West Virginia Seed Sources of Balsam Fir

Research Bulletin 1191-99

Tree Density

Tree density is another important factor affecting the quality of Christmas trees and is also one that is improved through shearing and shaping. Having trees that are inherently dense would be very helpful and, as with tree shape, could help reduce shearing and shaping costs. In this study, trees were subjectively rated for density using a three-point scale: 1 = open, 2 = medium, and 3 = dense.

Differences Between Locations
Trees of the Blister Swamp (1.68) and Stone Coal Run (1.81) half-sib families had the best densities, near the medium rating. Trees of the North Carolina stand collections had the lowest rating (1.32), followed closely by those from Canaan Valley-Cortland Road (1.41) and Canaan Valley-State Park and Blister Run (1.52) (Table 5).

Differences Between Seed Sources
Best average density (2.13) was found for trees of SS-384 from Stone Coal Run. Eight of 10 trees from that area were among the one-third of families having the best ratings, and none were in the lowest one-third. Trees from the Blister Swamp collection also rated relatively high for density, with six of 10 being in the top-rated group and only one in the lowest-rated (Tables 3, 4, 5).

Trees of SS-425 from Canaan Valley-Cortland Road had the lowest density rating (1.25), and four of eight trees from that area were among the lowest-ranked group, and none were among the highest-rated. Trees of both seed sources from North Carolina were also among the lowest-rated group. For Blister Run trees, only one half-sib family was among the highest-ranked group, while four were among the poorest; for Canaan Valley-State Park, two families were among the top one-third, and six were among the bottom third (Tables 3, 4, 5; Figure 13).

Figure 13. Dense (SS 384, Stone Coal Run, left) and open (SS 416, Canaan Valley-Cortland Road, right) densities of 14-year-old trees.

Differences Within Seed Sources
Standard deviations for density ratings of individual trees varied from 17 to 42 percent of individual seed-source means (Table 5). For individual trees of SS-384 which were highest-rated (2.6, medium to dense), the range was from 1.5 to 3.0 (moderately open to dense, Figure 9), while for SS-425, having the most open trees (1.2, open), the range was from 0.5 (very open) to 1.5 (moderately open) (Figure 8).