Rabbits and Tree Seedlings 169 



their replacement by light-seeded ones which succeed on 

 the same type of soil. 



In many cases, also, the abundance of rabbits on the 

 light chalk soil must tell more heavily against the species 

 which produces fewer and less widely distributed seedlings 

 of slower growth. The destructive effect of rabbits is 

 sometimes extreme, as may be well observed on many 

 chalk downs, where the trees and bushes are uniformly 

 eaten close, up to a height that a rabbit can reach, while 

 no tree seedling and scarcely a herbaceous plant can 

 escape destruction, except the perennial constituents of the 

 turf, which are nibbled close to the soil (Plate XVIIIb). 

 No woodland has the slightest chance of regenerating itself 

 under such conditions, but where the incidence of this 

 factor is rather less severe the chances will probably be 

 in favour of the ash as opposed to the beech. The more 

 abundant and lighter seeds of the ash ^Yill produce a 

 more numerous and widespread crop of seedlings than 

 those of the beech, which will largely germinate where 

 they fall, under the edges of the tree canopy. In this 

 position, where the ground is relatively bare OAving to 

 the deep shade of the parent tree, they will easily be 

 seen by rabbits. The ash seedlings, on the other hand, 

 are carried far and vride and frequently germinate in 

 scrub or among tall grass, etc., where their earlier life is 

 to some extent protected. 



Thus with a disturbance of primitive conditions a 

 number of factors are seen to tell against the heavy- 

 seeded tree, in spite of its primary advantage of being 

 able to bear shade, to which no doubt it owed its original 

 success. 



Yeu--iDOods. The yew (Taxus haccata), as already 

 mentioned, is often abundant in beechwoods, where it 

 grows entirely shaded by the beech canopy; it is also 

 found very commonly in the chalk scrub, and sometimes 

 isolated yew shrubs occur in the chalk pasture, where 



