FOREST PATHOLOGY IN FOREST REGULATION. 35 



On the two tracts near the lake white fir is mixed with yellow pine 

 and Douglas fir, a little incense cedar, and a very little sugar pine. 

 On the Otter & Burns tract the stand is composed of yellow pine 

 and white fir, with occasional lodgepole pine. 



On each tract conditions were more or less uniform, differences in 

 elevation were negligible, and neither deep gulches nor steep slopes 

 had to be figured with as disturbing factors. All in all, 160 trees were 

 dissected and notes taken on all factors which possibly would have 

 some bearing on the subject of this bulletin. In operating, the tracts 

 were not clean cut; that is, not every white-fir tree in the area was 

 felled and examined, since it was not the object of the study to estab- 

 lish a cull per cent for that particular region. 



The data obtained are from selected trees. On the Pelican Bay 

 Lumber Company's sales areas the trees, of course, had all been 

 marked by the Forest Service officers in charge; on the Otter & 

 Burns sales area some trees were marked, and others were felled inde- 

 pendently of marking. On the Odessa ranger-station tract all trees 

 examined were felled for our special purpose. The representation of 

 trees of different ages, diameter, and height classes on the three tracts, 

 therefore, is not expressed correctly by the number of trees examined 

 on each tract. 



LOCAL PATHOLOGY OF WHITE FIR. 



The pathology of white fir in the Upper Klamath Lake region is 

 comparatively simple. Of injurious factors of an inanimate nature, 

 fire, lightning, and frost are common. 



Very few species of fungi inhabiting living white fir are found on 

 the three tracts. As we are mainly interested in the pathology of the 

 the wood, the occasional occurrence of Peridermium elatinum and of 

 LopJiodermium nervisequium becomes an entirely negligible factor. 



Of heartwood-destroying fungi in living white fir, EcJiinodontium 

 tinctorium is by far the most common, and sporophores are numerous. 

 About 75 per cent of all cases of decay were due to this fungus. 

 Occasionally decay may with some certainty be traced to Fomes 

 pinicola. In one case a sporophore of an Irpex was found in the 

 decayed hollow of the trunk. Trametes pini is missing altogether, 

 though found occasionally on neighboring sugar pine. Decay caused 

 by Polyporus schweinitzii was found in several cases, never with 

 sporophores. 



In other cases the decay was too indefinite to allow an identification 

 of the fungus causing it. This is particularly true for the many cases 

 of localized advance rot connected with scars from diffused lightning. 



The preponderance of EcJiinodontium tinctorium, especially in con- 

 nection with really damaging decay, is so marked that in this study 

 all important cases of decay are considered to be caused by this 

 fungus. 



