Survival: As shown in Table 1, survival of trees on the 80 study plots having effective weed control averaged 86.9 percent for all plots, with a range of 16 to 100 percent. In individual plantings, there were areas where survival was 0, and those areas were usually associated with "very wet" conditions, particularly fine textured soils with poor internal soil drainage in combination with concave-shaped surfaces. Conversely, best growth of trees was most often associated with well to moderately well-drained, loam to silt-loam textured soils.
Height Growth: After seven growing seasons in the field, total heights of trees averaged 1.75 m (6.5 ft) for all plots, while for individual plots, the range was from 0.82 to 2.41 m (2.7 to 7.9 ft); there were individual trees within plots as small as 0.50 m (1.6 ft) and as tall as 3.00 m (9.8 ft). From these figures, it is apparent that the average total height for all trees in the study, after seven growing seasons, was at or near marketable size, while some trees could have been harvested after not more than six years. The slowest-growing trees on plots were usually associated with lower survival rates and with conditions similar to those noted for poor survival.
In plots where growth was good, trees had been sheared at varying intensities for two or more years, so comparisons between total heights may not be completely reflective of site and management conditions. To provide a more common basis for comparison, heights after four growing seasons in the field (four-year heights) were also measured, with trees averaging 0.91 m (3.0 ft) and a range in averages for individual plots from 0.42 to 1.40 m (1.4 to 4.6 ft). For individual trees in plots, four-year heights ranged from 0.29 to 1.68 m (1.0 to 5.5 ft).
Needle Lengths: Needle lengths of trees also varied greatly on plots, with an average of 19.1 mm (0.75 in) and a range of 13 to 27 mm (0.5 to 1.1 in), approximately the same as that noted for needle lengths in a study of variation between half-sib progeny of different West Virginia balsam fir seed sources (Brown, 1999).
Foliage Color: Evaluations of the color of the upper surface of needles showed an average rating for all plots of 3.4 - yellow/green to green. Ratings for individual plots were as low as 2.2 -green/yellow (with individual trees at the yellow rating) and as high as 4.2 - green (with many individual trees at or above the blue/green rating). Almost invariably, the poorest color occurred on plots having "wetter" soils.
Foliage Weights: Other studies conducted by the author have found that comparative weights of uniform pieces of foliage can be a good indicator of overall growth and vigor of Christmas trees growing under varying conditions or receiving different experimental treatments (fertilization, weed control, etc.). For trees sampled in this study, there was a wide range in foliage weights, with an average of 1.6 grams per four-inch piece and a range of 1.0 to 2.2 grams for individual plots. Again, the lowest values were generally found on "wetter" sites.
Numbers of Lateral Limbs: During the study, lateral limb counts were made on terminal shoots that had developed in 1994 or 1995. For all plots, the average number was 16.4, with an eight-fold range (4 to 30) on individual plots. Lower counts were invariably on some of the slowest-growing trees having 1994/1995 terminals which averaged as low as one inch in length. The numbers of laterals per unit length of terminal shoot averaged 1.7 per inch, with a range of 1.0 to 3.0 per inch, with no apparent relationship to varying site and management factors.
Needle Retention: The number of years that needles were retained on lateral limbs varied considerably for trees on plots, averaging 3.43, with a range of 2.4 to 4.4 years, and some individual trees having needles only on the most recent shoot growth. As noted for other characteristics, poorest needle retention was usually associated with conditions where survival and growth were poorest and particularly on "wetter" soils.