Practical Guidelines for Producing Longleaf Pine Seedlings in Containers

Barnett, James P.; McGilvrary, John M.  1997. Practical guidelines for producing longleaf pine seedlings in containers. Gen. Tech. Rep. SRS-14. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 28p. Introduction Of all the southern pines, many consider longleaf pine (Pinus palustris Mill.) the most valuable in terms of wood-product quality, aesthetics, and resistance to fire, insects, and disease. In the presettlement era, an estimated 60 million acres of the longleaf pine ecosystem extended from east Texas through the lower Coastal Plain to Virginia (fig. 1). Heavily harvested in the late 1800's and early 1900's, few longleaf stands survived. By 1935, only about 6 percent of old-growth longleaf pine remained in Louisiana (Wahlenburg 1946). Few seed trees endured these harvests, and much of the area was converted to other species or abandoned to grassland (fig. 2). Today, natural regeneration is only feasible on a small portion of the area in the longleaf pine type. Because longleaf pine is considered a desirable tree, why have we failed to regenerate more of the longleaf sites? The answers to this question are related to the unique botanical characteristics of the species: (1) low and infrequent seed production, (2) a seedling "grass" stage characterized by delayed stem elongation, (3) poor storability of bare-root nursery stock that results in low survival, and (4) seedling intolerance to shade conditions caused by competition.
		Figure 1—Virgin stand of longleaf pine near Flatwoods, LA, is typical of those found across the lower Coastal Plain before harvest in the late 1800 and early 1900's.
		Figure 2—Cutover longleaf pine forest that remained a grassland until reforested several decades later. The stumps were removed and processed for naval stores' products.

The knowledge and technology to reestablish longleaf pine by planting bare-root nursery stock have improved significantly in the last decade. The components of successful regeneration include: (1) well-prepared, competition-free sites; (2) healthy, top-quality, fresh planting stock; (3) meticulous care of stock from lifting to planting; (4) precision planting; and (5) proper post-planting care. All these elements are essential to successful planting of bare-root stock. Because controlling all five elements is difficult in many cases, planting success with bare-root longleaf pine stock remains elusive. These same components apply to container stock, where regeneration success is markedly better. Therefore, many silviculturists now prefer to plant container longleaf pine seedlings.

Numerous studies have demonstrated that under adverse planting conditions, such as poor sites, conditions of moisture stress, and out-of-season planting, container seedlings survive and grow better than bare-root stock (Barnett and McGilvray 1993). These improved survival and growth rates are generally attributed to root systems that remain intact during lifting while roots of bare-root plants are severely damaged. Thus, container seedlings experience a significantly shorter period of transplant shock or adjustment than bare-root seedlings.

Successful production of container seedlings requires thoughtful planning before sowing and daily attention while growing (Landis and others 1994). The goal should be to produce longleaf pine seedlings with root-collar diameters of at least one-fourth inch, an abundant presence of secondary needles, and a healthy root system with obvious mycorrhizal development. This paper provides basic information that will help nursery managers produce good quality longleaf pine container stock.

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