SEED DISPERSAL OF PINUS SYLVESTR1S & BETULA ALBA 45 



Yards. 

 At 266. i Pine, top broken, circumference 8|- inches, still living. 



i Birch, height 10 feet, circumference 8 inches, in good 



condition, bearing staminate catkins. 

 ,,366. i Pine, height 3 feet, about ten years old. 

 489. i Pine. 



3 Birches, all in good condition. 

 ,,746. i Pine, dead, about seven years old, in damp soil amongst 



Erica Tetralix. 

 ,,771. i Pine, dead, about seven years old, in damp soil amongst 



Erica Tetralix. 



,, 837. i Pine, fourteen years old at least. 

 ,,878. i Pine, height 5 feet, circumference 9^ inches, in good 



condition. 

 ,, 886. i Pine, height 7 feet, circumference i6i inches, about 13 



years old, in good condition. 



5 Pines, in good condition ; these were not on the direct 

 line of measurement, but near the last -mentioned 

 example, and at much the same distance from the 

 wood. 



Beyond this point no trees were observed, the ground 

 being composed of loose dunes, and in other ways unsuitable 

 for the growth of trees. 



These observations show that Pine seeds have been 

 carried as far as 886 yards, and Birch seeds as far as 489 

 yards. 



It will be observed that the trees occasionally occur in 

 groups separated by long gaps. This is due to the nature 

 of the ground, which is in the form of alternating ridge and 

 hollow. The ridges are drier and more suitable for the 

 growth of trees than the marshy hollows. The dominant 

 vegetation on the ridges is usually Calluna vulgaris, while in 

 the hollows Erica Tetralix is the most abundant. All the 

 trees from i to 500 yards are associated with Callnna 

 vulgaris. From 500 to 800 yards the ground is occupied 

 by a broad marsh with Erica Tetralix^ and there only two 

 trees were found ; both were dead, probably having suc- 

 cumbed to the damp nature of their habitat, which may 

 perhaps have been drier while they lived. From 800 

 to 886 yards the association is again that of Calluna 

 vulgaris, although with some Erica Tetralix mixed ; and in 

 this part eight of the trees were found. 



