Dry Land Plants 227 



The grass suffers most destruction by eating, as can be 

 seen where portions of land have been enclosed within netting; 

 here grass rapidly springs up ousting the Carex. . In the open, 

 on the other hand, Carex, which is practically uneaten, drives 

 out the grass. Cladonia and Sedum acre are also untouched 

 and abound in places. 



When burrowing is carried out on a large scale by many 

 rabbits it produces what are practically deserts. The rabbits 

 bore into a gently sloping hill-side, the soil falls down, a 

 slight escarpment is made, and they bore again. This process, 

 continually repeated, gives rise to considerable extents of 

 loose sand, bounded on the upper side by a miniature cliff, 

 full of burrows, on the lower side merging almost imper- 

 ceptibly into the hill-side. The action of the wind upon the 

 loose sand is such as by purely mechanical means to prohibit 

 the growth of any vegetable life, but where stones offer any 

 protection against the moving grains Cladonia will often be 

 found. This may either cover in time the whole bare area or 

 give way to Festuca odna which in its turn gives way to 

 Carex. Towards the lower edge the Cladonia increases con- 

 siderably, with here and there a tuft of Festuca ovina and 

 the straight lines of Carex shoots, until the normal growth of 

 the undisturbed hill- side is reached. 



So far the effect of the rabbit upon the vegetation has 

 been principally destructive ; there is however one class of 

 plants the annuals which seem to depend for their very 

 existence upon the isolated earths dotted over the heath. 

 These heaps are at first bare, then when the hole is deserted, 

 or but little used, annuals spring up. The following have 

 been observed. 



Erodium cicutarium. 



Veronica arvensis. 



V. verna. 



Myosotis colllna. 



My. versicolor. 



Filago minima. 



Aira precox. 



152 



