Longleaf Pine Seedlings Research Articles

Growing Longleaf Pine Seedlings in Containers

We provide basic guidelines for nursery production of longleaf pine (<i>Pinus palustris</i> P. Mill. [Pinaceae]) seedlings in containers. The best seedlings are spring sown, grown outdoors in full sun in cavities with a 100-ml (6 in³) volume, 11-cm (4.5 in) depth, and a density around 535 seedlings per m² (50/ft²). A 1:1 peat moss:vermiculite medium adjusted to pH 4.5 to 5.5 and amended with control-release or soluble fertilizers works well. Planting of container stock generally improves reforestation success because survival is good, the planting season can be extended, and therefore, restoration of the longleaf pine ecosystem is enhanced.

Mulch and Hexazinone Herbicide Shorten the Time Longleaf Pine Seedlings are in the Grass Stage and Increase Height Growth

Herbaceous plant control with mulchor hexazinone herbicide influenced planted longleafpine (Pinus palustris Mill.) seedling totalheight on a silt loam site in central Louisiana. Thesite had been sheared and windrowed in 1991 and rotarymowed before three treatments were established in arandomized complete block design: (1) Untreatedcheck: no herbaceous plant control after planting;(2) Five mulches: on each plot, five randomlyassigned mulches were placed around seedlings; themulches were either a mat of cotton, hemlock andpolyester, pine straw, woven polypropylene, orperforated polyethylene; and (3) Hexazinone: theherbicide hexazinone at 1.12 kg active ingredient/hawas annually sprayed in the first two growing seasonsover the rows of unshielded seedlings. The longleafseedlings were planted in February 1993.

Effects of long-term fire exclusion on tree species composition and stand structure in an old-growth Pinus palustris (Longleaf pine) forest

Frequent fire is an integral component of longleaf pine ecosystems, creating environmental conditions favoring survival and growth of juvenile pines. This study examined stand structure, species composition, and longleaf pine regeneration in an old-growth tract of longleaf pine forest (Boyd Tract) experiencing long-term (>80 yr) fire exclusion in the Sandhills of North Carolina. Sampling of woody stems (i.e.,2.5 cm diameter at breast height) and tallies of longleaf pine seedlings were carried out in plots established randomly on upland, mesic areas and lowland, xeric areas within the Boyd Tract. Dominant woody species in mesic plots were black oak, hickories, and large, sparse longleaf pines. Xeric plots had high densities of turkey oak with the large longleaf pines, as well as higher frequencies of smaller longleaf stems. These differences between areas were associated with higher clay content of upland soils and higher sand content of lowland soils. Age-class frequency distributions for firesuppressed longleaf pine following the last wildfire at the Boyd Tract approximately 80 yr ago contrasted sharply with data from an old-growth longleaf tract in southern Georgia (Wade Tract) that has been under a long-term frequent fire regime. Post-burn recruitment for the Boyd Tract wildfire appears to have been initially high on both site types. Longleaf pine recruitment diminished sharply on the mesic site, but remained high for60 yr on the xeric site. Currently, longleaf pine regeneration is minimal on both site types; several plots contained no seedlings. Sharp contrasts in longleaf pine dominance and stand structure between the Boyd and Wade Tracts demonstrate the importance of large-scale disturbance, especially hurricanes and fire, in shaping the structure and function of longleaf pine ecosystems of the southeastern United States. In particular, long-term exclusion of fire on the Boyd Tract has altered stand structure dramatically by permitting hardwoods to occupy at high densities the characteristically large gaps between longleaf stems that are maintained by fire and other disturbances.

Anatomical and Morphological Alterations in Longleaf Pine Needles Resulting from Growth in Elevated CO2: Interactions with Soil Resource Availability

Studies of anatomical changes in longleaf pine (Pinus palustris Mill.) needles for plants exposed to elevated atmospheric CO2 may provide insight into the potential influences of global CO2 increases on plant productivity. Longleaf pine seedlings were grown in open‐top field chambers supplied with either ambient (∼365 μmol mol−1) or elevated (∼720 μmol mol−1) atmospheric CO2 for 20 mo. Two levels of soil nitrogen (40 and 400 g ha−1 yr−1) and two soil moisture regimes (−0.5 or −1.5 MPa predawn xylem pressure potential) were used in combination with CO2 treatments. Needle tissue was collected 12 and 20 mo after treatment initiation and subjected to light and scanning electron microscopy. There was no effect of elevated CO2 on stomatal distribution or the proportion of internal leaf area allocated to a given tissue type at either sampling date. Although the relationships between vascular, transfusion, mesophyll, and epidermal tissue cross‐sectional areas to total leaf cross‐sectional areas appear nonplastic,...

