Predicting Regeneration 

 Establishiment With the 

 Prognosis Mo6e\ 



Dennis E. Ferguson 

 Clinton E. Carlson 



INTRODUCTION 



Forests of Idaho and Montana are quite diverse. Environmental conditions 

 support forest types ranging from dry ponderosa pine (Pinus ponderosa) for- 

 ests, to near-rain forests dominated by western redcedar (Thuja plicata) and 

 western hemlock (Tsuga heterophylla), to high-elevation subalpine fir (Abies 

 lasiocarpa) and whitebark pine (Pinus alhicaulis) forests where the growing 

 season is short. These forests are highly valued for timber, wildlife, water, 

 grazing, recreation, biological diversity, and esthetics. 



Management often involves the manipulation of conifers through timber 

 harvests, natural and artificial regeneration, site preparation, weedings, 

 and thinnings; control of competing vegetation such as shrubs, forbs, and 

 grasses; and control of insects, diseases, and wildfires. Manipulation of for- 

 ests changes the course of secondary succession which, in turn, affects the 

 future of these ecosystems. 



Land managers need to know how their actions affect the course of second- 

 ary succession. One particularly important effect is the regeneration of coni- 

 fers following timber harvest. Can cutover areas be regenerated in a timely 

 manner to desirable species having acceptable growth rates? Which of sev- 

 eral alternative silvicultural prescriptions should be used to reach desired 

 future conditions? 



Land managers compare alternative silvicultural prescriptions to determine 

 which one best meets management objectives. These comparisons need to 

 be quantified in a biologically meaningful and statistically sound manner. 

 Fortunately, the necessary information is available to quantify the regener- 

 ation process in much of the Western United States. 



The first requirement for predicting regeneration success is an understand- 

 ing of the sUvical characteristics of conifer species. Many research reports deal 

 with silvics of conifers found in the interior Western United States. For exam- 

 ple, Haig and others (1941) summarize many years of research in northern 

 Idaho that provides information on silvical characteristics of conifers and 

 the effects of silvicultural treatments on regeneration success. Many other 

 studies are also available; a good place to begin is Bums and Honkala (1990). 



The second requirement for predicting regeneration success is an ecologi- 

 cal land classification system. The habitat type system, first developed by 

 Daubenmire (1952), provides the framework for modeling secondary succession. 

 Today, more detailed habitat type classifications are available for Montana 

 (Pfister and others 1977), central Idaho (Steele and others 1981), and north- 

 em Idaho (Cooper and others 1991). 



The third requirement is a large number of managed stands that can be sam- 

 pled to represent independent variables in a regeneration model — number 

 of years since disturbance, site preparation, residual overstory density and 



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