January 22, 1915] 



SCIENCE 



121 



proofs and examples from the facts estab- 

 lished by the foresters, and the forest liter- 

 ature of to-day is still practically the only 

 one which contains striking examples of the 

 application of ecology to the solution of 

 practical problems. 



One discovery recently made at the "Wind 

 Eiver forest experiment station in Oregon 

 comes particularly to my mind. In north- 

 western Idaho where the western white pine 

 is at its optimum growth and is greatly in 

 demand by the lumberman, our former 

 method of cutting was to remove the main 

 stand and leave seed trees for the restock- 

 ing of the ground. In order to protect the 

 seed trees from windfall, they were left not 

 singly but in blocks, each covering several 

 acres. The trees left amounted often to 

 from 10 to 15 per cent, in volume of the 

 total stand, and since they could not be 

 utilized later they formed a fairly heavy 

 investment for reforesting the cut-over 

 land. A study of the effect of these blocks 

 of seed trees upon 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. Splendid 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 growth origi- 

 nates 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 seeds 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 discovered that 

 the seed of the western white pine retains 

 its vitality for years while lying in the duff 

 arid 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 invariably 

 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, 

 amabalis fir, western red cedar and hem- 

 lock. 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 com- 

 position of the forest is determined by the 

 seed stored in the leaf litter; and the ap- 

 pearance of seedling's first of one species 

 and then of another results simply from the 

 differences in the relative endurance of 

 seed of the different species that are lying 

 in the ground. Besides being of scientific 

 importance this discovery has also a great 

 practical significance. 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 