Gap-phase regeneration in longleaf pine wiregrass ecosystems

Naturally regenerated seedlings of longleaf pine are typically observed to cluster in the center of tree fall canopy gaps and be encircled by a wide zone from which they are generally excluded. Twelve representative canopy gaps distributed across 600 ha of a naturally regenerated uneven-aged longleaf pine forest in the sandhills of north central Florida were examined to determine which aboveground and belowground factors are responsible for development of this seedling exclusionary zone. Within 12 m of adult trees growing along the gap edge, significantly fewer longleaf pine seedlings were present. The canopy of overstory trees, however, extended only 4–5 m into the gap. The relatively open structure of the longleaf pine canopy (57% cover) allowed photosynthetically active radiation (PAR) to be evenly distributed upon the forest floor across each canopy gap. Thus, light availability was not related to pine seedling clustering near gap centers. Significantly greater forest litter mass beneath adult trees (5 Mg ha −1) could result in fires more intense than would be supported by the litter mass near gap centers (2.5 Mg ha −1). However, litter mass was significantly elevated only within 4 m of the gap edge. The fine root biomass within 12 m of the gap edge (3–4.5 Mg ha −1) was two to six times that measured near the gap center and most closely coincided with the width of the seedling exclusionary zone along the margin of each gap. Thus, while the canopy of adjacent adult trees may indirectly influence seedling mortality through deposition of needle litter and greater fire intensity within 4 m of the gap edge, the root systems of these adults also appear to directly compete with seedlings within 12–16 m of the gap edge for limited site resources. To effectively regenerate and sustain longleaf pine wiregrass ecosystems, caution should be used in prescribing single-tree selection harvest methods so as not to create gap openings so small (<30 m diameter) that intraspecific competition from adult trees totally excludes seedlings. Group selection methods may prove more effective in creating canopy gaps of sizes suitable (≥40 m diameter) for ensuring that intraspecific competition from adults is maintained at a level which allows for survival and growth of seedlings. Shelterwood and deferment methods may also prove useful where more open canopy conditions are desired. However, the pine seedlings' need for light cannot be used as an appropriate rationale for application of clearcutting methods.

Influence of CO2 enrichment and nitrogen fertilization on tissue chemistry and carbon allocation in longleaf pine seedlings

One-year-old, nursery-grown longleaf pine (Pinus palustris Mill.) seedlings were grown in 45-L pots containing a coarse sandy medium and were exposed to two concentrations of atmospheric CO2 (365 or 720 mol-1) and two levels of nitrogen (N) fertility (40 or 400 kg N ha-1 yr-1) within open top chambers for 20 months. At harvest, needles, stems, coarse roots, and fine roots were separated and weighed. Subsamples of each tissue were frozen in liquid N, lyophilized at -50 EC, and ground to pass a 0.2 mm sieve. Tissue samples were analysed for carbon (C), N, nonpolar extractives (fats, waxes, and oils=FWO), non-structural carbohydrates (total sugars and starch), and structural carbohydrates (cellulose, lignin, and tannins). Increased dry weights of each tissue were observed under elevated CO2 and with high N; however, main effects of CO2 were significant only on belowground tissues. The high N fertility tended to result in increased partitioning of biomass aboveground, resulting in significantly lower root to shoot ratios. Elevated CO2 did not affect biomass allocation among tissues. Both atmospheric CO2 and N fertility tended to affect concentration of C compounds in belowground, more than aboveground, tissues. Elevated CO2 resulted in lower concentrations of starch, cellulose, and lignin, but increased concentrations of FWO in root tissues. High N fertility increased the concentration of starch, cellulose, and tannins, but resulted in lower concentrations of lignin and FWO in roots. Differences between CO2 concentrations tended to occur only with high N fertility. Atmospheric CO2 did not affect allocation patterns for any compound; however the high N treatment tended to result in a lower percentage of sugars, cellulose, and lignin belowground.

