Clare Island Survey — Tree Growth. 



9 9 



Birch. These species, or one or the other of these species as the case 

 may be, extend about 100 yards in from the original edge of the bog, and 

 occasionally to a greater distance nearer the centre, but in the deeper parts of 

 the bog the only species found are Pine and Birch, except where eskers raise 

 the surface of the natural soil to about the level or horizon at which the 

 Oak occurs, when Oak or a mixture of Pine and Oak is usually found. 



Fig. 1. Typical section through small lowland bog. xx Pine stumps, oo. Oak stumps. 

 «, Sphagnum peat. b, Upper marsh peat. c, Lower marsh peat. 



Fig. 2. Typical section through mountain slope, showing marsh and mountain peat, xx Pine stumps. 



In bogs of not more than 100 acres or so in extent, the entire base of the 

 bog may be dotted over with tree-stumps, but the larger bogs show few, if 

 any, signs of stumps at a greater distance than 200 or 250 yards from the 

 edge, and many bog sections are quite free from stumps, although in very 

 few bogs as a whole are they entirely absent. Another feature of many 

 Irish bogs is the occurrence of root-layers through the body of the bog, and 

 at varying heights above the bog base. Near the margin of the bog, the 

 root-layer may consist of Oak or Pine, but rarely of Pine alone, but at 

 distances of 100 yards or more from the margin, and as the thickness of bog- 

 above the root-layer increases, Pine and Birch appear to be the only species 

 represented. The upper root-layer is invariably under the Sphagnum peat, 

 and usually on or near the surface of the black or marsh peat, but, beyond 

 a few small Birch, the writer has never seen a stump above this surface. 

 Another feature of this upper root-layer is its invariable occurrence at about 

 3 to 4 feet above the present water table, which, in most bogs, has been 

 lowered by artificial drainage by at least a couple of feet. 



R.I. A. PROC, VOL. XXXI. B 9 



