i io MOUNTAIN AND MOORLAND 



We cannot leave the moorland without two notes. 

 First, we have only nibbled at it. Just as there are 

 different kinds of heath so there are different kinds of 

 moors. And in an upland moor it is often possible 

 to distinguish different zones, each with its own char- 

 acter. Thus botanists distinguish (i) the Bog Moss 

 association, (2) the Cotton Grass association, (3) the 

 association marked by a characteristic Sedge, called 

 Scirpus c&spitosus, (4) the Bilberry association, and 

 (5) the Heather moor. The arrangement of these 

 indicates a gradually decreasing amount of soil-water. 



The important general idea that we have tried to 

 make clear is this : that in a considerable variety of 

 habitats, which may be called moorland, there is sour 

 soil, abundant in humus acids, poor in usable nitro- 

 genous compounds, apt to be wet, cold, and badlv 

 aerated. The practical result is that though water 

 may be abundant it is not abundantly available. The 

 particular fitness to meet this is to economise trans- 

 piration, and there are many different ways of effect- 

 ing this. In his " (Ecology of Plants" (1909), Pro- 

 fessor Warming mentions, for instance, a well- 

 developed coating of hairs, as in some Willows, waxy 

 incrustations, as in Cranberry, thick cuticle, as in 

 Scirpus caspitoJus, thick skin, as in Cowberry, the 

 shutting in of the stomata so that the water vapour 

 escapes with difficulty, as in Ling and Bell Heather, 

 the reduction of leaves, as in Rushes, and sword-like 

 leaves, as in Iris and Bog Asphodel. 



Second, none of the types of vegetation is 

 permanent; all are in process of transition. In many 

 cases, the stumps of trees among the peat show that 

 what is now a peat bog was once a forest. In many 



