Lodgepole pine grew more long roots and had a 

 greater total length of long roots than the other spe- 

 cies (table 4). Whether ponderosa pine or Engelmann 

 spruce was second best depended on the soil (fig. 6). 

 Ponderosa pine roots grew best in the peat-vermicuUte- 

 sandy loam soil, while Engelmann spruce showed more 

 root growth than ponderosa pine in the basaltic and 

 granitic soils. Douglas-fir produced the least long 

 root growth (table 4). 



Lodgepole pine grew the most short roots in the 

 peat-vermiculite-sandy loam soil, but Engelmann 

 spruce grew just as many short roots in the basaltic 

 and granitic soils. Ponderosa pine had as many short 

 roots as Engelmann spruce in the peat-vermiculite- 

 sandy loam soil (fig. 7). Douglas-fir produced the 

 fewest short roots in this test. The two pine species 

 exhibited the best mycorrhizal associations. Engel- 

 mann spruce was next best; Douglas-fir had only a 

 small number of mycorrhizal root tips. Douglas-fir 

 had a lower plant water potential than the other spe- 

 cies (table 4). 



Overall, root growth was best on the peat-vermiculite- 

 sandy loam soil, but the relationship is not quite so 

 simple. Engelmann spruce grew more roots in the 

 granitic soil than in the other two soils (figs. 6 and 

 7). Seedlings growing in the basaltic soil produced 

 the least root growth, the least shoot growth, and 

 lowest plant water potential. The granitic soil was 

 more conducive to mycorrhizal associations than the 

 basaltic (table 4). 



Lodgepole Ponderosa Douglas-fir Engelmann 

 pine pine spruce 



Figure 6 — Average number of roots longer 

 than 1.5 cm from 300 lodgepole pine, pon- 

 derosa pine, Douglas-fir, and Engelmann 

 spruce seedlings grown in the greenhouse 

 for 30 days (greenhouse experiment 2). 

 Seedlings were root dipped in one of four 

 materials or not dipped and potted in one 

 of three soils: basaltic, granitic, or peat- 

 vermiculite-sandy loam. 



Figure 7 — Average number of roots shorter 

 than 1 .5 cm from 300 lodgepole pine, pon- 

 derosa pine, Douglas-fir, and Engelmann 

 spruce seedlings grown in the greenhouse 

 for 30 days (greenhouse experiment 2). 

 Seedlings were root dipped in one of four 

 materials or were not dipped before being 

 potted in one of three soils: basaltic, gra- 

 nitic, or peat-vermiculite-sandy loam. 



Field Studies 



The first field test showed no significant difference 

 in lodgepole pine root growth after 30 days because 

 of the large variability and small sample of trees 

 (table 5). Survival was generally poor because of 

 pocket gopher activity, but the seedlings dipped in 

 vermiculite had a little higher survival. Most of the 

 mortality came during the first winter and second 

 growing season (fig. 8). Mean height figures were also 

 reduced because gophers sometimes clipped seedlings 

 off above ground but did not kill them. Still, the mean 

 heights for all treatments tripled in 3 years (fig. 9). 

 There was no significant difference between treat- 

 ments after 3 years (a = 0.05). 



In the second field test, seedlings root dipped in the 

 vermiculite slurry produced more new roots than those 

 in the vermiculite treatment and those that received 

 no treatment (table 6). The Aquagel® seedlings were 

 intermediate. There was little difference between 

 treatments in the mean length of the new roots longer 

 than 1.5 cm. 



Third-year mean seedling height and survival 

 showed little difference between the treatments 

 (table 6). Seedling growth was fair during the first 

 growing season, very poor during the second, and 

 poor in the third (fig. 10). The poor growth was due 

 to drought conditions on the site during July and 

 August of the first two growing seasons. Survived 

 dropped considerably between the first and second 



7 



