rates. Even with truly precise seed placement, the 

 more seeds that fail to germinate, the less unifor- 

 mity in seedling spacing. 



Figures 1 through 5 compare seed and seedling 

 spacing distribution for the high-germination (95 

 percent) seedlots. Each seedling location histogram 

 in each of the bottom rows looks very similar to the 

 one for seed placement above it. Because some 

 seeds didn't germinate, the seedling distribution 

 is slightly to the right of seed distribution along the 

 spacing scale. The poorer the germination for any 

 seedlot, the greater the displacement in the histo- 

 gram. Ideally, the seedling location histograms 

 should have only a few bars grouped around the tar- 

 get spacing, much like the hand-thinned seedling 

 histograms. 



In no case did the seedling spacing by the seeders 

 approach the even seedling distribution of the hand- 

 thinned plots (fig. 5). 



Histograms of three tests show the Summit Preci- 

 sion Seeder gave better seed and seedling distribu- 

 tion than the Oyjord Seeder: ponderosa pine at J. 

 Herbert Stone Nursery (fig. 3b), lodgepole pine at 

 Lucky Peak Nursery (fig. 2b), and noble fir at Wind 

 River Nursery (fig. 5). Histograms for other tests 

 show little difference between the two seeders. 



Figures 6 and 7 compare the distribution of seed 

 spacing with the distribution of the resulting seed- 

 ling spacing for the high- and low-germination 

 lots of Engelmann spruce at Lucky Peak and 

 Coeur d'Alene Nurseries. It is difficult to see a dif- 

 ference between the seed and seedling distribution 

 in any of the comparisons. The spacing of the high- 

 germination seedlots is only slightly better. Results 

 were similar for other species. 



Seedling Grade and Morphology 



After 2 years in the nursery, seedlings from eight 

 of the 13 tests were lifted and graded. Seedling 

 heights were not different for any of the sowing 

 treatments (table 5). In only two cases out of eight 

 did mean seedling caliper (table 5) and total dry 

 weight (table 6) differ between treatments: Engel- 

 mann spruce and lodgepole pine, both at Lucky Peak 

 Nursery. In both instances, mean seedling caliper 

 and total dry weight were less on plots sown by the 

 Oyjord Seeder than on plots sown by the Summit 

 Precision Seeder and hand-thinned plots. In the 

 case of lodgepole, seedlings grew larger ft-om the 

 treatments that produced lower seedling densities. 

 The initial seedling density was not different be- 

 tween treatments for Engelmann spruce, but the 

 Oyjord treatment had more doubles and blank 

 spaces. This is consistent with other studies where 

 decreased density increased seedling calipers (Boyer 



and South 1987; Brissette and Carlson 1987; Mullin 

 and Bowdery 1977; Richards and others 1973; 

 Scarborough and Allen 1954; van den Driessche 

 1984). Although the differences in seedling spacing 

 in the other species and seedlots were all significant, 

 evidently they were not great enough to significantly 

 affect seedling size. 



Cull rates and number of shippable trees don't 

 show an overall trend. Plots sown with the Oyjord 

 Seeder, however, produced as many or more trees 

 that met grading specifications as the Summit Preci- 

 sion Seeder and the hand-thinned plots (table 6). In 

 figure 8 we see how the average numbers decline for 

 each treatment fi-om seeds sown, to seedling density, 

 to shippable seedlings. The first three charts show 

 fairly consistent relationships. Mostly, more seed 

 was sown using the seedlots with 75 to 85 percent 

 germination than those with 95 percent. Often the 

 difference in germination rates and sowing rates 

 cancelled each other producing about the same num- 

 ber of established seedlings for the two seedlots in 

 each test. Hand-thinned plots generally produced 

 fewer seedlings in the shippable category than plots 

 sown with either seeder. Cull rates were often simi- 

 lar for hand-thinned plots and plots sown with ei- 

 ther seeder, but initial seedling densities were lower 

 on the hand- thinned plots. Several studies on 

 southern pines have shown an increase in the pro- 

 portion of shippable seedlings with a decrease in 

 seedbed density (Boyer and South 1986, 1987; Burns 

 and Brendemuehl 1971; Caulfield and others 1987; 

 Shoulders 1961). The hand-thinned treatment in 

 this study did not lower cull rates because wider 

 seedling spacing was not sufficient in most cases to 

 increase seedling size. Grading specifications are 

 based on size and other morphological characteris- 

 tics, health, and lifting damage. 



Two tests had very high cull rates: Engelmann 

 spruce at Lucky Peak and ponderosa pine at 

 J. Herbert Stone. Seedling grading specifications 

 were different at each nursery and for each species. 

 Slight differences in specifications could greatly in- 

 crease or decrease the number of shippable seedlings. 



CONCLUSIONS 



Neither of the two seeders exactly placed seed in 

 any of the tests described here. As a result, seedling 

 spacing was not uniform. However, even with 

 oversowing and hand thinning to the desired spac- 

 ing, no more seedlings met specifications. Hand 

 thinning was not successful in increasing seedling 

 heights. It increased mean caliper and total dry 

 weight in only two of eight tests. 



Placement of seed by the two seeders varied with 

 each species and nursery. Seed size and shape also 



7 



