Research Items (94)
- Mar 2014
The mention of grasslands in the United States brings to mind the ecosystems of the Great Plains or high plains of the West. Yet, the eminent ecologist and conservationist Reed Noss reminds us in his book Forgotten Grasslands of the South: Natural History and Conservation that grasslands once occurred across the entire South. These grasslands were larger and more biologically diverse than those of any other region of the country. Where are these grasslands, are they lost and forgotten, or can they be rediscovered and conserved? These are issues that Noss addresses in a remarkable way. Grasslands are described by Noss as any natural community or ecosystem in which the herbaceous layer is dominated by grasses or other grass-like plants, such as sedges and associated forbs. This does not exclude trees, as long as the tree canopy is not dense enough to shade out the herbaceous understory. Grass land communities are grouped into 5 main types: prairies; grassy balds; savannas and woodlands; barrens, glades, and outcrops; and canebrakes. To provide an understanding of the origin and history of southern grasslands, Noss explains the natural history of grasslands based on the fundamental factors of climate, water, fire, wind, substrate and landform, grazing and browsing herbivores, and large predators. This natural history is based on travelers’ accounts of pre-European settlement, evidence of fossil pollen preserved in various locales, types of plants found in the region, the fossil record of the Ice Age mammals, and actual species present today. Southern grasslands, including the longleaf pine communities, are remarkably species rich with the Coastal Plain alone containing nearly one-third of the flora native to North America. Noss reports they are even more species rich than tropical forests. These grasslands are among the most endangered of the world’s ecosystems, however—largely because they are densely inhabited and highly suitable for agriculture. A concern Noss identifies is that grasslands are seen by some as wholly created by Native American fires rather than as natural ecosystems that are worth maintaining. He believes that some grassland types predate human activity and that lightning-ignited fires were a major natural cause of early fire-dependent ecosystems. Noss is clear in his support for the role of fire in maintaining grasslands. He discusses not only why fires are a healthy part of the ecology of the South and of grasslands in particular but also when fire should be used either as prescribed fire or natural wildfire. He provides an ecological view of southern grasslands by describing visits to many sites across the South. These visits, often with skilled local naturalists, provide an appreciation for how geologic history and its elements have interacted with fire to shape grassland landscapes. The book is clearly written, informative, and thought-provoking. The unusual mix of personal anecdotes, summaries of scientific studies, and natural history provide a passionate defense of the endangered southern grasslands. Noss states that humans will only protect nature that we know, and this book introduces readers to biologically rich, once abundant, but now rare natural ecosystems. In the final chapter, Noss outlines an approach that will gain public support for conserving these areas. Forgotten Grasslands of the South is remarkable in both solid science and solid conservation. The reader comes away with an appreciation and understanding of the history, natural history, and complex ecological interactions of the southern grasslands that inspire dedication to their protection and conservation. This volume is a must-read for those involved in managing, conserving, or who just have an interest in southern ecosystems. Destined to become a classic, the book provides better insight into the development and status of southern ecosystems than anything I have ever read. James P Barnett is an Emeritus Scientist for the USDA Forest Service, Southern Research Station, in Pineville, Louisiana.
- Jun 2012
The Kentucky lady's slipper (Cypripedium kentuckiense C.F. Reed [Orchidaceae]) is a spectacular orchid native to the southeastern US. Although its range includes much of the Southeast, it is rare due to loss of appropriate edaphic and climatic habitats. Efforts to restore this species to the Kisatchie National Forest in Louisiana were initiated by a high school student who located a flowering orchid, pollinated it, and collected a fertile seedpod as a collaborative effort to understand the reproductive potential of the species. Results from these evaluations are inconclusive and must be considered preliminary. Additional studies are planned to develop protocols that will facilitate the production of Kentucky lady's slipper orchids on a scale that will allow significant reintroductions of the rare orchid to the Kisatchie National Forest.
