3: 
Ny 
Iv] GRASSLAND ASSOCIATIONS 121 
the ecological relations show scarcely any perceptible alteration ; 
and the soi-disant ‘formations’ everywhere pass imperceptibly 
one into another” (Gradmann, 1909: 92). This criticism of a 
method of classifying plant communities goes to the root of 
the matter; and the point of view which Gradmann here states 
with lucidity and vigour is precisely the point of view which 
the British school of plant geographers has definitely adopted. 
On bare slopes, where the soil is very dry, shallow, and 
calcareous, the dominant grass (Festuca ovina) tends to become 
much less abundant; and small plant societies, dominated by 
such species as Brachypodium gracile, Lotus corniculatus, and 
Thymus Serpyllum become numerous and abundant. 
The vegetation of the marshy places of the limestone slopes 
is described in Chapter VI. 
Mixed Calcareous Grassland 
On ascending a steep slope of calcareous pasture in one of 
the limestone dales, it is found that, at an elevation of about 
1000 feet (805 m.), it opens out on to a plateau of upland 
cultivation. From this plateau, rounded hill-summits rise, the 
highest of which, on Bradwell moor, reaches an altitude of 
1550 feet (472 m.). On the lower portions of the limestone 
plateau, calcareous pasture may occur; but this is here fre- 
quently fenced by characteristic white walls of loose blocks of 
limestone. The walls indicate that some attempt has been 
made to reclaim the land, and that regular grazing takes place. 
Where the land has been ploughed at least once, and cultivation 
continued, either permanent pasture or arable land still occurs 
(see Chapter VIII); but if the land has never been ploughed or 
if it has lapsed from cultivation, a type of grassland occurs 
which is related to the primitive calcareous grassland. Sheep, 
cattle, and horses may be frequently grazed over it; and thus 
those plants of the calcareous grassland which cannot endure 
a high nitrogen content of the soil die off, while the rest remain. 
A few other plants which tolerate the manuring of the soil 
invade the pasture; and thus a type of grassland occurs which 
is, in a general way, related to the “Fettwiesen” of the Swiss 
plant geographers (cf. Brockmann, 1907: 332; Riibel, 1911: 
143). 
