follows: boron, 15 ppm: nitrogen, 1.50 percent; phos- 

 phorus. 0.40 percent; and sulfur, 2,402 ppm (Walker 

 and others 1955) (table 11). In the foliage of released 

 western redcedar, however, concentrations were found 

 to be low: boron, 11.8 ppm; nitrogen, 0.79 percent: 

 phosphorus, 0.1 1 percent; sulfur, 362 ppm. Also foliar 

 amounts of potassium and magnesium approached the 

 deficiency concentrations reported by Walker and 

 others (1955) for western redcedar. 



Discriminant analysis simultaneously detected 

 differences in the mean nutrient contents for 12 

 different nutrients in the foliage of released western 

 redcedar. Foliage with colors 5.0 GY 5/8. 7.5 GY 5/6. 

 and 7.5 GY 6/10 were individually unique in nutrient 

 content (table 12). Likewise, foliage with color 2.5 GY 

 5/6 had significantly different nutrient content than all 

 other colored foliage except foliage with color 2.5 GY 

 7/8. 



Discussion 



Western redcedar foliar characteristics were related to 

 the differences between released and predicted non- 

 released tree diameter growths. Amounts of foliar 

 manganese, iron, sodium, potassium, sulfur, and phos- 

 phorus were significantly (P^0.05) related to the dia- 

 meter growth response of western redcedar. 



The antagonistic effect of one plant nutrient to 

 another plant nutrient could explain some of the rela- 

 tionships between foliar nutrients and the response of 

 western redcedar to release. Foliar phosphorus had a 

 positive significant relationship with the release 

 response of western redcedar and also appeared to be 

 deficient when compared to the amounts reported by 

 Walker and others (1955). Magnesium can restrict the 

 uptake and accumulation of phosphorus by trees (Gysi 

 and others 1975). In contrast, in the data presented 

 here on the release of western redcedar, an interaction 

 between magnesium and phosphorus could not be de- 

 tected. Although an interaction could not be detected, 

 larger amounts of foliar magnesium could possibly 

 result in larger amounts of foliar phosphorus, which in 

 turn could result in greater diameter growth response 

 of western redcedar to release. 



The negative relationship of foliar potassium to the 

 release response of western redcedar from competition 

 could be caused by the deficient amount of nitrogen 

 found in the western redcedar foliage. Nitrogen is 

 known to interfere with the uptake and accumulation of 

 potassium in tree foliage (Brendenmuehl 1968; Benzian 

 and Freeman 1967). Therefore, the negative relation- 

 ship of potassium to release could actually be a 

 nitrogen deficiency expressed by potassium even 

 though an interaction between potassium and nitrogen 

 could not be detected. Perhaps no interaction was 

 detected because potassium is highly mobile within a 

 tree (Bukovac and Wittwer 1957); therefore, adequate 

 amounts for foliage metabolism can be supplied 

 through redistribution within the tree (Switzer and 

 Nelson 1972). 



The nitrogen deficiencies that appeared in the foliage 

 of released western redcedar could also cause the nega- 

 tive relationships of sodium and sulfer to the release 



responses of western redcedar. Concentrations of both 

 sulfur and sodium in the tree foliage can be affected by 

 concentrations of foliar nitrogen (Shoulders and McKee 

 1973). As with potassium no interaction between 

 nitrogen and sodium or sulfur could be detected. 



The color of western redcedar foliage after release 

 also reflects the amount of nutrients accumulated in 

 the foliage. Foliage with three different colors as 

 distinguished by Munsell Color Company (1952) 

 notation contained nutrient amounts which differed 

 from each other and from the foliage with eight other 

 colors. The relationships of foliar colors and amounts of 

 foliar nutrients to release could easily be altered by 

 release operations. Increased amounts of organic matter 

 in the form of leaves, branches, and boles of trees left 

 after a release cutting could easily change the uptake 

 and accumulation of nutrients. Nitrogen and other 

 nutrients can be tied up in the breakdown of organic 

 matter, making such nutrients unavailable for tree 

 growth. As little as 2 percent of total nitrogen can be 

 available for tree growth, with the remainder involved 

 in the breakdown of organic matter (Shoulders and 

 McKee 1973). In turn, the different amounts of 

 accumulated nutrients in the foliage of the released 

 western redcedar could alter foliage color. 



Western redcedar with the more yellow foliage 

 showed the best response to release. Such trees were 

 probably more open grown than others, which resulted 

 in both the better diameter growth and the more yellow 

 foliage. In contrast, the trees with the slower diameter 

 growth probably grew in the more dense portions of the 

 stands, which resulted in both the slower growth rates 

 and greener foliage. 



Foliar properties appear to be significantly related to 

 the differences between the diameter increment of 

 released western redcedar and the predicted diameter 

 increment of nonreleased western redcedar. Nutrient 

 needs and accumulation might deserve consideration 

 when preparing cutting prescriptions for stands of 

 western redcedar, and also when planning future 

 research into the response of western redcedar to 

 release. 



CONCLUSIONS 



The diameter increments of western redcedar 

 increase in response to release from overhead and 

 surrounding competition. Several site, stand, and tree 

 characteristics were significantly (P S 0.05) associated 

 with the differences between diameter increments of 

 released trees and predicted diameter increments of 

 nonreleased trees. 



Several site characteristics are important con- 

 siderations in developing treatment alternatives for re- 

 leasing western redcedar. Stands growing on the Thuja 

 plicata/Pachistima mrysinites habitat type had the 

 best response to release compared to trees growing on 

 other habitat types. Trees growing on steep north 

 slopes had greater growth after release compared to 

 trees growing on other slopes and aspects. Likewise, 

 trees growing on soils with larger amounts of nitrate, 

 ammonium, sulfate, and potassium had greater growth 



15 