Container longleaf pine (Pinus palustris) seedlings often survive and grow better after outplanting than bareroot seedlings. Because of this, most longleaf pine are now produced in containers. Little is known about nursery fertilization effects on the quality of container longleaf pine seedlings and how that influences outplanting performance. We compared various fertilization rates (0.5, 1, 2, 3, or 4mg nitrogen (N) per week for 20weeks) for two crops (2004 and 2005) of container longleaf pine, grown inside a fully-controlled greenhouse (2004 and 2005) or in an outdoor compound (2005). Seedlings grew larger in the nursery with increasing amounts of N. After 20weeks of fertilizer treatment, seedlings received two additional fertigations at the same treatment rate to promote hardening, N concentrations declined sharply, and seedlings shifted biomass production toward roots. Overall, shoots showed more plasticity to N rate than did roots. Survival of either crop after outplanting was unaffected by nursery N rate. For both crops, no seedlings emerged from the grass stage during the first year after outplanting, and during the second year, more seedlings exited the grass stage and were taller as N rate increased up to 3mg per week. By the third field season, nearly all seedlings in the 2004 crop had exited the grass stage, whereas 44% of 2005 crop grown at 1mgN had yet to initiate height growth, either because of differences in seed source between the two crop years or because of droughty conditions. Our data suggests that an application rate of about 3mgN per week for 20weeks plus two additional applications during hardening yields satisfactory nursery growth as well as field response for the container type we used. The potential for improving field performance by using more robust fall fertilization during nursery production should be investigated.
A field study compared genetically improved, container loblolly pines (Pinustaeda L.) with naturally seeded loblolly pines through eight growing seasons on a cutover site in southern Arkansas, U.S.A. Measurement pines on 6 of 12 plots were released from woody and herbaceous competition within a 61-cm radius of each tree stem. On natural pine plots, only 1st-year pine seedlings were selected for measurement based on quality standards and their spacing. Woody competition was controlled by hand cutting for 5 consecutive years, and herbaceous competition was controlled with herbicides for 4 consecutive years. Release treatments increased 8-year survival by 50% for natural pines and by 35% for planted pines. Greater gains (343–391%) in individual tree volumes were achieved within regeneration techniques, as a result of release, than were achieved with the two regeneration techniques. In addition, stand volume gains of 647% and 910% were achieved by planted and natural pines, respectively, as a result of release. Eight years after field establishment, stand volume index averaged 46% higher on planted plots than on natural plots. Degree of overtopping was a better predictor of pine performance than live-crown ratio.
The rate and percent of dark germination were low in untreated Pinustaeda L. seeds. Both increased with seedcoat clipping or removal, but not to the level of stratified seeds. Coats did not reduce the rate of initial water inhibition but did limit total uptake prior to germination, probably by restricting swelling of the megagametophyte and embryo. Respiration followed the pattern of water absorption in decoated seeds. However, it was at a common low level in stratified, clipped, and unstratified seeds until germination began, and there seemed to be no causal relation between respiration and coat permeability. Dormancy is likely to be the result of mechanical constraint by the seedcoat.
The data suggest that constraint by the coat and megagametophyte was an important cause of slowness in southern pine (Pinus spp.) seed germination. As much as 69% of the variation in the speed of germination in five pine species was related to percentage coat weight among the three physical criteria measured. The validity of the constraint concept was supported by higher rates of water and oxygen uptake, increased size of megagametophytes during imbibition, and faster speed of germination of decoated seeds.
General equations for predicting number of blank cells, number of excess seedlings to be thinned, and number of plantable seedlings after thinning were developed for containerized seedling operations. The binomial model which is employed in the prediction equations was tested with germination and survival data from Pinustaeda L. It was concluded that the binomial model satisfactorily represents the germination and survival process in containers for Pinustaeda L. provided the containers do not differ significantly from those used in this study. The effect of thinning Pinuspalustris Mill, seedlings in containers was studied. It was concluded that thinning had a negligible effect on the remaining seedlings and that prediction equations needed no adjustment for thinning mortality.
Choosing a container sowing strategy was formulated as a linear programming problem. The independent variables are fractions of containers seeded to one, two, and three seeds. An optimal sowing strategy is achieved by choosing, subject to certain constraints, the three fractions to minimize an economic penalty function, which penalizes a sowing strategy if it does not deal effectively with problems caused by blank cells. Two options were considered for producing a required number of seedlings with a given number of containers. With option 1 strategies, the three fractions of containers must be chosen so that the predicted number of plantable seedlings cannot be less than the required number, but no provision is made for replanting blank cells. Option 2 strategies have the same constraint that the predicted number of blank cells cannot exceed the predicted number of excess seedlings. Numerical analyses were conducted with hypothetical container sowing problems using estimated costs for procuring and sowing seeds, for carrying or replanting blank cells, and for thinning excess seedlings. Linear programming methods were used to choose a sowing strategy that minimized a penalty function. Mixed sowing strategies, as opposed to the standard strategy of sowing two seeds per cell, were generally optimal for a wide range of values for the germination and survival rate of seeds. A user-oriented, interactive computer program was developed for the nursery manager who wishes to use these methods to choose a sowing strategy.
