1903-1904-] Rarer Woodland Plants of Scotland. 81 



ities the once well-wooded character of the land has been 

 proved by the timber found buried and preserved among the 

 peat. 



The term " moor " is usually applied to land encrusted with 

 a layer of acid humus, strongly preservative or even anti- 

 septic in character, and as regards plant - food, lacking in 

 proteids. This humus is principally formed by the remains 

 of sphagnum, which, always elongating, is continually adding 

 to the thickness of the peat layer. " Heath," as usually 

 understood, indicates a drier condition of the peat than is 

 found in moors, the peat also consisting usually of a larger 

 proportion of woody remains, as the stems of Calluna, Erica 

 cinerea, and other ericaceous plants. Beyond this difference 

 in moisture, and therefore in the vegetation and its remains, 

 there is little difference between heath and moor, and not in- 

 frequently both states occur side by side. 



The change from moor or heath to forest is one that 

 requires the hand of man in most cases. As, however, the 

 change from forest to moor takes place naturally, so also may 

 the opposite occur, although less frequently. Different species 

 of Pinus possess different degrees of vigour when they are left 

 to themselves among the infertile soil of the peat-lands. For 

 instance, Pinus montana uncinata will thrive where the Scots 

 pine languishes. In a moor the chances of a start in life for 

 the young pines lie chiefly in the hillocks of Erica rather than 

 in the softer sphagnum portions. As the trees grow there 

 slowly accumulates upon the ground, previously wholly held 

 by Carex, Eriophorum, Sphagnum, Erica, and the like, a layer 

 of pine needles and other debris. Here and there the sphag- 

 num of the moor yet crops up, while the other plants dis- 

 appear from some portions, holding their ground in a few. 

 The forest d4bris forms an ideal rooting medium for its true 

 carpet plants. Continually renewed, it varies but little with 

 time. Worms being for the most part absent, there is little 

 or no intermixing of the surface with the subsoil. Here, too, 

 is found remarkable evenness of moisture and temperature 

 throughout the year. 



The history of the pine-forests dominates the history of their 

 plant carpets. The dwindling of our pine in Scotland, its 

 isolation in forests by intervening tracts of treeless ground 



VOL. V. F 



