8 BULLETIN 418, U. S. DEPARTMENT OF AGEICtJLTUEE. 



DEVELOPMENT OF SEEDLINGS. 



Although seedlings start with considerable vigor after each good 

 seed year, their mortality during the first year is exceedingly high. 

 In the early summer the forest floor is sometimes thickly dotted with 

 freshly sprouted seedlings, while on the same area the next year, as a 

 consequence of the summer drought and the winter ground heaving, 

 there will be but an occasional hving seedling. A count of the seed- 

 lings on 67 smaU sample plots distributed over five acres, in the fall 

 of 1910 (after the excellent seed crop of 1909 and the very dry season 

 of 1910), showed that 79 per cent of the seedlings which started that 

 spring had died by fall.^ Probably not one seed in ten escapes the 

 birds and rodents; and, of those that do germinate, probably as many 

 are killed by late frosts immediately after germinating or by frost- 

 heaving the first winter or by drought the first summer. It is esti- 

 mated that in eastern Oregon hardly more than one seedling in a 

 hundred lives to be 2 years old. After the first year the mortality 

 from drought is very shght. 



The year-old seedlings seem to do best beneath the partial shade 

 of the mother trees, probably because of the protection which they 

 are afforded against drying sun and winds, and perhaps against 

 frost as well. Older seedlings do not do well in dry places directly 

 beneath old trees, because of the absorption by the roots of the latter 

 of all the available soil moisture; the seedlings that ultimately suc- 

 ceed are those in the gaps between the clumps of old trees or beneath 

 those which have recently died. For some reason those in the latte'r 

 situation are particularly flourishing in eastern Oregon. On dry 

 soils, clumps of brush and mats of squaw-carpet {Ceanothus pros- 

 tratus) seem to assist yeUow-pine reproduction, probably by their 

 effect in conserving the soil moisture. 



For these reasons and for other causes which are not thoroughly 

 understood, yeUow-pine reproduction is extremely patchy in the 

 virgin forest; here there will be almost a thicket of young trees, and 

 near by, under seemingly similar conditions, there will be httle or no 

 reproduction. 



In dry situations bordering the limit of yeUow-pine growth, the 

 reproduction seems to be greatly benefited by the protection that 

 bushes afford, and it is conspicuously more abundant on the sheltered 

 north side of clumps of bushes than elsewhere. An examination ^ of 

 an area adjoining the desert in Crook County showed the following 

 interesting results: Of aU the yeUow-pine seedlings 70 per cent were 

 on the north side of sagebrush and bitterbrush bushes, 13 per cent 



1 Manuscript report, "Western Yellow Pine Reproduction," by George A. Bright, forest assistant. 



2 Manuscript report by Forest Supervisor M. L. Merritt, " Occurrence of Western Yellow Pine Seedlings 

 in Openings in the Edge of the Deschutes National Forest, Bordering on the Desert." 