Seed size was examined as a possible explanation for variation in the size of containerized loblolly pine (Pinustaeda L.) seedlings. Under laboratory conditions of minimal environmental stress, larger seed were found to germinate more quickly and produce a larger germinant after 28 days of growth. In a similar experiment conducted under greenhouse growing conditions, large seed produced the largest seedlings. Size differences among seedlings in both experiments resulted from differences in the rate of germination unique to each seed size class. Consequently, seedling size and possibly uniformity of growth were considered to be a function of germination patterns which were strongly influenced by seed size and weight.
Few studies have examined the combined effects of nutrition and water exclusion on the canopy physiology of mature loblolly pine (Pinus taeda L.). Understanding the impacts of forest management on plantation productivity requires extensive research on the relationship between silvicultural treatments and environmental constraints to growth. We studied the physiological responses of 18-year-old loblolly pine trees exposed to a combination of fertilization (fertilizer or no fertilizer) and throughfall (normal throughfall or throughfall exclusion). Gas exchange variables were measured in the upper and lower crown between 0900 and 1700 h from May to November in 1999. Needle fall was collected to estimate foliage mass and leaf area. Summer drought and throughfall exclusion significantly decreased predawn xylem pressure potential. Needle-level photosynthesis, transpiration, and stomatal conductance declined during the drought and were significantly lower in the throughfall exclusion treatment. Throughfall exclusion also reduced annual foliage mass and daily whole-crown photosynthesis and transpiration. In the normal throughfall treatment, fertilization had no effect on needle-level physiology, but increased annual foliage mass and whole-crown photosynthesis by 26% and 41%, respectively. With the exclusion of throughfall, however, annual foliage mass and daily whole-crown photosynthesis exhibited little response to fertilization. We conclude that greater nutrient availability enhances the carbon uptake of mature loblolly pine trees by stimulating foliage production, but the positive effects of fertilization on leaf area and carbon fixation are limited by low water availability.Key words: foliage mass, photosynthesis, Pinus taeda, seasonal trend, transpiration, xylem pressure potential.
A subset of seedlings from a larger study (Jackson and others 2006, 2007) were selected and evaluated for two growing seasons to relate bud development, and root-collar diameter (RCD), and height growth with three nursery fertilization rates. We chose seedlings in the 0.5 (lowest), 2.0 (mid-range), and 4.0 (highest) mg of nitrogen per seedling treatments. Buds moved through three developmental phases and we confi rmed that when RCD reached 25 mm (1 inch), seedlings were usually ≥ 10 cm (4 inches), had elongated buds, and were exiting the grass stage. After two growing seasons, heights greater than 10 cm (4 inches) were reached on 20, 60, and 65 percent of the 0.5, 2.0, and 4.0-N seedlings, respectively. On average, higher N rates yielded seedlings with larger RCDs, taller heights, and more seedlings exiting the grass stage. On an individual seedling basis, however, we detected a reduction in RCD increment growth with increasing RCD at outplanting across all fertilizer treatments. This phenomenon may be related to root binding, but we have insufficient data to confirm the nature of this response. Further studies are needed to resolve this issue.
Of a range of fertilization rates (0.5, 1.0, 2.0, 3.0, and 4.0 mg nitrogen (N) per seedling per week) applied for 20 weeks, the 2.0-N and 3.0-N seedlings produced good root collar diameter (RCD) growth (6.9 and 7.1 mm, respectively) and needle length ≤ 30 cm. Root collar development did not differ significantly in seedlings receiving the 4.0-mg-N treatment from those receiving 2.0-mg or 3.0-mg, but needles grew to 35 cm in 4.0-N, surpassing the 30-cm limit to avoid clipping. Seedling survival (95 percent) was higher in 3.0-N seedlings one year after outplanting. RCD growth in 3.0-N was 14 percent greater than 2.0-N seedlings, but not different between the 3.0-N and 4.0-N seedlings. Height and RCD growth remained statistically similar between 3.0-N and 4.0-N seedlings after 2 years. Emergence from the grass stage increased as the amount of fertilizer increased, but given similarities in field performance between the two highest N rates, the extra 1.0-mg N per seedling per week was not economically justified.
Production of container longleaf pine (Pinus palustris) seedlings for reforestation and restora-tion plantings exceeds that of bareroot production, but information on container production techniques has been slow to develop. Because success of those outplantings requires quality seedlings, interim guidelines were proposed in 2002 to assist nursery managers and tree planters in developing and using the best stock possible. The guidelines were intended to be updated as new information was generated. During the past 6 years, additional studies have confirmed most provisions of the interim guidelines, except that presence of buds (number and color) as originally described in the guidelines does not appear to be a useful metric. In addition, some new parameters have been added. This report synthesizes that new information and revised guidelines are presented.
