layer below and down towards wet heath and eventually valley mire and bog. Being such difficult conditions for plants to grow dry heathland is dominated by specialist plants such as heather and gorse. Open dry heath is dependant on some form of intervention management in the form of grazing, burning or clearing to stop regeneration by scrub and eventually tree species such as birch and Scots pine.
There are various types of dry heath but analysis of these is rather for the experts and I choose to pit them all into one heading but as you visit various areas of heath you start to notice that, contrary to popular belief, heathland habitat is, indeed, quite variable in subtle ways. For example, north of Poole the dominant heather is ling whereas south of Poole it is the deeper purple of bell heather than is dominant. Again, to the north of Poole there is quite a lot of western gorse whereas to the south European gorse is more common. The dwarf gorse is more widespread to the north of Poole although is frequent to the south.
Within any dry heath areas there are going to be variations as well where, for example, worn paths expose the sand below. his is where some of reptiles thrive along with ground nesting bees, wasps and beetles. Gorse scrub can establish in some areas, a home for Dartford warblers, and elsewhere scattered birch and Scots pine may become established which are beneficial to woodlark, tree pipit and nightjar.
Lowland dry heath is an internationally endangered habitat but, thankfully, although much has been lost in the last fifty years or so, there is still a good amount left in Dorset.
Under the Phase 1 habitat survey classification system dry dwarf shrub heath is coded as D1 and is described as follow:
"Vegetation with greater than 25% cover of encoids or small gorse species in relatively dry situations. Calluna vulgaris (ling). Vaccinium myrtillus (bilberry), Erica cineraria (bell heather), Ulex minor (dwarf gorse) and Ulex galli (western gorse) are typical of lowland dry dwarf shrub heath. Acid heaths usually occur on deep podsols developed on base-deficient sands, gravels and clays. Basic heaths are much more restricted in extent and may be recognised by the presence of herbs characteristic of chalk grassland and open habitats. "
Under the National Vegetation Classification system dry heath is classified primarily as H1-4, H6, H8-10 and H12-22.