INTRODUCTION 



Western white pine (Pinus monticola Dougl.) has long been an important component of 

 the forests of north Idaho, but the introduction of blister rust [Cronartium vibicola 

 J.C. Fisch. ex Rabenh.) and the ensuing losses to the disease has dissuaded land mana- 

 gers from attempting to manage the species. Now, as efforts to produce trees resistant 

 to the disease show some promise, land managers are again beginning to include white 

 pine in their regeneration programs. In the long run, the natural selection process 

 should produce trees with sufficient blister rust tolerance or resistance to allow natu- 

 ral regeneration. For the present and near future, however, planting of resistant seed- 

 lings will be needed. 



The production and utilization of resistant planting stock involves much more than 

 just securing an adequate level of resistance in a sufficient proportion of the seedlings 

 to be planted. The manager wants the seedlings to survive and grow on the sites he wants 

 to plant and he wants them to grow at a rate which fully utilizes the potential of the 

 site. Attempting to achieve such an ideal match of seedling and site is not a realistic 

 goal at present because of our lack of knowledge of both trees and sites. Also, the 

 costs to approximate such a match would likely exceed the returns from greater yields 

 as the limits of the site are approached. The realistic goal for the present is to 

 attempt to achieve a balance that incorporates our present biological information and 

 approximate costs with expected growth rates and economic returns. 



This paper will discuss past and current investigations into variation in growth 

 of western white pine in nursery trials and several experimental plantations. The 

 conclusions of the research will then be translated into guidelines for distributing 

 seed from orchards that have already been established and to evaluate alternative 

 designs for future seed orchards. 



PRIOR RESEARCH 



During the past 20 years several reports on variation in western white pine have 

 appeared. Squillace and Bingham (1958) opened the series with a report of "localized 

 ecotypic variation" based on germination and early growth of seedlings from quite dif- 

 ferent sites within a small area. They concluded that seedlings from trees growing on 

 poorer sites were shorter in nursery trials than those from trees growing on better 

 sites. Germination of seeds in a sucrose solution was higher for poorer site trees 

 than for better site trees. In a low-elevation nursery, seedlings from low-elevation 

 trees were taller than those from high-elevation trees, but when transplanted to a 

 high-elevation test site the seedlings from the high-elevation trees grew faster. On 

 the basis of those findings, and other considerations, the applied program to produce 

 blister rust resistant western white pine was subdivided into three elevational zones 

 or breeding units with a seed orchard planned for each. These zones were: (1) Low- 

 elevation--areas below 1,000 m; (2) mid-elevation--areas between 1,000 m and 1,250 m; 

 and (3) high-elevation--areas above 1,250 m. 



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