Increasing Pine Survival and Early Growth by Planting “morphologically Improved” Seedlings

“Morphologically improved” seedlings (large-diameter seedlings grown at low nursery spacings) have a higher probability of survival (about 5% better) than regular seedlings since they have larger root systems, a higher root-weight ratio (root dry weight/seedling dry weight), and have a greater root growth potential. In addition, these seedlings will grow faster during the first several years after planting. On some sites, morphologically improved seedlings will be larger in diameter at time of planting than “regular” seedlings that planted a year earlier. Morphologically improved seedlings are not available at many nurseries but they are produced at several industrial, and privately owned nurseries. The potential economic gains from planting morphologically improved seedlings increases as planting density and harvest age decreases. When planted at 333 trees per acre, these seedlings may cost $6 to $15 more per acre but may return $24 to $74/acre (present value). Well-balanced seedlings that average 6-mm at the root collar may provide a one-year advance in stand development in comparison to seedlings that average 4 mm or less. At age 15, a one-year “boost” in stand development can provide 150 cubic feet (low site) to 400 cubic feet (high site) more wood per acre. Results from a number of studies indicate there is a substantial opportunity for increasing regeneration costs by substituting competitive seedlings rather than applying a high level of mechanical site preparation with marginal seedlings. Reducing the total amount invested in regeneration while maintaining acceptable survival and growth is a realistic goal for non-industrial landowners with limited funds.