THE AUTHOR 



CONTENTS 



RUSSELL T. GRAHAM is a research forester working in 

 the silviculture of the cedar, hemlock, grand fir eco- 

 systems project at the Forestry Sciences Laboratory, 

 Moscow, Idaho. He began his career with the USDA 

 Forest Service in 1973 as a forester on the Bitterroot 

 National Forest and joined the Intermountain Station in 

 1975. He received his B.S. in forestry from the University 

 of Montana and his M.S. and Ph.D. in forestry from the 

 University of Idaho. 



RESEARCH SUMMARY 



Western redcedar is one of the most important 

 commercial species in the Northern Rocky Mountains. 

 The species usually responds well to release, but the 

 response often varies tremendously, depending on site 

 and tree characteristics. Therefore, this study was 

 implemented to identify the site, stand, and tree 

 characteristics associated with the release response of 

 western redcedar. Because no untreated stands were 

 available to compare to the treated stands, a diameter 

 increment model was developed and used in the analysis. 



Western redcedar appeared to best respond to release 

 from overhead and surrounding competition on northerly 

 aspects. In contrast, the poorest response to release 

 occurred on southerly aspects. After release the species 

 showed the best growth in the Thuja plicata/Pachistima 

 myrsinites habitat type and the poorest growth on the 

 Tsuga heterophylla/Pachistima myrsinites habitat type. 



The larger the tree was at the time of release the better 

 it responded to release. In contrast, the older the tree was 

 at the time of release the poorer the response it had to 

 the treatment. 



Soil characteristics were also associated with the 

 release response of western redcedar. Trees growing on 

 soils with high pH's showed the poorest responses to 

 release. Also, trees growing on soils with large amounts 

 of total nitrogen, iron, and copper showed poorer re- 

 sponses to release, whereas soils with larger amounts of 

 nitrate, ammonium, sulfate, and potassium supported the 

 trees that showed the better growth rates after release. 



In addition, foliage characteristics of western redcedar 

 were associated with the diameter increment response of 

 the species to release. Trees with the larger amounts of 

 foliar phosphorus and manganese had better growth rates 

 after release than trees with smaller amounts of these 

 nutrients. Trees with larger amounts of foliar sulfur, iron, 

 sodium, and potassium had poorer growth rates after 

 release compared to trees with smaller amounts of these 

 nutrients. 



Foliage color was related to the response of western 

 redcedar to release. Trees with green-yellow colored 

 foliage showed a better response to release than trees 

 with greenish green-yellow foliage. Also, foliage color 

 indicated the nutrient content of the foliage; mean 

 nutrient content differed among 12 different colors. 



The results of this study show that western redcedar 

 will respond favorably to release from overhead and sur- 

 rounding competition. The site and tree characteristics 

 that are related to the release response may be used to 

 help design treatment alternatives for releasing stands of 

 western redcedar. 



Page 



Introduction 1 



The Site, Stand, and Tree Characteristics 

 Associated with the Release Response of 



Western Redcedar 2 



Literature Review 2 



Methods 2 



Data Collection 2 



Data Preparation 3 



Prediction of Nonreleased Diameter Growth 4 



Identifying Significant Associations 5 



Results 6 



Zero to Five Years After Release 6 



Five to Ten Years After Release 6 



Ten to Fifteen Years After Release 6 



1975-1979 Period Qf Growth 6 



All Growth Periods 8 



Discussion 8 



Soil Characteristics Associated 

 with the Release Response of 



Western Redcedar 9 



Literature Review 9 



Methods 9 



Data Collection 9 



Identifying Significant Associations 10 



Results 10 



Discussion 10 



Tree Foliage Characteristics 

 Associated with the Release of 



Western Redcedar 12 



Literature Review 12 



Methods 12 



Data Collection 12 



Identifying Significant Associations 12 



Results 12 



Discussion 15 



Conclusions 15 



Publications Cited 16 



The use of trade names is for the information and 

 convenience of the reader and does not constitute an 

 official endorsement or approval by the U.S. Department 

 of Agriculture of any product to the exclusion of others 

 that may be suitable. 



Approved for publication by Intermountain Station 

 January 1982 