Elevated atmospheric CO2 differentially affects needle chloroplast ultrastructure and phloem anatomy in Pinus palustris: interactions with soil resource availability

ABSTRACTThe response of forest species to increasing atmospheric CO2, particularly under resource limitations, will require study in order to predict probable changes which may occur at the plant, community and ecosystem levels. Longleaf pine (Pinus palustris Mill.) seedlings were grown for 20 months at two levels of CO2 (365 and 720 μol mol1) in two levels of soil nitrogen (4 and 40 g m−2), and with two levels of soil moisture (–0·5 and –1·5 MPa xylem pressure potential). Leaf tissue was collected in the spring (12 months exposure) and autumn (20 months exposure) and examined using transmission electron microscopy (TEM) and light microscopy. During early spring, elevated CO2 magnified effects of N and water treatment on starch accumulation and in some cases contributed to altered organization of mesophyll chloroplasts. Disruption of chloroplast integrity was pronounced under elevated CO2, low N and water stress. In autumn, needles contained little starch; however, chloroplasts grown under high CO2 exhibited stress symptoms including increased plastoglobuli and shorter grana. A trend for reduced needle phloem cross‐sectional area resulting from fewer sieve cells was also observed under elevated CO2. These results suggest that, in nature, longleaf pine seedlings may not benefit from a doubling of CO2, especially when soil resources are limiting.

Fungicides Improve Field Performance of Stored Loblolly and Longleaf Pine Seedlings

Abstract Seedlings of loblolly and longleaf pine lifted in December, January, and February were treated with either benomyl or ridomil before cold storage. Along with an untreated control, they were planted after cold storage of less than 1 wk, 3 wk, and 6 wk. Survival was measured in mid-June after planting, and after 1 and 4 yr in the field. Total height was measured after 4 yr. The fungicide application increased survival of both species lifted in December or February and was beneficial to longleaf pine seedlings regardless of storage duration. Fungicide-treated longleaf pine seedlings had greater mean 4 yr height than the controls, but fungicides did not affect the height of loblolly pine. South. J. Appl. For. 20(1): 5-9.

Chemical Control of Rhizoctonia Seedling Blight of Longleaf Pine

Abstract Benomyl, chlorothalonil, benodanil, triadimefon, diniconazole, terbuconazole, SN-84364 (Nor-Am experimental) and RH-3486 (Rohm &amp; Haas experimental) effectively inhibited growth of Rhizoctonia sp. isolates from longleaf pine (Pinus palustris Mill.) seedlings when incorporated in agar medium. All fungicides were effective at concentrations as low as 1 μg ai/ml. However, disease incidence was not affected by diniconazole, benodanil or SN-84364 at concentrations of 140 or 280 g ai/ha in a preliminary field trial, and diniconazole exhibited phytotoxic effects on longleaf pine seedlings. Triadimefon at 280 g ai/ha was not effective in controlling longleaf pine seedling blight in an operational field study. SN-84364 at 560 g ai/ha applied every 2 wk reduced disease incidence compared to an untreated control in spring-sown longleaf pine at one nursery, but was not significantly different from the nursery's standard disease management practice of benomyl and chlorothalonil. The nursery where longleaf seed were spring-sown had a significantly greater incidence of longleaf pine seedling blight than nurseries where seed were fall-sown. At one nursery, disease incidence was significantly lower in a bed of fall-sown longleaf pine seedlings than in an adjacent bed of spring-sown seedlings. South. J. Appl. For. 18(1):5-9.

Effects of Viterra® Root Dips and Benomyl on Root Growth Potential and Survival of Longleaf Pine Seedlings

Abstract A mixture of clay and benomyl is registered for use on longleaf pine (Pinus palustris Mill.) to control diseases and increase outplanting survival. However, for one sandy site in Alabama, treating roots with a gel slurry of Viterra containing benomyl reduced survival of stored seedlings when compared to a clay slurry containing benomyl (2.5% active ingredient). Root growth potential for January-lifted seedlings was also reduced by adding benomyl to a Viterra gel. For this study, seedlings planted in January and mid-February had better survival than seedlings planted in December or March. Poor survival in December resulted when seedlings were planted 2 wk prior to a hard freeze. South. J. Appl. For. 18(1):19-23.

Impacts of Feral Hogs on Longleaf Pine Regeneration

Abstract Moderate to heavy populations of feral hogs (Sus scrofa domesticus) were fenced out of 32 tenth-acre plots in a natural regeneration area for longleaf pine (Pinus palustris Mill.) After two growing seasons the fenced areas contained the equivalent of 500 fire-resistant longleaf pineseedlings per acre while corresponding unfenced areas contained only 8 fire-resistant seedlings per acre. Thus free ranging feral hogs caused a crop failure in these natural regeneration stands of longleaf pine. There was evidence that feral hogs selected the larger seedlings. Thus longleafpine seedling crops that survive feral hog depredation will be progressively less competitive and vigorous. Areas with feral hog problems may need to control the hog population by trapping, hunting, or fencing. South. J. Appl. For. 13(4):177-181.

