THE NEW FORESTRY. 1 71 



severe thinnings check increment in a marked degree in the 

 trees left Plate 13 shows this very plainly. It represents 

 a section of a larch tree, and is an example of all the trees 

 in part of a mixed wood that was severely thinned and from 

 which the underwood and the fences were removed when the 

 trees were taken into the park in the form of a clump. The 

 broad rings from the centre to the letter A show the rate of 

 increment while the trees were sheltered, and the rings above 

 the letter A show the decreased rate of increment ,after the 

 shelter was removed. This group was under the author's 

 observation for many years, both before and after the thinning. 

 The larches becoming stunted were felled, and the section 

 was then photographed. 



SECTION IV. PRUNING. 



The pruning of forest trees is not necessary, except in 

 mixtures of ill-matched species, in which the weaker subjects 

 have to be preserved at the stronger ones' expense, and such 

 mixtures are condemned, for these reasons, in another chapter. 



Pruning is only required in the case of park and orna- 

 mental trees from which limbs have to be removed because of 

 injury to them, or for some other reason. In pruning such 

 trees, projecting stumps should not be left The limb to be 

 removed should be cut back to the next main limb or growing 

 point, and whether that point be at another limb or at the main 

 trunk, the cut should not be made flush with the bark of either, 

 but at the swell or ring of bark which is usually found at the 

 junction of a limb with the limb from which it springs. This 

 leaves a slight knob, the cut is of less diameter, occlusion sets 

 in sooner, and the wound is soon healed. Wounds soon heal 

 up in growing trees, but much depends on their size and the 

 age of the tree. Decay sets in where limbs have been broken 

 off, and often extends several feet down the limb or bole, 

 reducing the value of the tree. Purchasers probe such 

 wounds with flexible steel probes to ascertain their extent. In 

 treating wounds caused by pruning, or .anything else, care 

 should be taken to seal them up with some kind of styptic, 

 like wood pitch, black varnish, or white lead. If pruning is 

 done in early winter, when the sap is down, wounds soon dry 

 and may be painted over or plugged to exclude air or water. 

 The margin of bark round the wound must not, however, be 

 touched by the paint, but just smoothed by the knife and so 

 left. A roll of new tissue soon begins to form round the edges 

 of the wound, which in time is quite covered over. 