- Jan 2007
In lieu of an abstract, here is a brief excerpt of the content: William Cullina previously published 2 well-received and award-winning books that have a focus on native plants—Wildflowers and Native Trees, Shrubs, and Vines. In this book, he returns to an early love of his horticultural career—orchids. Cullina, Director of Horticultural Research at the New England Wild Flower Society, at one time had about 1000 orchids, many of which were collected during trips to South America. Cullina's fascination with orchids is evident. He communicates his appreciation of them through his easy-to-read and conversational writing style. He quickly draws the reader into the fascinating world of orchids. The book is organized in 4 parts: 1) "Setting up the Orchid Environment" covers buying your first orchid, the anatomy of the orchid, where to grow them, light, temperature, humidity and air movement, and detailed information about artificial light; 2) "Care and Feeding" reviews the basics of watering, fertilization, potting and repotting, types of mixture, mounting orchids on trees and branches, pests and diseases, and a troubleshooting guide; 3) "Orchid Reproduction" discusses hand pollination, the care of seedlings, and hybridization; and 4) "Common Orchid Genera from A to Z" features a gallery of orchids with photos and cultural information. In appendixes, information is presented on "Taxonomy and Nomenclature," "Orchids on the Web and Orchid Organizations," and "Judging and Showing Orchids." Although Cullina has written this book for orchid enthusiasts at every level of expertise, from the absolute beginner to experienced grower to expert, I find that it will be of particular value to less experienced growers. As an orchid hobbyist myself, I find the sections on getting started including where to grow orchids, potting and dividing, and controlling pests and diseases of special value. Cullina provides an excellent overview of orchid reproduction with directions for hand pollinating, propagating, and hybridizing. His writing style is friendly, very accessible, with thoughtful, common sense explanations, and the many examples of his personal experiences are encouraging and appreciated. A large portion of the book details the cultural requirements and rates the difficulty level of growing 100 orchid genera of potential interest to growers. Included are recommended growing conditions—window, under lights, or greenhouse—and the level of skill a grower will need to successfully work with a particular genera. Also included for each genus is the native range and number of known species. The level of detail is unusual and of particular value to growers who are looking to expand the types of orchids that are favorable to his or her growing conditions and level of expertise. Although the book is a work of art, printed on high-quality paper with more than 200 excellent photographs, it is much more than a mere coffee-table book. The text is carefully written and full of helpful information on orchid culture, capturing the mental progression of how to go from owning one plant to a whole collection. Cullina is extremely well versed in his subject and is a skilled writer. Growers will find, however, that even the best recommendations will not work in every situation; successful orchid growing requires an understanding that is developed through trial and error under each specific growing environment. Understanding Orchids is the most clearly written, entertaining, and informative general orchid book that I have found. I highly recommend it for both novice and advanced orchid enthusiasts. James P Barnett is an Emeritus Scientist for the USDA Forest Service Southern Forest Experiment Station in Pineville, Louisiana. He and his wife, Jena, are avid orchid hobbyists. Muse Search Journals This Journal Contents Top ...
In 1935 the 7,500 acre Palustris Experimental Forest was ordained by Congress to provide an area for con- ducting forestry research. However, work was already underway to establish research studies before the area was officially designated as an experimental forest within the boundaries of the Kisatchie National Forest. At the time, much of the region consisted of cutover pine lands that had been habitually burned by humans, grazed by domestic livestock, and subject to large populations of free-roaming feral hogs. These conditions hindered any sort of forest regeneration. "Stump orchards" were a term often used to describe what appeared as a grassland punctuated by remnants of the stumps of the old pines. The hogs could be particu- larly devastating to young longleaf pine seedlings whose roots they prized. The Palustris Experimental Forest was named to recognize longleaf pine (Pinus palustris Mill). Longleaf pine was the dominant component of upland pine forests in the southern United States before widespread clear- ing in the early 1900s. Where 90 million acres of longleaf pine forests were once present, only about 3 per- cent of that land is currently in longleaf pine. Longleaf pine forests are critical to those who desire to restore native plant communities, and are essential for species adapted to the longleaf pine ecosystem, principal among these are red-cockaded woodpecker (Dendroica borealis ) and the gopher tortoise (Gopherus polyphe- mus ). The Palustris Experimental Forest is located on the southern Coastal Plain in central Louisiana. Climate is generally warm and moist; average precipitation is 1465 mm per year, and fairly evenly distrib- uted through the year. Annual average temperature is 22 degrees C.
