LIFE HISTORY OF LODGEPOLE PINE IN ROCKY MOUNTAINS. 11 



tive is very apt to be overestimated. One reason for this is that, 

 natural reproduction has often been credited to wind-sown seed, when 

 • in reality the seed was already present on the area in sealed cones. 

 Hodson, 1 as the result of a study on a large number of cut-over areas 

 in Montana and Wyoming, concludes that " the largest amount of 

 seed falls within a hundred feet of the seed tree, and the radius of 

 effective reproduction is much less than is commonly supposed." 

 Clements states that the distance to which seed is carried by the 

 wind "was never found to exceed 164 feet." Undoubtedly the dis- 

 tances seeds are carried varies considerably with the topography and 

 the situation of the seed trees. Trees on a ridge exposed to high winds 

 will distribute seed the maximum distance. Until more definite in- 

 formation is available, it is safe to assume that wind distribution 

 should not be relied upon for distances of more than 150 to 250 feet, 

 according to the character of the situation. 



REQUIREMENTS FOR NATURAL REPRODUCTION. 



Owing to its intolerance of overhead shade, lodgepole pine will not 

 reproduce satisfactorily without considerable direct light. Although 

 the seed will germinate with a vary small amount of light, the young 

 seedling soon dies without it. In mature stands a heavy thinning 

 which reduces the crown density to about one-half is usually neces- 

 sary to permit a fair amount of reproduction to start and thrive. 

 Where the stand is opened by the removal of groups of trees on areas 

 of 3 or 4 square rods or more, reproduction will usually start and 

 grow well in the openings. Reproduction starting in this manner is 

 more apt to be uneven aged and better divided into height classes, and 

 consequently in less danger of stagnation, than in the dense, even 

 aged stands of uniform height which so often follow fire. Vigorous 

 young growth has been observed under stands in which a heavy and 

 uniform thinning had been made, causing the forest to resemble one 

 undergoing regeneration by the shelterwood method. In stands of 

 only moderate density, however, seedlings are apt to be spindling and 

 slow of growth. 



The most favorable seed bed for germination of lodgepole pine 

 seed is a mineral soil with plenty of available heat and moisture. 

 Needles and undecayed humus are apt to dry out rapidly in the 

 spring, before the rootlets of most of the seedlings can reach the 

 mineral soil. That mineral soil is not always necessary for germina- 

 tion, however, is shown by the fact that on old cuttings in Montana 

 where there has been no fire, seedlings apparently start indiscrim- 

 inately on patches of mineral soil and in small clumps of pine grass 



1 Silvical Notes on Lodgepole Pine, by E. R. Hodson, in Vol. Ill, No. 1, of the Proceed- 

 ings of the Society of American Foresters. 