Benomyl Root Treatment Controls Brown-Spot Disease on Longleaf Pine in the Southern United States

Abstract Root systems of longleaf pine seedlings, Pinus palustris Mill., were wetted and then coated with various benomyl/kaolin (clay) mixtures (0 to 20 percent a.i. benomyl) prior to seedlings being outplanted on sites in Louisiana, Mississippi, Alabama, Georgia, and Florida. Survival, percent brown-spot needle blight infection (caused by Scirrhia acicola (Dearn.) Siggers), and growth were evaluated annually for 3 years following planting. Seedling survival generally decreased in a west to east gradient. Survival also decreased with increased benomyl levels at all sites. Interactions of survival and levels of benomyl with measured soil properties were investigated. For increased benomyl levels there was a negative correlation of survival with increased percentage of sand in the soil and a positive correlation of survival with increased levels of silt in the soil. Benomyl root treatments provided effective brown-spot disease control during the 3-year period, which in turn stimulated rapid height growth. A 5 percent a.i. benomyl/kaolin mixture is recommended for root treatment over the natural range of longleaf pine in the southern United States. Forest Sci. 32:506-511.

Planted Longleaf Pine Seedlings Respond to Herbaceous Weed Control Using Herbicides

Abstract Height initiation, and height and diameter growth of longleaf pine (Pinus palustris) seedlings were compared on plots receiving herbaceous weed control treatments and on unweeded check plots during the first 4 years after planting. Treatments initiated during the spring following planting included: broadcast weed control for 1 and 2 years, banded weed control in 5-foot bands for 1 and 2 years, and no weed control (check). Weed control had a positive effect on fourth-year height, groundline diameter, and the percentage of seedlings out of the grass stage, while survival was unaffected. The duration of weed control (2 years vs 1 year) had a similar effect on the same response variables, while the method of weed control (broadcast vs. band) had no effect. Trees on plots receiving 2 years of weed control were approximately 3 feet taller and 0.5 inch greater in groundline diameter than trees receiving no weed control. One year of weed control resulted in trees approximately 2 feet taller and 0.3 inch greater in groundline diameter than with no weed control. Weed control treatments shortened the time seedlings were in the grass stage by approximately 1 year, decreasing the time period during which a serious brown-spot needle blight infection could develop.¹

Pensacola Bahiagrass Can Be Used to Improve the Forage Resource when Regenerating Southern Pines

Abstract Many native forage plants in the South are low quality, poor producers, and unpalatable to cattle. Replacement of these plants with more desirable species would improve the forage resource. One approach is to seed grasses during site preparation when regenerating southern pines. Following site preparation by shearing and strip-disking, Pensacola bahiagrass (Paspalum notatum) was seeded at 15 pounds per acre in the spring and longleaf pine (Pinus palustris) was row-seeded on 12-foot centers in December of the next year. The bahiagrass became established among the residual native plants and was heavily utilized by cattle grazing yearlong. A light application of fertilizer after 3 years tripled bahiagrass yields the first year and doubled it the next year compared to unfertilized plots. Fertilizer improved some nutritional qualities of bahiagrass but digestibility was lowered. Longleaf pine seedlings came out of the grass stage more rapidly and were 50% taller at age 9 with grazing than without it; and in spite of heavier mortality with grazing (36% vs. 21%), stocking was 967 trees per acre at age 11.

Timing of Longleaf Pine Seedling Release from Overtopping Hardwoods: A Look 30 Years Later

Abstract Significant differences in longleaf pine (Pinus palustris) growth among early and delayed seedling release treatments were recorded at age 10, but these differences had disappeared upon reexamination at age 31. A study begun in 1949 included six release treatments: complete seedling release from overtopping hardwoods at ages 1, 2, 3, 4, and 8 years, plus an unreleased check. Treatments were randomly applied among six 0.1-acre plots in each of six blocks, which included both poor and average sites. Seedling development was observed through age 10. When pines in five surviving blocks (two poor site, three average site) were remeasured in 1979 at age 31, there were no significant differences among release treatments in average tree heights and diameters or stand basal areas and volumes. The check treatment had significantly lower tree heights, stand densities, and stand volumes than any release treatment.

May Burning Favors Survival and Early Height Growth of Longleaf Pine Seedlings

Abstract After seven annual May burns, grass-stage longleaf pine (Pinus palustris Mill.) seedling survival averaged 71 percent, significantly higher than survival on a biennial May burn, an annual or biennial March burn, or an unburned control. Seedling height growth on the annual May burn was no better than that on the biennial May burn, but both May burns significantly exceeded the other treatments in height growth. The annual May burn also provided greatest survival and growth for longleaf seedlings that had begun height growth before the study began.

