Height Growth 



Our analysis of variance for the mean total height at 

 the end of the fifth growing season showed several sig- 

 nificant relationships at the 95 percent level of confi- 

 dence (table 1). Lodgepole pine seedlings were taller (13.4 

 inches or 34.1 cm) than ponderosa pine (10.8 inches or 

 27.5 cm), which, in turn, were taller than Douglas-fir 

 (8.8 inches or 22.3 cm). Trees were tallest on the dozer 

 strips (12.7 inches or 32.2 cm), and those on the 4-ft 

 (1.2-m) scalps (11.5 inches or 29.2 cm) were taller than on 

 the 2-ft (0.6 1-m) scalps (8.9 inches or 22.5 cm). 



For both lodgepole and ponderosa pine the heights 

 were significantly taller on the dozer strips and 4-ft 

 scalps than on the 2-ft scalps (fig. 5). For Douglas-fir, 

 the differences were not statistically significant. 



The initial height of Douglas-fir averaged 5.1 inches 

 (13 cm) with a range of 2 to 9 inches (5 to 23 cm). Pon- 

 derosa pine initial tree height averaged 3.2 inches (8 cm) 

 and ranged from 2 to 5 inches (5 to 13 cm), while that of 

 lodgepole pine averaged 4.7 inches (12 cm) with a range 

 of 2 to 7 inches (5 to 18 cm). We plotted fifth-year 

 heights over initial heights and found no apparent 

 relationship. 



At the end of the fourth growing season, the rate of 

 terminal leader elongation was increasing faster on the 

 dozer strips for all three species (fig. 6). The next fastest 

 rate increase was on 4-ft scalps for the pines. The 

 Douglas-fir rate of terminal leader elongation was similar 

 for 4-ft and 2-ft scalps. 



After five seasons, lodgepole pine averaged 55 percent 

 taller than Douglas-fir and 25 percent taller than pon- 

 derosa pine. Figure 7 shows the Grouse Creek site and 

 heights of several trees after 10 growing seasons. 



TREE HT (CM) 



STRIP 

 4-FT SCALP 



[XXX] 



2-FT SCALP 



LODGEPOLE PINE 



PONDEROSA PINE 



DOUGLAS - FIR 



Figure 5.— Average tree heights. Bars depict tree heights in cen- 

 timeters. Lines depict mean comparison by Gabriel (1978). Treat- 

 ment means with lines that overlap are not significantly different. 



6 



