Table 9 . --Christmas tree production (per acre) from initial thinnings 



and subsequent harvests 





Stand 



density 



: Christmas 



tree production 





Thinning :- 

 level : 



Before 

 thinning 



: After 

 : thinning 



: From initial : 

 : thinning : 



From subsequent 

 harvests 



■ Total 



Light 



Medium 



Heavy 



15,100 

 12,920 

 17,160 



12,300 

 9,600 

 6,800 



80 

 200 

 880 



980 

 820 

 440 



1,060 

 1,020 

 1,320 



Average 



15,060 



9,567 



386 



747 



1 ,133 



Table 10 .--Percentile Christmas trees produced in thickets thinned to 

 three different levels according to grade and size 



Thinning 



Tree grade 





Height classes 





treatment ; 



Premium : Standard : Utility 



2-ft. 



: 4-ft. : 6-ft. : 



8-ft. 



Light 



8 



59 



33 



31 



43 



18 



8 



Medium 







46 



54 



27 



55 



16 



2 



Heavy 



5 



77 



18 



14 



63 



23 







Average 



4 



61 



35 



24 



54 



19 



3 



Nearly all of the Christmas tree production came from dominant or codominant trees 

 of good and fair vigor--96 percent of the merchantable Christmas trees were classified 

 either dominant or codominant, while 70 percent were of good vigor and 29 percent of 

 fair vigor when the study was initiated. These figures were essentially the same for 

 all three thinning intensities. 



Stand vigor declined under all three thinning intensities. During the first 6 

 years after thinning, 28 percent of the trees dropped at least one vigor class; i.e., 

 from good to fair or fair to poor, while only 5 percent of the trees increased in vigor 

 The remaining high percentage (67 percent) of trees showing "no change" is somewhat 

 deceiving. Most of these trees were of poor vigor at the start of the study; thus, 

 there was no way for them to drop into a lower vigor class. In general, good vigor 

 trees maintained their vigor; fair vigor trees declined; and poor vigor trees died or 

 barely stayed alive. Differences between thinning treatments were minor. 



Crown classes showed the same trend as vigor. Over a third of the trees dropped 

 into lower crown classes; i.e., from dominant to codominant, codominant to intermediate 

 or intermediate to suppressed. Only 1 percent increased their crown position. Most of 

 the trees that did not change crown class were suppressed trees that could not drop 

 into a lower classification. 



Records are not complete for the last remeasurement ; but where recorded, vigor and 

 crown class continued to decline. 



Mortality started early and continued throughout the entire study period. Approx- 

 imately one-fourth of all the "leave" trees in each thinning treatment died during the 

 10-year period after thinning (table 11). 



12 



