Figure Z. — Shoun above is a natural Douglas- fir tree before and after 

 one-half of the live crown was ipruned from midtree. Lower branches 

 were retained for future stump culture. 



Thicket Thinning 



Douglas-£ir often grows in thickets dense enough to severely restrict crown devel- 

 opment on individual trees. Consequently, their marketability as Christmas trees is 

 reduced. We sought to determine how three different levels of thinning affect the 

 quantity and quality of trees that could be harvested in these thickets, both initially 

 and subsequently. The three thinning levels were based primarily on ocular estimates 

 of light, medium, and heavy, using the following criteria: 



1. Light . --Badly deformed Douglas-fir and all other species removed plus a few 

 merchantable Christmas trees. Residual stand was still crowded with an average spacing 

 of less than 2 feet between trees. 



2. Medium . --Badly deformed Douglas-fir and all other species removed plus some 

 merchantable Christmas trees. Residual stand was less crowded than above but there was 

 still some side shading. 



3. Heavy . --Badly deformed Douglas -fir and all other species removed plus many 

 merchantable Christmas trees. Residual stand was moderately open with very little side 

 shading. 



4 



