vit] MOORLAND ASSOCIATIONS 179 
heather (which has no underground buds) has been completely 
killed. Deschampsia flecuosa and Nardus stricta are also fre- 
quently conspicuous during the first summer after the firing, 
doubtless owing to invasion by seed. As a rule, seedlings of 
heather establish themselves immediately and in abundance 
after firmg; and, when this occurs, the complete and speedy 
rejuvenation of the heather moor is assured. The repopulating 
of the moor by heather is due to the germination of its minute 
seeds which are blown from adjoining heather-clad tracts. This 
fact is known to the keepers who therefore do not fire large, 
continuous areas in any given year. Seedlings of heather 
(Calluna vulgaris) may be found in abundance in places where 
the moor was burned during the previous year. 
Typical dry heath, which is characteristically developed on 
sandy soils throughout the lowlands of England and especially 
so in the south and east, does not occur on the Pennines. 
Graebner (1901) has shown that this association does not in 
North Germany occur in localities where the rainfall is below 
28 inches (71 cms.); and it would also appear, judging from its 
distribution in England, not to be developed where the mean 
annual rainfall is above 35 inches (89 cms.). 
The following species occur in the less wet, that is, the 
typical parts of the heather moors of the southern Pennines:— 
Dominant 
Calluna vulgaris 
Locally sub-dominant 
Erica cinerea Vaccinium Myrtillus 
Locally abundant 
Polytrichum spp. Vaccinium Vitis-idaea 
Pteris aquilina Galium saxatile 
Ulex Gallii Deschampsia flexuosa 
Empetrum nigrum Juncus squarrosus 
12—-2 
