FORESTS OF KOCKY MOUNTAINS FOREST RESERVE 43 



even when a fire runs through an area of reproduction. Most of the aspen, at 

 present, is second-growth and immature and trees over 8 inches in diameter and 50 

 feet in height are infrequent. It is very intolerant, more so than any species except 

 perhaps paper birch or alpine larch. It reproduces best on a freshly burned soil, which 

 should preferably be moist. It is the most aggressive species on the edge of grass- 

 land, but makes appreciable headway only when fire temporarily kills off the grass. 

 It is nearly always found as a fringe on the edge of meadows in second-growth 

 pine stands, where the moist seed-bed and its rapid seedling growth favoured it 

 rather than pine. Its ability to coppice, even when very young, gives it an advantage 

 over pine in struggle for the occupancy of areas subject to repeated fires. Repro- 

 duction only three feet high will, after being killed by fire, be followed by coppice 

 shoots from the stems and roots. The starting of coppice growth from the roots of 

 living- trees also gives aspen a chance that is not possesssed by other species to make 

 headway against grass. 



PAPER BIRCH. 



This is a very uncommon species in this region and was only once observed on 

 a snow-slide not far from timber-line in the region of the Bow river. 



METHOD OF STUDYING REPRODUCTION. 



The method of studying reproduction outside of the making of general obser- 

 vations was to count, on definite sample areas, the number of seedlings, which would 

 afford a basis for quantitative comparisons, and at the same time to make a com- 

 plete and careful description of the conditions of the area, emphasizing the points 

 of special influence. The description was made according to a schedule covering the 

 following points : elevation, slope, aspect and site quality, type and proportions of 

 different species, age, density and condition of stand, light admitted to plot, seed- 

 trees and cones, undergrowth, ground cover, humus and soil. The reproduction was 

 divided into three size-classes, viz., (1) up to 6 in., (2) 6 in. to 3 ft.. (3) 3 ft. to 10 ft. 

 Two kinds of sample areas were taken: first, to show optimum or extreme con- 

 ditions of any kind, plots 10 ft. square, in area approximately 1/400 acre; second, 

 to show average reproduction under certain widespread conditions such as those 

 resulting from a fire or lumbering, strips J or $ chain in width and up to J mile 

 in length. The small plots allow the making of very accurate and definite descrip- 

 tions of the factors influencing reproduction and are most useful when taken in 

 places where there is reproduction of from one to five years in age. Strips may be 

 taken in areas where the reproduction is any age below that at which seedlings 

 begin to die as a result of crowding, but are also most useful where the seedlings 

 are very young. 



