46 ANNALS OF SCOTTISH NATURAL HISTORY 



The marshy nature of the ground is only one of the 

 conditions which have prevented the moor from being natur- 

 ally replanted in course of time by the abundant source of 

 seeds in the old wood, with the prevalent westerly wind to 

 transport them. The stunted growth of the trees one of 

 which is seventeen years old and yet only 7 feet high and the 

 frequency of broken tops and branches testify to the severity 

 of climatic conditions. Sheep and rabbits nibble the young 

 leaves ; and every few years the heather is burnt by the 

 game-preserver. When all the causes tending towards ex- 

 termination are considered, it is surprising that even a few 

 examples have managed to survive. These favoured few 

 are mostly in spots which have escaped burning for a 

 number of years ; and the best grown specimens have been 

 sheltered during their earliest years by the long heather 

 around them. 



. Although 489 yards from the wood is the greatest dis- 

 tance at which any Birch trees were found, this is probably 

 considerably under the distance to which the seeds may be 

 carried. It might be suggested that a number expressing 

 more accurately the maximum distance of transportation 

 would be obtained by measuring the distances of seed-dis- 

 persal of those isolated young Birch trees which are common 

 on some Highland moors. 



The distance of 886 yards (Sio metres) here deter- 

 mined as within the possible range for the dispersal of Pine 

 seeds is very much greater than that of 1 1 5 metres given 

 by Fliche. In his paper he contrasts the smallness of the 

 distance to which Pine seeds are carried by the wind with 

 the greater distances to which animals carry the seed of 

 Beech (500-600 metres) and Rowan (1400-2100 metres); 

 but if this new estimate for the Pine is accepted, this contrast 

 can no longer be regarded as established. It is evident, 

 from the disparity which exists between the few definite 

 measurements yet published, that many more cases must 

 be recorded before we can reach any degree of accuracy on 

 the subject. 



