i 1 , 



DISCUSSION 

 AND CONCLUSIONS 



Estimating height of one species simply 

 from measurements of another species has 

 definite limitations. Different species are not 

 equally sensitive to differences in various site 

 factors; consequently, the relations between 

 species-growth characteristics must become 

 more complex as site variation increases. 

 While several different physical environments 

 may give a similar numerical site index for 

 white pine, the relative height response of 

 another species may differ at each location, 

 depending on its reaction to the particular 

 combinations of environmental conditions. 

 For this reason, the use of the longer formula 

 may be warranted on specific areas that are 

 important. 



Site indexes were not compared directly at 

 this time because good site curves were not 

 available for all of the species associated with 

 western white pine. Also, results elsewhere 8 9 10 

 point out that comparisons of site indexes are 

 most successfully applied within areas of fair- 

 ly uniform environment. Since the environ- 

 ments within the western white pine type are 



characterized by extreme variation (even lo- 

 cally), future studies of comparative site index 

 must identify and measure the important site 

 variables that affect relations among the 

 type-species. 



While the prediction equations given in this 

 paper can be useful in making management 

 decisions, the user should be aware of their 

 limitations. Many of the source data have 

 been taken from plots in unmanaged second- 

 growth stands. Conditions of density and 

 species composition have no doubt affected 

 height-growth relations differently than they 

 would on intensively managed plots. These 

 equations should be used with these limita- 

 tions in mind. 



*Hodgkins. Earl J. Testing soil-site index tables 

 in southwest Alabama. Jour. Forestry 54: 261-266. 

 1956. 



s Foster, Ralph W. Relation between site indexes 

 of eastern white pine and red maple. Forest Sci. 

 5:279-291. 1959. 



l0 Della-Bianca. Tino, and David F. Olson, Jr. Soil- 

 site studies in Piedmont hardwood and pine-hard- 

 wood upland forests. Forest ScL 7:320-329. 1961. 



T 



