1910.] Coombe Plantation, Keswick. 275 



obtained were then used in rinding the volume of the trees 

 of the group and of the whole area. The breadth of the rings 

 was also measured on each section of three of the trees in 

 order to find the volume (without bark) at different periods, 

 and thus to calculate the periodic increment. The data 

 obtained in this way have been tabulated in Tables I. and II. 

 (at end). 



Some nine or ten groups of five trees each were in this 

 way established at various elevations, and of these the fol- 

 lowing have been chosen for description as the most 

 interesting : — 



Group A. — At 900 ft. elevation; number of trees, 4. The 

 aspect is east, the soil deep, moist and well-drained, and the 

 group is generally well sheltered. Two of these trees were 

 on the margin of the wood, and had received more than a 

 fair share of light. A reference to the height-growth and 

 girth curves will show that these are the most favourable 

 conditions for the growth of larch. The sample tree felled 

 reached a total height of 78 ft., and a girth of 45 ins. at 

 breast-height. The form factor was '440. The average 

 volume of the group was 54*0 cubic ft. (true volume), or 

 40*5 cubic ft. quarter-girth. 



The trees at this elevation are still continuing to grow 

 vigorously, as is shown by the leading shoots of 8 ins. for 

 both 1908 and 1907, and the height may be expected to 

 increase to about 81 ft. at the age of 70. 



Analysis of the sample stem showed that the increment 

 for the last five years was 2*3 per cent, per annum, and 

 for the preceding periods of five years 2*4 per cent., 3*81 per 

 cent., 4'i per cent., and 4*65 per cent, respectively. The 

 volume increment, therefore, first began to fall below 3 per 

 cent, at about the age of 55 years. The low rate of growth 

 during the last five years has probably been affected by the 

 successive defoliations by the Large Larch Saw-fly. 



Group B. — At 1,000 ft. elevation; number of trees, 5. 

 The aspect is south, the soil about 9 ins. deep and fairly 

 moist, the slope gentle, and the locality moderately sheltered 

 by other larch. The sample tree felled was not a particularly 

 good example of the group, which borders on the edge of the 

 wood and on a road, and has therefore received an inordinate 



