20 CLIMATIC CYCLES AND TREE-GROWTH 



deep into the trunk, the strain on the remaining wood is tremendous 

 and it cracks badly in lines parallel to the saw. If its own weight does 

 not keep it from binding the saw, steel wedges are driven in the cut 

 to force the tree up on that side. The tree usually begins to fall 

 some time before it is completely cut from the stump, the portion that 

 is uncut breaking off at the level of the undercut. The stump then 

 shows the sawed surface for two-thirds of the diameter on one side, 

 the chopped surface of the undercut a foot or two lower on the other 

 side (in the big trees), and between these a broken and splintered 

 space where the wood broke in falling. Sometimes the tree does not 

 fall of itself when the saw is approaching the undercut, and then 

 instead of sawing it completely in two, which would be dangerous, 

 sticks of dynamite are placed in the remaining attached portion and 

 the tree blown loose. This is apt to blow the stump to pieces, as 

 happened with D-18 of the early sequoia group. That sample was 

 therefore cut from the end of a log which had been 50 feet or so above 

 the ground. So nearly all stumps have a flat top, which will exhibit 

 from a little over one-half the diameter to more than three-quarters. 

 This restricts the choice of radius a little, but reduces the amount of 

 sawing in making the cuts for the radial piece. 



Selection of radius — In visiting a cut-over area with multitudes 

 of stumps, the first consideration is the apparent excellence of the 

 rings and the ease of cutting a radius which contains good readable 

 ones. In the Arizona pines this gives very little trouble. In these 

 trees the radius chosen and marked merely fulfills consistency regard- 

 ing points of the compass and contour of ground, and avoids fire-scars, 

 lobes, and knots in the stump-top itself. The piece cut out very often 

 takes the whole diameter. In the sequoias perhaps only 10 per cent are 

 without defects, and the inspection of stump-tops becomes an impor- 

 tant matter requiring from half a day to a couple of days. Deep fire 

 wounds in healing often inclose large masses of bark, and frequently 

 such scars have a considerable area of sapwood which has never 

 turned to heartwood. Such defects are always interesting for the 

 history they tell and are easily avoided in picking a radius. This 

 appears in the photograph of sequoia D-12 in Plate 1. 



One of the greatest difficulties with small fire-scars is the extensive 

 break they sometimes cause in the continuity of the rings. The fire 

 so alters the growing layer that for some distance away from the burnt 

 area the wood will crack and it may be very hard to say whether the 

 crack is within one annual ring or between two. Lumbermen say 

 that this cracking or checking takes place in the living tree. It is 

 attributed sometimes to temperature changes — frosts in the weakened 

 wood — and sometimes to wind. At any rate, in a weathered stump 

 such a crack becomes worse and makes it difficult to use otherwise 

 good material. In such cases it is always best to cut a separate small 



