34 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 



I 



surrounding mountains. Dense timber frames the swamps and ex- 

 tends up the slopes to the mountain tops. The elevation of all three 

 tracts varies from 4,150 to about 4,400 feet. Low winter tempera- 

 tures and severe lightning storms are frequent in the entire region. 

 Two of the tracts, the Pelican Bay Lumber Co. sales area and the 

 Odessa ranger-station tract, are situated on the west shore of the lake. 

 They are about 2 miles apart and present conditions so much the same 

 that they can be considered as one. 



The Pelican Bay tract on the west side of Pelican Bay lies, as far as 

 the area covered by this study is concerned, along the slopes; the 

 aspect is east to northeast. That is, it is exposed to cold wintry 

 winds, sweeping unbroken across Upper Klamath Lake. We may 

 expect frost injury. The volcanic soil is fairly deep and loose; the 

 humus layer is rather shallow. There are no rock outcrops. The 

 underbrush is composed of Ceanothus, manzanita, and some chin- 

 quapin. 



The Odessa ranger-station tract is far less steep than the Pelican 

 Bay tract. A considerable part of it is a gentle slope, almost level. 

 The general aspect is north; presumably the tract is less exposed to 

 sweeping winds of very low temperature. The soil is decomposed 

 lava, but richer in humus than the Pelican Bay tract. Outcrops of 

 rock are frequent. There are a number of large springs in the neigh- 

 borhood. The underbrush is rather dense and is composed of 

 Amelanchier alnifolia, Ceanothus velutinus, with some Salix sp.; the 

 ground cover consists of Ceanothus prostratus, Berberis aquifolium, 

 and Symphoricarpus racemosa. 



The third tract, the Otter & Burns sales area, lies about 15 miles 

 north of the north end of Upper Klamath Lake. The tract is level, 

 the soil very loose, sandy, decomposed pumice, with no indication of 

 rock. Under the influence of the Fort Klamath Valley with its 

 swamps, the atmospheric humidity is rather high, as is evidenced by 

 the rich lichen flora, Alectoria fremontii being common. Thus the 

 immediate surface of the soil is kept damp, and litter disintegrates 

 very rapidly. The humus is about 1 to 2 inches deep; the soil imme- 

 diately underlying it is remarkably well drained. The rapid humifi- 

 cation in the top layers favors the development of mycorrhiza on the 

 roots of white fir in surface strata. White fir seedlings show a thick 

 matting of mycorrhiza, confined to the same strata of a certain humi- 

 fication, and a very long taproot seeking water. Yellow-pine seed- 

 lings also develop a taproot, but the mycorrhiza rootlets are found 

 at a greater depth than those of white fir. They are not as closely 

 bunched as in white fir and are distributed over a larger area in a 

 vertical direction. The underbrush is formed by Ceanothus velutinus 

 of medium density, from 4 to 6 feet high, in a uniform cover. 



