Overstory Retention and Stock Type Impact Survival and Growth of Underplanted Shortleaf Pine Beneath a Hardwood Canopy

This study was established to evaluate underplanting as a method of reestablishing a shortleaf pine (Pinus echinata Mill.) component to a dry upland hardwood stand in the Piedmont region of the southeastern United States. Replicated treatment plots were harvested to retain four levels (approximately 0, 3, 7, and 10 m2 of basal area per hectare) of residual overstory density. One-year-old containerized seedlings with both smaller (93.4 cm3) and larger (113.1 cm3) plugs and bareroot seedlings were underplanted beneath the residual overstory treatments. After five growing seasons, seedling survival averaged 61% and was not meaningfully affected by residual overstory density. Seedling height growth ranged from 1.42 m to 2.61 m and was inversely related to residual overstory density. Containerized seedlings with larger plugs had the highest survival (77.4%) and best height growth (2.11 m), followed by containerized seedlings with smaller plugs (64.3%, 1.76 m) and bareroot seedlings (40.2%, 1.85 m). The results of this study indicated that underplanting containerized seedlings, particularly those with higher plug volume and greater plug depth, was a suitable option for reestablishing shortleaf pine on drier, hardwood dominated upland sites in the Piedmont. However, even low levels of overstory retention suppressed seedling height growth after a few years. Study Implications The study was conducted on a dry upland site typical of the North Carolina Piedmont. Retaining up to 10 m2 ha–1 of oak and hickory overstory basal area did not strongly affect survival among underplanted shortleaf pine seedlings after five growing seasons. However, overstory cover as low as 3 m2 ha–1 had negative effects on height growth of underplanted seedlings over the same time period. Height growth declined as overstory density increased. Containerized seedlings had better survival than bareroot seedlings. Further improvements in survival and height growth were realized by planting containerized seedlings with higher plug volume and greater plug depth.

Effect of sowing pattern and density on the quality of one-year-old Austrian pine bareroot seedlings

Austrian pine (Pinus nigra Arnold) seedlings are frequently used for afforestation/reforestation and restoration practice in Serbia. Indeed, the seedlings of various stock types are produced by almost all forest nurseries in Serbia and bareroot seedlings are mostly common. The aim of this study is to analyze the method of sowing and sowing density on some morphological characteristics and quality of one-year-old Austrian pine seedlings. Sowing in rows and random sowing across all seedbed space were performed. In both cases, the sowing density (R1 - 8 g m-1, R2 - 40 g m-2) and half of the recommended sowing density (S1 - 4 g m-1, S2 - 20 g m-2) were applied. Seedlings from both treatments had average height and root collar diameter values in the range of 4.91 to 5.73 cm, and 1.25 to 2.34 mm, respectively. Observed characteristics of seedlings (height - H, root collar diameter - RCD, root length - RL, dry weight of shoot - SDW, root - RDW and seedlings - SLDW, sturdiness coefficient - SQ and quality index - QI) were conditioned by treatment (One-Way ANOVA, p<0.05). Shoot to root ration was similar at seedlings of all treatments and ranged from 1.33 to 1.63. In both cases, decreased density produced better results. The combination of lower sowing density (20 g m-2) and sowing in all seedbed areas (S2) provided the best seedlings with QI - 0.21.

Influence of Root System Characteristics on Black Spruce Seedling Responses to Limiting Conditions

Roots directly affect planted seedling adaptation to new growing conditions at reforestation sites. To test the influence of root characteristics on the short-term response of seedlings to limiting resources (water, nutrient, or oxygen), we conducted two experiments. We compared (1) the growth and physiology of three types of four-year-old black spruce (Picea mariana (Mill.) BSP) seedlings (Containerized, highly developed initial roots restricted to a plug; bareroot, less developed but unrestricted initial roots; deeply-planted containerized, restricted initial and adventitious roots) to different combinations of irrigation and fertilization. We also investigated (2) the cellular plasticity of adventitious and initial roots to three irrigation regimes including flooding. Bareroot seedlings had better relative growth rates in height than containerized seedlings, probably due to their larger initial size. On the other hand, containerized seedlings took better advantage of fertilization, as shown by a higher relative growth rate in diameter compared to bareroot seedlings and were less affected by water limitation, possibly due to the root plug acting as an additional water reserve capacity. For containerized seedlings, the presence of adventitious roots was beneficial to height growth and physiological performances compared to seedlings with initial roots only. Adventitious roots showed great cell plasticity, particularly under flooding conditions.

