PERIODICAL LITERATURE 1047 



over a period of five years, from 1912 to 1916, inclusive. Eighty acres 

 were intensively examined by the transect and plot methods, and surveys 

 were made of 750,000 acres of burned and 7,780 acres of cut-over land. 



On the Columbia burn of 1902 the dufif was only partially destroyed 

 by fire. Excellent coniferous reproduction almost immediately covered 

 the area and was of the same species as made up the burned forest. A 

 careful analysis of the reproduction, its age and distribution, led the 

 author to the conclusion that the duff is the principal factor in repro- 

 duction in the Northwest after denudation. Where the duff is not 

 completely destroyed by fire the seeds therein which escape injury are 

 responsible for the reproduction, and not the seed trees on and adjacent 

 to the area. 



The investigation established the fact that the reproduction on the 

 burn occurred in variously sized patches irregular in outline, forming 

 a mosaic with patches of grass and other herbaceous vegetation con- 

 forming to the irregular burning of the duff, the reproduction occurring 

 on the unburned duff. 



A burn of 1910 on the upper Cispus River completely destroyed the 

 duff. The reproduction on this burn is reported by the author as only 

 in the immediate vicinity of seed trees. His conclusion is, when the 

 duff is completely burned the reprodviction which follows is in inverse 

 numerical proportion to the distance from the seed trees. 



Studies made on areas burned at intervals since 1864 led the author 

 to conclude that the seed of the whitebark pine may, under favorable 

 conditions, remain in the duff for 21 years without germinating — pos- 

 sibly through two or more fires — and still retain its viability. Although 

 some dormant seed may survive repeated fires, it was found that while 

 the reproduction is abundant and well distributed after a single fire if 

 the duff is not completely burned, it is extremely scanty and irregularly 

 distributed after a second fire. 



Many analyses of the duff from various types of forest in the North- 

 west and from recently denuded areas revealed from half to two 

 coniferous seeds per square foot of soil. Unfortunately the author 

 gives no tables of germination of the seeds of the various species sepa- 

 rated from the duff. The western white pine seed recovered from the 

 duff in northern Idaho were, however, germinated bv Brewster. He 

 secured a germination of from 2 to 20 per cent. 



The author discusses the dormancy habits of the seed of different 

 species and restates the well-known fact that in nursery and field 

 practice the best germination is often attained two or three years after 

 seeding. He concludes from the comparison of the year of the fire 



