3.0 r- 



X 



O 2.0 



1.0 - 



POLYETHYLENE 



WEEDED 



GLASS FIBER 



CONTROL 



DAMAGED TERMINAL 



NORMAL TERMINAL 



Figure 9. — Mean fifth-year heights of seedlings by treatment and terminal 



damage classes. 



Summary and Conclusions 



During the period from 1962 to 1964, ponderosa pine seedlings were outplanted in 

 four different tests at Zena Creek, Payette National Forest and one test (1964) at 

 Boise Basin Experimental Forest, Boise National Forest. All tests appear to have been 

 in the Daubenmires' (1968) Douglas -fir--Ninebark h.t. A variety of techniques to re- 

 duce or eliminate competition were tested. Site preparation tests included scalps 

 (from 2 to 6 feet wide), pits, furrows, burning, and natural undisturbed areas. For 

 the mulch tests, black polyethylene film, glass fiber blankets, and straw were used. 

 Simazine, a pre-emergence herbicide, was also tested. Some limited attempts were made 

 to characterize the site conditions and evaluate seedling responses to: aspect; soil 

 depth and moisture content; and summer precipitation and temperature. Seedling sur- 

 vival tallies were made throughout a 5-year period after each planting (Appendix II) . 

 Fifth-year height measurements were made on a number of plots. Some general conclu- 

 sions are warranted: 



1. All the practices which reduce vegetative competition improved survival. The 

 relative improvement increased with time. 



2. The better the survival the taller the trees in the fifth year when other 

 factors are held constant. 



3. The greater the summer precipitation (with good distribution over a period 

 of time), the better the survival. 



Some additional conclusions were made as a result of individual tests. Naturally, 

 these conclusions are limited to the Douglas-fir-- Ninebark h.t. in the Idaho Batholith. 

 The tests were not specifically designed to obtain some of the conclusions, but the 

 observations and results from the series seem to support them. Confidence in these 

 conclusions is indicated as follows: * = statistically significant test assuming 



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