i9io.] 



Coombe Plantation, Keswick. 



sample tree was a fair representative of larch grown at such 

 altitude with no shelter save a narroAv belt of other larch. 

 The total height reached was 23 ft. 8 in., and the girth breast- 

 height 21 J ins.; these dimensions, with a form factor of '49, 

 give a volume to 4 ins. diameter of 2*9 cubic ft. true measure- 

 ment, and such is about the average volume of larch at this 

 elevation. 



A glance at the height-growth curve will show how ex- 

 tremely slow the growth of this tree was up to the age of 

 about 30 years. The tree found great difficulty in getting a 

 start owing to exposure to wind, and when, finally, some 

 shelter was obtained from the other larch to windward, and 

 the tree began to forge ahead, the effort came too late in life 

 to carry the tree to a respectable height. 



Group F. — Elevation, 1,100 ft. This group was in a very 

 exposed position, and finally, in the storm of 1894, all the 

 trees were blown down. The figures to that date, however, 

 show clearly the effect of exposure to wind on the girth- 

 growth. It will be observed that the curve for the group (see 

 curves, p. 271) cuts across the curves for both the 1,1 150 -ft. 

 and 1,250 ft. groups. While the effect of exposure to wind on 

 height-growth is sufficiently obvious, one is apt to overlook 

 the resulting decrease in diameter. No sample tree was taken 

 to represent this group. 



Effect of Elevation on the Growth of Larch and 



Spruce. 



It will be seen from the curves that there is, except in the 

 height-growth curve for the tree at 1,000 ft. elevation, a 

 general falling off in both height and girth with increased 

 elevation. From the data obtained from the experimental 

 groups of larch and from measurements of trees in the 

 vicinity of each group, it has been found possible to construct 

 curves which show the relation of the average volume per 

 tree to the elevation (see curves, p. 272). 



Between the elevations of 1,250 ft. and 1,500 ft., where no 

 experimental groups were measured, the curves have been 

 constructed for larch and for spruce from the volumes of some 

 2,900 larch and 285 spruce felled in 1907-8, supplemented by 

 measurements of trees felled during the present year. 



It will be noticed that from 1,000 ft. to 1,250 ft. the larch 