The Effects of Benomyl and Pisolithus Tinctorius Ectomycorrhizae on Survival and Growth of Longleaf Pine Seedlings

Abstract Benomyl applied to roots of longleaf pine (Pinus palustris Mill.) seedlings at planting significantly reduced brown-spot disease and increased survival, root collar diameter, and early height growth on two sites in Mississippi. Seedlings with half or more of all ectomycorrhizae formed by Pisolithus tinctorius (Pers.) Coker and Couch in the nursery had significantly better survival and growth; Pisolithus ectomycorrhizae did not appreciably affect brown-spot disease. The benefits of benomyl and Pisolithus ectomycorrhizae were most obvious when combined. More than 75 percent of seedlings treated with benomyl and with more than half of all ectomycorrhizae formed by Pisolithus initiated height growth after 3 years. Forty-seven percent of seedlings with only Thelephora terrestris ectomycorrhizae and without benomyl exhibited height growth. The combined use of benomyl to control brown-spot disease and Pisolithus ectomycorrhizae to stimulate early height growth may overcome the major handicaps that have limited artificial regeneration of longleaf pine in the South.

Stocking Percent and Seedlings Per Acre in Naturally Established Longleaf Pine

Abstract A relationship between milacre stocking and number of longleaf pine seedlings (Pinus palustris Mill.) per acre was derived from observations of 128 populations naturally established under a wide range of site conditions. The nonlinear regression obtained from the data was Y = 100 [1-(0.561)X], in which Y is the percentage of milacres stocked and X the average number of seedlings per milacre plot (seedlings per acre in thousands). This regression accounted for 85 percent of the observed variation in milacre stocking. The coefficient decreased when sample plot size was reduced to 0.5 and 0.25 milacre.

Interactions of Gamma Radiation and Other Environmental Stresses Upon Pine Seeds and Seedlings

Abstract This is a pilot study to determine the effects of ionizing radiation upon slash (Pinus elliottii) and longleaf (Pinus palustris) pine seeds and seedlings, and to identify environmental factors which modify species radiation sensitivities. Seeds and seedlings were exposed to several radiation doses and then grown in a variety of post-irradiation environments, some of which included high temperature, low moisture and low light. Per cent germination, growth, physiological tolerances, and survival usually varied inversely with the radiation dose received. Germination rates, drought tolerances, and growth under low light intensities were increased by doses in the range of 100–500 R. Slash seeds were more sensitive than longleaf seeds but the order of seedling sensitivity was reversed. Results of this study indicate that the condition of the organism and the nature of the environment prior to and following irradiation must be rigorously defined in order to evaluate radiation effects.

Chemical Control of Undesirable Southern Hardwoods

C ONTROL of low-value or undesirable hardwoods is a problem throughout the forested South, just as brush control is a major need on much of the western range. From eastern Texas and Oklahoma to Virginia, scrub oaks and other weed trees reduce the forage and complicate the management of ranges and pastures. They are equally troublesome in management of forests and maintenance of rightsof-way. After several years of research, the Southern Forest Experiment Station has recently released recommendations for poisoning these low-value hardwoods (Peevy, 1949). Ammonium sulfamate, commercially known as Ammate, is the principal chemical recommended. Four methods of applying Ammate have proven useful in actual tree-poisoning operations: 1. Ammate crystals in cups or notches chopped in base of tree trunk (Figure 1A). This method is recommended for use in standing timber less than 12 inches d.b.h., where complete crown kill with least basal sprouting is desired. It is useful in conversion of low-value hardwood stands to range or pasture, and for timber stand improvement with slow starting longleaf pine seedlings. 2. Solution of Ammate in frills chopped around the tree trunk at convenient height-24 to 30 inches above ground (Figure 1B). This method is suggested where moderate sprouting is permissible, as in range or pasture development, partitularly when subsequent spraying of basal sprouts is feasible. It is also useful in timber stand improvement to release desirable trees at least one or two feet high. It works better than the cup method for trees over 12 inches in diameter. 3. Poisoning freshly cut stumps. The tree is cut and Ammate crystals are applied to the outer sapwood of the stump top. This is useful in clearing land with a minimum of resprouting. 4. Spraying Ammate solution on small trees, brush, and sprouts. Follow-up treatment usually is necessary if complete control is desired. There are conditions under which other chemicals than Ammate should be used; and concentration should be adapted to the method of application as well as species and size of trees to be poisoned. It is the purpose of this article to summarize the experimental results on which these recommendations are based, including choice of chemical, methods and seasons of application, species susceptibility, and costs. The main studies were started in 1944 in central Louisiana on blackjack oak, but the methods have since been tested both experimentally and in scrub hardwood control operations on many tree species in east Texas, Arkansas, Mississippi, Alabama, and elsewhere.