34 FORESTRY BRANCH BULLETIN NO. 33 



Pine prefers a dry to a wet soil, but, as in the mountains only the very bottoms 

 of stream and river valleys are very moist, there is only a very small area of soil 

 unfavourable to its growth. On the thin, rocky, dry soils of the upper slopes there 

 is a correspondingly small development of the individual trees and a large number 

 of trees per acre, and also an increasing liability to windfall. 



Although lodgepole pine is among the least tolerant trees of the region, its 

 intolerance is sometimes overestimated. Its shade-enduring ability is great enough 

 to allow over 200 trees 80 feet high on one acre to participate in the main crown 

 level at maturity. Among the pines it ranks near white pine in tolerance and is 

 much more tolerant than eastern jack pine, red pine or yellow pine. In this region 

 the trees less tolerant than the lodgepole pine are white-bark pine, Lyall's larch, 

 balsam poplar, aspen and paper birch. Compared to spruce, however, lodgepole pine 

 is very intolerant, and the form of the tree, with its clean, slightly tapering bole, 

 and short, small crown, bring this contrast out. Seedlings of lodgepole pine do not 

 develop with great readiness in virgin stands, although they will grow in openings 

 or in stands partially thinned out by ground fire. Young seedlings or trees have 

 considerable power of recovery of growth after suppression, though not as much as 

 spruce, and the larger trees, especially when grown in rather dense stands, show 

 very slight capacity for ( stimulated growth.' 



Pine is more susceptible to damage than spruce, not only from fires, but from 

 other agents as well. Insect damage seems to be limited, although occurrences of 

 Dendroctonus beetles have been noted. 



Fungus attack is common in some localities, although never on more than a 

 small proportion of the stand. The fungus turns the heart-wood reddish with white 

 flecks, and makes it soft and punky. This rot may occur at the butt or sometimes 

 only in an upper portion of the bole, so that the fungus probably gains entrance 

 through a wound on the trunk of the tree. Fruiting bodies of the fungus are uncom- 

 mon and the species was not determined. 



The most destructive influence in many places is the dwarf mistletoe (genus 

 Arceuthobium'). This is a small branched plant about 1 in. to 1J in. long with 

 minute leaves. It grows in colonies ,on the younger portions of the tree and causes 

 malformations known as ' witch's brooms.' Its more serious effect is the killing of 

 the growing layer of the wood; eventually an area of dead wood is thus left exposed, 

 and these areas are thought to be the main sources of entrance to the fungi. The 

 mistletoe directly deprives the tree of some of its nourishment, and with the aid of 

 the fungus may finally bring about the death of the tree. A mature pine stand was 

 found with 80 per cent of the trees dead, and mistletoe had contributed largely and 

 had probably, in nearly every case, been the initial factor in bringing about the 

 result. 



Widespread wind-fall of pine is uncommon, although on the higher slopes a con- 

 siderable- proportion of the stand may be thrown. 



A minor cause of damage is porcupines which eat off in patches the bark near 

 the base, or sometimes high up on the trunk, and where the area is extensive enough 

 to girdle the tree, the latter may be killed. 



In general, pine is here very sound, and few logs and small amounts of lumber 

 need to be culled for defect. 



Reproduction. 



Seed Production. The manner of seed production is one of the most important 

 of the individual characteristics of lodgepole pine. It is distinct, not only from the 

 other genera but also from other species of pine, except jack pine. The main points 

 of interest are: first, the early age at which seed production begins; second, the 

 quantity and comparative regularity of production ; third, the persistence of the cones 

 on the trees; fourth, the slow release of seeds from the cones, resulting in an almost 

 permanent locking up of a considerable proportion of the seed ; and finally, the long 

 retention of germinative capacity by the seed. 



