the growth of other species (Stage 1973; Stage 1976) as 

 well as to release response of other species (Ferguson 

 and Adams 1979). 



Stand density after release was related to the amount 

 of diameter growth western redcedar achieves. Western 

 redcedar stands with high CCF's after release had 

 growth rates less than western redcedar stands with 

 low CCF's. Increases in stand density after release can 

 be partially attributed to additional tree growth in 

 response to the treatment and to new regeneration. 



The stresses in western redcedar as it adjusts to a 

 new microclimate after a release cutting could make it 

 more susceptible to attack by Armillaria mellea (Vahl. 

 ex Fr.). Armillaria mellea is capable of spreading by 

 both root-to-root contact and by rhizomorphs infecting 

 other stump and tree root systems (Boyce 1961; 

 Morrison and Johnson 1978). Frequency of such con- 

 tact is increased in response to release; i.e., western 

 redcedar's extensive grafted root system expands along 

 with the expansion of ingrowth root systems. This 

 helps facilitate the spread of A. mellea throughout the 

 released stand. The mechanical operations of a release 

 treatment can increase the infection rate of Fomes 

 annosus (Fr.) Karst. and Heterobasidion annosum (Fr.) 

 Bref. in stands of western hemlock ( Wallis and Morrison 

 1975; Chavez and others 1980), but there is no evi- 

 dence that mechanical damage increases the infection 

 rate of A. mellea in released stands. Increasing tree 

 spacing by release cuttings does not prevent the attack 

 of western recedar by A. mellea, but it can actually 

 increase disease infection rates. 



SOIL CHARACTERISTICS 

 ASSOCIATED WITH THE 

 RELEASE RESPONSE OF 

 WESTERN REDCEDAR 

 Literature Review 



Few significant associations between individual tree 

 growth and soil characteristics have been reported. 

 White and Leaf (1964, 1965) could not relate height 

 growth to amounts of total soil potassium but could 

 relate height growth to potassium levels near the solum 

 bottom. Amounts of soil phosphorus have been found 

 related (Hopmans and others 1978) and unrelated 

 (Pritchett and Llewellyn 1966) to tree growth. In 

 contrast, relating soil characteristics to site index has 

 been successful, resulting in several soil-site systems 

 available for evaluating site productivity (Gessel and 

 Lloyd 1950; Alban 1974). Often these soil-site evalu- 

 ation systems include other nonsoil variables such as 

 elevation and aspect that make their productivity 

 predictions more reliable (Steinbrenner 1979). Depend- 

 ing upon location and species, tree growth has been 

 found related to the amount of nutrients added to soil 

 through fertilization (Mayer-Krapoll 1956: USDA 1973). 



Methods 



DATA COLLECTION 



An integrated soil sample of the top 12 inches (30.5 

 cm) of mineral soil was collected from each of the 5 

 points within a cluster. The upper 12 inches (30.5 cm) 

 of soil has been shown to include the largest proportion 

 of conifer roots (Powers 1976; Eis 1974). The samples 

 were then combined in a shaker to form one soil 

 sample for each stand. The composite samples for each 

 stand were then chemically analyzed by the University 

 of Idaho College of Agriculture Plant and Soil Analytical 

 Laboratory. These chemical analyses quantified 14 

 characteristics of the soils from the 15 released stands 

 of western redcedar (table 5). 



Table 5.— Chemical characteristics of the soil from 15 stands of released western redcedar 



Characteristic 



Mean 



Standard 

 deviation 



Maximum 



Minimum 



PH 



5.70 



0.37 



6.15 



5.05 



Phosphorus (ppm) 



3.00 



1.90 



6.80 



1.00 



Potassium (ppm) 



2448.00 



788.50 



3800.00 



1190.00 



Organic matter (%) 



9.13 



2.99 



14.60 



4.60 



Nitrate (ppm) 



1.20 



1.48 



5.20 



.10 



Ammonium (ppm) 



4.61 



2.12 



9.40 



2.00 



Electrical cond. ( jumhos) 



.15 



.06 



.34 



.09 



Boron (ppm) 



.09 



.06 



.19 



.00 



Sulfate (ppm) 



8.50 



5.00 



31.00 



4.00 



Zinc (ppm) 



2.86 



1.09 



5.88 



1.68 



Manganese (ppm) 



134.30 



48.20 



198.00 



39.00 



Copper (ppm) 



1.06 



.38 



1.80 



.60 



Iron (ppm) 



367.60 



113.00 



600.00 



246.00 



Total nitrogen (%) 



.25 



.09 



.48 



.13 



9 



