262 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1915. 



natural reforestation has proved that they can not be depended upon, 

 at least within a reasonable time, to restock naturally the cut-over 

 land. The distance to which the seed is scattered from these seed 

 trees is insignificant compared with the area to be reforested. Splen- 

 did young growth, however, is found here and there on cut-over 

 land, away from any seed trees, where the leaf litter is not completely 

 burned. It is evident, therefore, that the seed from which this 

 young gi'owth originates must have come from a source other than 

 the seed trees. The study of the leaf litter in a virgin stand showed 

 that the latter contained on the average from one to two germinable 

 seed per square foot. Some of the seed found was so discolored that 

 it must have been in the litter for a long time. Thus, it was dis- 

 covered that the seed of the western white pine retains its vitality 

 for years while lying in the duff and litter beneath the mature stands, 

 and then germinates when the ground is exposed to direct light by 

 cutting. It was found similarly that in old Douglas fir burns, where 

 the leaf litter was not completely destroyed, the young growth in- 

 variably sprung up from seed that had escaped fire and had been 

 lying dormant in the ground. Should a second fire go through the 

 young stand before it reaches the bearing stage, the land may become 

 a complete waste, at least for hundreds of years, although there may 

 be seed trees left on the ground. This conclusively proves that the 

 young growth comes from the seed stored in the ground before 

 cutting took place and not from the seed scattered after cutting by 

 the seed trees left. 



The wonderful capacity of the leaf litter and duff of the cool, dark 

 forests of the Northwest to act as a storage medium for the seed 

 until favorable conditions for its germination occur is confined not 

 only to the Douglas fir and western white pine but to the seed of 

 other species which often grow together with them, such as noble 

 fir, amabilis fir, western red cedar, and hemlock. The subsequent 

 appearance of other species in a Douglas fir or western white pine 

 stand depends apparently, to a large extent, upon the seed stored in 

 the ground at a time when the original forest still existed. This 

 discovery revolutionizes our conception of the succession of forest 

 stands, since it shows that the future composition of the forest is 

 determined by the seed stored in the leaf litter; and the appearance 

 of seedlings first of one species and then of another results simply 

 from the differences in the relative endurance of seed of the dif- 

 ferent species that are lying in the ground. Besides being of sci- 

 entific importance this discovery has also a great practical signifi- 

 cance. It accentuates the disastrous consequence of a second fire in 

 an old burn, because no more seed remains in the ground while the 

 capacity of the few seed trees that may be on the burn is very limited 

 in restocking the ground. This discovery enabled the Service to 



