730 JOURNAL OF FORESTRY 



B. Height 



Species In bogs Outside in'^bog^' 

 cm. cm. 



Western hemlock 7-37 •• 1707 43-1 



Western white pine 5-39 •• 8-62 62.5 



Giant cedar 6.45 •• 18.55 34-7 



Douglas fir 6.32 .. 20.93 33- 1 



The averages in B are figured from the data for all the trees repre- 

 sented whose height had been noted, except in the case of lodgepole 

 pine, which has been omitted, since the height of only one tree in a bog 

 had been recorded. The per cent for each species in the last column is 

 obtained by dividing the number in the first column by the correspond- 

 ing number in the second column, and therefore represents, on a per- 

 centage basis, the amount of growth in the bog as compared with the 

 growth outside. 



The quotient obtained by dividing the total diameter of all individual 

 trees reported in bogs by their total age is 0.83, while the quotient thus 

 obtained for all trees reported outside of bogs is 1.30. It thus appears 

 that, computing by individuals (not by species), the average rate of 

 growth in diameter of all trees reported in bogs is 63 per cent of the 

 average growth in diameter of all trees reported outside of bogs. 



Figuring in the same way, it is found that the average annual growth 

 in height of all individuals reported in bogs is 6.26 cm., while the aver- 

 age for all individuals outside of bogs is 16.47 cm. For the individuals 

 reported the growth in height in bogs was 37 per cent of the growth 

 outside. 



This should mean that the trunks of trees in bogs should show a 

 more decidedly conical shape than trees outside. This conclusion was 

 checked by observing a number of individuals in both habitats and was 

 found to be correct. 



The western hemlock is the commonest tree in Puget Sound bogs. 

 In so far as the above data can be taken as representative of the region, 

 it grows in diameter more rapidly in bogs than any other species, and 

 also the ratio of its rate of growth in bogs to its rate of growth outside 

 is greater. It also excels all other species in absolute growth in height 

 in bogs. If we consider the ratio of the rate of growth in height in 

 bogs to the rate of growth in height outside of bogs, it is surpassed by 

 the western white pine only. The western hemlock thus seems to be 

 by far the most successful invader of Puget Sound bogs. It is found 

 in every bog examined in the region that is far enough advanced to 

 have trees in it at all, while the western white pine occurs in only one 



