THE PROBLEM 



The western white pine (Pinus monticola 

 Dougl.) forest type occupies about 2.4 mil- 

 lion acres of commercial forest land in the 

 northern Rocky Mountain region. Another 2 

 million acres or more could grow white pine, 

 but the species is not present in quantity be- 

 cause of past cutting practices or quirks of 

 nature. 



Management on these areas is difficult for 

 several reasons. White pine silvicultural prac- 

 tices have been especially complicated by 

 blister rust disease. Sites now occupied by 

 white pine, or that could grow it, generally 

 rank quite high in terms of production poten- 

 tial, but the characteristic steep slopes and 

 rough topography cause frequent and abrupt 

 changes in site quality. Also, species compo- 

 sition on land capable of growing white pine 

 is typically complex: as many as 10 species 

 occur on some sites. Common associates of 

 white pine are Douglas-fir (Pseudotsuga men- 

 ziesii var. giauca (Beissn.) Franco), western 

 larch (Larix occidentalis Nutt.), western hem- 

 lock (Tsuga heteropnylla (Raf.) Sarg.), grand 

 fir (Abies grandis (Dougl.) LindL), western 

 redcedar (Thuja, pile at a Donn), lodgepole pine 

 (P. contorta Dougl.), Engelmann spruce 



(Picea engelmannii Parry), and subalpine fir 

 (Abies lasiocarpa (Hook) Nutt.). 



The wide representation of species offers 

 the forest manager considerable latitude in 

 choosing a particular species or combination 

 of species to favor in future stand manage- 

 ment. Sound economic decision in manage- 

 ment planning requires knowledge of how the 

 performance of available alternative species 

 compares on specific sites. It is therefore im- 

 portant to know the comparative . height- 

 growth capabilities because height is presently 

 the best single indicator of site or yield 

 capacity. 



Methods for estimating comparative heights 

 have been developed for some of the species 

 capable of growing on white pine land. From 

 these, two important kinds of information can 

 be obtained. First, a prediction of height 

 growth of alternate species can be made from 

 information on white pine performance; sec- 

 ond, on lands where white pine is scarce or 

 absent, the capacity of the land to grow it 

 can be estimated from known heights of al- 

 ternate species. This information should be 

 useful in establishing preferential guides for 

 planting and thinning operations. 



METHODS 



PLOT DESCRIPTIONS 



One hundred and eight permanent plots in 

 northern Idaho western white pine stands ex- 

 tending from the Kaniksu National Forest 

 to the Clearwater National Forest were se- 

 lected for analysis. These plots provided suffi- 

 cient height data on white pine and other 

 species to be considered usable for this study. 

 The plots ranged in size from 0.1 acre to 2.0 



acres and had been measured at 5- or 10-year 

 intervals over varying lengths of time — some 

 for as long as 40 years. Most of the plots 

 were at elevations between 2,000 and 4,000 

 feet above sea level, but 13 were at higher 

 elevations, some approaching 5,000 feet. 

 Nearly 90 percent occupied topographic posi- 

 tions classified as upper, middle, and lower 

 slope; the remainder were classified as ridge 

 and flat (or bench) locations. 



