FORESTS OF ROCKY MOUNTAINS FOREST RESERVE 31 



tively light, and are easily distributed by the wind. Three hundred feet is about 

 the maximum distance for seed to be distributed and 150 feet the limit of effective 

 seeding on a favourable seed-bed. 



Development of Seedling. When the seeds germinate, about five to eight 

 cotyledons appear, followed by the first year's leaves, and at the end of the year the 

 seedling is one inch high with a root about three inches long. The seedling at first 

 grows very slowly, and at ten years is only a foot high. Moisture is necessary, and 

 that is the main factor governing the favourableness of various seed-beds. The 

 thickness and texture of the surface material are also important factors since they 

 influence the ease with which the roots can reach the soil and also the ease with 

 which the roots can avail themselves of the water present in the soil. 



In virgin spruce stands, reproduction is found mainly in openings, and is then 

 dependent on the humus being well decomposed and less than two inches thick, 

 and on the ground cover being thin and compact enough to allow the seedlings to 

 take root. The surface moisture is usually sufficient on account of both the shade 

 afforded by spruce stands and the moist soils usually associated with that type of 

 forest. The best reproduction was actually found on bare, very moist soil, in one 

 case produced by the grading of a road on a hillside and in another case by spring 

 floods washing out a steep creek-bank. The uprooting of trees also provides favour- 

 able spots for seeds to germinate. The next best seed-bed is that afforded by a 

 covering of compact, well decomposed humus up to one inch and a half thick, over 

 which lies a thin compact layer of moss or of litter composed of needles or twigs. 



The almost classical occurrence of spruce seedlings on rotten logs is quite 

 characteristic in this region, and is readily explained by the capacity of the decayed 

 wood for holding moisture and at the same time providing a medium firm enough for 

 the seedlings to take root in. 



In clumps of light-foliaged willow shrubs which usually grow on moist ground 

 where there is considerable grass, excellent spruce reproduction was often found. The 

 light shade of the shrubs checked the growth of the grass and the decayed leaves 

 beneath them formed an excellent seed-bed. 



The chief deterrents to reproduction are thick, dry litter, which may be found 

 in very dense young stands, or a thick, loose growth of sphagnum moss, which is 

 unfortunately the prevailing condition in spruce stands. The favourable conditions 

 above cited are found usually on only a small percentage of the total ground surface 

 of a virgin forest, and result in the presence of such a small amount of volunteer 

 growth that reproduction beginning after cutting operations must in most cases be 

 the main source of a new stand. In mixed stands, the humus is usually better 

 decomposed, and the quantity of moss in the ground cover is less than in pure spruce 

 type ; and thus often they show the densest and most uniform reproduction of 

 spruce. 



Fire is with spruce, the same as with pine, the instrument that most effectively 

 produces on a broad scale surface conditions favourable to reproduction. The most 

 important effect of fire, however, is on the supply of seed, and where that is destroyed 

 reproduction will be poor, even though the seed-bed conditions are satisfactory. 



Quantitative observations were made both of average and extreme conditions 

 under which reproduction took place and show the relative importance of several 

 factors entering into the problem. 



To illustrate the effect of distance from seed-trees on spruce reproduction in 

 burned-over areas, two strips were run from the edge of a green spruce stand into 

 an area where reproduction was taking place after a fire. The original stand had 

 considerable pine in its composition and the majority of the reproduction is of that 

 species. 



