96 Journal of Agricultural Research voi. m. no. j 



part of the herbage on the lower, sparsely timbered lands are big bunch- 

 grass (Agropyron spicahim), little bluegrass (Poa sandhergii), big blue- 

 grass {Poa scabrella), and blue bunch-grass (Festuca arizonica). Ger- 

 mination and growth begin in the most exposed situations during the 

 first week in April, and early in May the vegetation shows everywhere 

 throughout the zone. Stock are usually not admitted before May 15. 



Canadian Zone. — The Canadian zone is characterized by lodgepole 

 pine {Pinus murrayana), the predominant tree of the region. In many 

 places the timber is so dense that there is little or no undergrowth of 

 vegetation. Only the most tolerant shrubs and herbs can exist in the 

 subdued light under the heavy timber, and such lands are of practically 

 no value for grazing. In other places extensive areas of lodgepole pine 

 have been burned over. Sometimes reproduction is established promptly, 

 but where fire has consumed most of the organic matter in the soil, the 

 reestablishment of vegetation of any kind is slow. Among the forerun- 

 ners in the invasion of permanent species, fireweed {Chamaenerion angustv- 

 /ol-inm), a valuable sheep forage, and pearly everlasting (Anaphalis 

 margaritacea) , a plant of no forage value, are most common. Both 

 growth and grazing begin in this zone fully 20 days later and end two 

 weeks earUer thaii in the Transition zone below. 



HuDSONiAN Zone. — The Hudsonian zone, in contrast with the lands 

 immediately below it, is open in character, the timber growing sparingly 

 and in clumps. The predominating vegetation consists of grasses inter- 

 mixed with various other palatable plants, as shown in Plate XIII, figures 

 2 and 3. 



This zone probably covers a larger area than the two lower zones com- 

 bined and supports most of the sheep permitted in the Wallowa Forest 

 during the summer growing season. On account of the demands made 

 upon this desirable range and because of the character of the forage, the 

 Hudsonian zone has suffered more serious depletion than any other, and 

 it was here that the most intensive study of revegetation was made. 



The trees of the Hudzonian zone, most of which extend to the nonnal 

 timber line, are Alpine fir {Abies lasiocarpa), whitebark pine {Pinus albi- 

 caulis), Engelmann spruce {Picea engelmanni) , and mountain hemlock 

 {Tsuga mertensiana). Whitebark pine is the most characteristic species, 

 and its altitudinal distribution is so clearly marked that one can be cer- 

 tain wherever it is met that the conditions there are those of the Hud- 

 sonian zone. The timber grows in small, dense clumps, precluding 

 an undergrowth of any but the most tolerant species. 



Aside from the timber, vegetation is distinctly herbaceous and consists 

 mainly of grasses and nongrasslike plants, commonly termed weeds. 

 While a great many of the species are grazed to a limited extent at one 

 time or another during the season, about 40 furnish 90 per cent of the 



