II] WOODLAND ASSOCIATIONS 49 
more advantage in colonizing cleared or partially cleared areas 
than the large and heavy fruits of the oak. In some such places, 
seedlings of the birch are extremely abundant; and local plant 
societies of well-grown birches are common in many of the oak 
woods. A birch wood at low altitudes in this district usually 
represents a degenerate oak wood which has been colonized by 
birches. In ascending the cloughs, many of which are now 
almost treeless, isolated plants of the common birch are often 
the last trees which are encountered. Under the peat of the 
moors, birch remains are locally very abundant. 
The white birch (* Betula alba) is perhaps not indigenous 
in the hilly woods of the Peak District, as it only seems to 
oecur in the company of such obviously planted trees as the 
beech, sycamore, peduncled oak, larch and pine. It is never 
abundant; and it is absent over extensive tracts and from the 
more primitive and the more upland woods. 
The alder (Alnus glutinosa) is confined to stream sides 
and marshy places, where it often forms small societies. It is 
more abundant in the oak woods than in the ash woods, 
The beech (* Fagus sylvatica), although an almost invariable 
constituent of the larger woods, has little claim to rank as 
indigenous. As a rule, evidences of its introduction are easy 
to trace, either because it occurs in obviously recent plantations 
or because historical evidence of planting is _procurable. 
Whether indigenous or not, the beech grows well on all the 
Pennine slopes, both siliceous and calcareous. In favourable 
seasons, ripe fruits have been observed on trees at an altitude 
of 1500 feet (457 m.). First-year seedlings are frequently met 
with in the woods: older seedlings, however, have not been 
observed ; and there is no evidence to show that the beech 
rejuvenates itself in these hilly woods. Apparently the seed- 
lings of the beech are all destroyed during their first winter, 
perhaps because they are unable to endure the alternating cold 
and mild periods characteristic of the markedly insular climate 
of the north and west of the British Isles. On the other hand, 
the rejuvenation of the beech may be observed on sandy and 
on chalky soils in the south of England, where the tree is 
indigenous. The analogy of the beech to the pine in the 
matter of rejuvenation in the north and south of England is 
remarkable; and it may be that the pine, as well as the 
M. 4 
