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FORESTRY BRANCH BULLETIN NO. 33 



supply of seed that was left after the first fire, since usually a complete destruction 

 of the reproduction is caused by the second fire. Cones may remain which were not 

 opened by the first fire and have been lying on the ground keeping seeds enclosed 

 in a germinable condition. The second fire opens these cones and, although the first 

 reproduction is killed, it is followed by a satisfactory stock of seedlings. In fact, 

 in some cases, the area has been overstocked with seedlings after the first fire and 

 the reproduction following the second fire is of more advantageous density. In the 

 Crowsnest Valley, a fire occurred fifteen years ago and was followed by one nine 

 years later; and the reproduction after the second fire was of just about the right 

 density. 



MINOR DAMAGES. 



FROST. 



All the species in this region are very hardy, so that direct frost damage is 

 extremely limited. Poplar reproduction was found to be killed by frost in some 

 places. The Chinooks, however, increase the danger from frost, by causing very 

 rapid fluctuations in temperature, which may cause damage to even hardy adult 

 trees. No instances of extensive damage in the Canadian Rockies are at hand. In 

 Montana, near the continental divide, lodgepole pine had the leaves and, in some 

 cases, the buds killed. In the latter instance, the tree eventually died as no new 

 foliage could develop. This occurred during a period of very warm Chinook winds, 

 alternating with severe cold. The affected trees were confined to marked horizontal 

 belts, and on account of the reddening of the dead leaves, the name ' red-belt disease ' 

 was applied. 



SNOW. 



The most extensive damage done by snow is in snow-slides. These occur on 

 practically all mountains rising over 1,000 feet above timber-line which have steep 

 wooded slopes below. The slides are usually recurrent, and follow definite paths, 

 being guided by small gullies and clearing a strip on each side of the gully so that 

 an area of 100 feet wide is laid bare. The slides appear to start generally in a basin 

 on the bare mountain side where the snow can collect and where the sun can shine 

 with full strength and start the snow melting. The areas swept over by the snow 

 have a characteristic appearance, with the trees broken off at varying heights up to 

 fifteen feet, or uprooted entirely, and lying in parallel positions with their tops point- 

 ing down hill. Reproduction usually occupies the area, as the seed supply is good from 

 the adjacent stands. The ages and distribution of the young trees is irregular, 

 especially where the slides have been recurrent. 



Snow-slides have a practical bearing on the management of many stands, since 

 the danger from them will, in many cases, predicate very conservative cutting. 

 Opening up the stand too much and allowing the sunlight in too strongly might 

 start slides in new places, or allow the present courses of slides to be extended much 

 further down the slopes. Where a strip system of cutting is being followed danger 

 from snow-slides should influence the direction in which strips are laid out. 



GRAZING. 



The damage due to grazing is at present rather limited. Grazing is done on two 

 types of land in the mountains; first, on areas in the foot-hills, which are partially 

 stocked with young tree growth, usually of aspen and pine mixed, with some willow 

 shrubs; second, on meadows, usually entirely given over to grass, in the main valleys 

 farther up in the mountains. Grazing does practical damage mainly on the first 