Large Planting Stock Type and Mechanical Release Effects on the Establishment Success ofPicea glaucaPlantations in Quebec, Canada

We established four experimental plantations to evaluate the main and interaction effects of timing (year of application) of mechanical release and stock type (containerized or bareroot) on the establishment success of largePicea glaucaseedlings eight years after outplanting on high-competition sites in Quebec (Canada). We also monitored percent cover and height of target vegetation groups as well as the amount of photosynthetically active radiation available to crop trees. Our results indicate that the use of large containerized or bareroot stock had limited effects on seedling growth, although bareroot seedlings presented higher mortality than containerized seedlings. Mechanical release enhanced seedling growth, compared to the control. Delaying treatment by two years impacted crop tree dimensions, although differences were minimal. Survival was not affected. We conclude that large containerized seedlings should be favoured over bareroot stock for reforestation on high-competition sites and that the release guidelines developed for standard size seedlings are applicable to the large dimensionP. glaucastock tested in this study.

Growth of Longleaf and Loblolly Pine Planted on South Carolina Sandhill Sites

Performance of longleaf (Pinus palustris Mill.) and loblolly pine (P. taeda L.) were compared 15–19 years after outplanting on 10 different sites in the sandhills of South Carolina. The study was established from 1988 to 1992 with bareroot seedlings artificially inoculated with Pisolithus tinctorius (Pt) or naturally inoculated with mycorrhizae in the nursery. A containerized longleaf pine treatment with and without Pt inoculation was added to two sites in 1992. Effects of the Pt nursery treatment were mixed, with a decrease in survival of bareroot longleaf pine on two sites and an increase in survival on another site. The containerized longleaf pine treatment substantially increased survival, which led to greater volume compared with bareroot longleaf pine. Loblolly pine yielded more volume than longleaf pine on all sites but one, where survival was negatively affected by fire. Depth of sandy surface horizon affected mean annual height growth of both loblolly and longleaf pine. Height growth per year decreased with an increase in sand depth for both species. Multiple regression analysis of volume growth (ft3/ac per year) for both species indicated a strong relationship to depth of sandy soil and survival. After 15–19 years, loblolly pine has been more productive than longleaf pine, although longleaf pine productivity may be equal to or greater than that of loblolly pine on the soils with the deepest sandy surface layers over longer rotations.

Artificial Oak Regeneration in Historic Woodlots at Gettysburg National Military Park

To restore woodlots at Gettysburg National Military Park (GNMP) to Civil War condition, in which oak was the dominant vegetation, the effects of woodlot, canopy treatment, and fencing treatment on the survival and height of northern red oak (Quercus rubra) direct-seeded seedlings, planted seedlings, and planted saplings were examined. Three 0.20 ha circular canopy treatments (closed canopy, partially open canopy, and completely open canopy) were assigned within each of three woodlots. Each treatment was replicated three times within each woodlot. Within each canopy treatment unit, two paired fenced and unfenced plots were established. At each pair of plots, 40 acorns, eight 2-0 bareroot seedlings, and six 4-0 bareroot saplings were planted. Foraging damage by white-tailed deer (Odocoileus virginianus) and small mammals was monitored during the second and fourth growing seasons after canopy treatment. At the end of the second and fourth growing seasons, survival and height were recorded for each of the three sources of regeneration. Four-year survival of direct-seeded seedlings and planted seedlings was maximized on fenced plots. Planted sapling 4 yr survival and height were greatest in the partially or completely open canopy. To maximize 4 yr height of direct-seeded seedlings and planted seedlings, the completely open canopy, fence treatment combination was recommended. All three sources of northern red oak had potential for regenerating GNMP woodlots. Due to rapid height growth, either direct-seeded seedlings or planted seedlings may be preferred. North. J. Appl. For. 20(3):131–136.

Effects of storage temperature on physiological characteristics of fall-lifted white spruce (Picea glauca) bareroot seedlings

Fall-lifted white spruce (Picea glauca (Moench) Voss) bareroot seedlings were winter stored at -2, -4, and -6°C. The electrolyte leakage and carbohydrate content were periodically measured in roots and shoots during storage. Water relations, gas exchange, bud flushing, and root growth potentials were measured after 4 and (or) 7 months of frozen storage. Shoots and roots of seedlings stored at -6°C had higher electrolyte leakage compared with those stored at -2 and -4°C. Sugar levels increased as a result of frozen storage and were higher in seedlings stored at -4 and -6°C compared with those at -2°C. Root total nonstructural carbohydrate (TNC) contents declined with storage duration in all storage temperatures. However, seedlings stored at -4 and -6°C maintained slightly higher root TNC than those stored at -2°C. Needle TNC in seedlings stored at -4 and -6°C did not change; however, it declined in seedlings stored at -2°C. Storage temperatures of -4 and -6°C also altered seedling water relations with seedlings stored at these temperatures having lower osmotic potentials at turgor loss point and at full hydration and less elastic cell walls compared with seedlings stored at -2°C. Lower storage temperatures decreased root growth potentials and delayed bud flushing following planting.