Of all southern pine seeds, longleaf pine (Pinus palutris Mill.) are the most difficult to collect, process, treat, and store while maintaining good seed quality. As a result, interest in techniques for separating filled dead from live longleaf pine seeds has developed. The good news is that new technologies are becoming available to evaluate seed quality, but the bad news is that they seem to have limited application to longleaf pine. Tests suggest that incubating, drying, and separating, chlorophyll fluorescence, and near infrared techniques do not help improve longleaf pine seed quality. The incubating-drying separating method is inefficacious because variability in the seed coat wing stub affects seed flotation. The chlorophyll fluorescence method measures changes in chlorophyll content as seeds mature or are damaged, but such changes do not seem to occur in pine seeds. The near infrared method seems to offer the best potential. The use of near infrared scanning technologies can determine changes in seed constituents, but we have not been able to determine which measurable seed constituents may change as viability declines.
Comparison of the root system growth and water transport of southern pine species after planting in different root-zone environments is needed to guide decisions regarding when, and what species to plant. Evaluation of how seed source affects root system responses to soil conditions will allow seed sources to be matched to planting conditions. The root growth and hydraulic conductivity of three sources each of shortleaf, loblolly and longleaf pine seedlings were evaluated for 28days in a seedling growth system that simulated the planting environment. Across species, an increase in root-zone temperature alleviated limitations to root growth caused by water stress. In the coldest temperature, longleaf pine maintained a higher hydraulic conductivity compared to shortleaf and loblolly pine. Without water limitation, the root growth and hydraulic conductivity of shortleaf and loblolly pine were superior to that of longleaf pine, but as water availability decreased, the root growth of longleaf pine surpassed that of loblolly pine. Hydraulic conductivities of the seed sources differed, and differences were attributed to either new root growth, or an increase in the efficiency of the root system to transport water.
The USDA Forest Service broke ground on its first nursery in 1902 and since then its nurseries have adapted to many changes in scope and direction: from fire restoration to conservation, to reforestation, and back to restoration. In addition to providing a reliable source of native plant material, they have also been a source of research and technology transfer in seedling production and quality. Today, Forest Service nurseries face difficult times due to sharp declines in reforestation seedling orders, but strive to respond to increased demand for a wide variety of native plants for ecosystem restoration.
Three hardwall container types, one styroblock® container type, and two mesh-covered plugs were used to grow longleaf pine (Pinus palustris Mill.) seedlings at a nursery in Louisiana. In 2001, these container types, along with bare-root seedlings (from a different seed source), were outplanted on two old-field sites and two cutover sites. There were significant site by treatment interactions. Second-year survival was higher on cutover sites than on old-field sites. Root-collar diameter of container-grown stock was positively related to root growth potential (RGP) and height after two growing seasons. Container-grown stock with the lowest RGP exhibited the lowest overall seedling survival. On three sites, field performance of seedlings grown in mesh-covered plugs was less than seedlings grown in other types of containers. For styroblock® trays, treating cell walls with copper increased RGP but did not affect field performance. Increasing the spacing between container cells increased diameter and height after two growing seasons. A root bound index (RBI) was developed and was calculated for each container seedling by dividing root-collar diameter by the diameter of the container cell. Survival was low when RBI was greater than 27%. Although large-diameter bare-root stock can be advantageous as far as survival and growth is concerned, the same may not be true for containers. Some 7-month old container seedlings might become too large for some container types.
Slash pine is the premier tree species on many sites throughout the South. Its ease of establishment and early growth, however, has extended its range to many sites where its performance has been less than ideal. For that reason, the acreage and volume of slash pine are declining. Nonetheless, it will continue to be the favored species on many sites where it is the most appropriate and productive species. This paper reviews slash pine's important silvical characteristics, its history of use and management, and the status and trends of this important resource.
In an operational trial, increasing the amount of nitrogen (N) applied to container longleaf pine seedlings by incorporating controlled release fertilizer (CRF) into the media improved seedling growth and quality. Compared with control seedlings that received 40 mg N, seedlings receiving 66 mg N through CRF supplemented with liquid fertilizer had needles that were 4 in (10 cm) longer as well as 42%, 84%, and 47% greater root collar diameter, shoot biomass, and root biomass, respectively. We use data from this study and other published sources to make general, practical guidelines concerning appropriate levels of fertilization for longleaf pine seedlings in containers.
Nursery managers can improve germination of longleaf pine (Pinus palustris P. Mill. [Pinaceae]) seeds and seedling establishment by reducing seedborne pathogenic fungi with appropriate sterilants and fungicides. We have tested many chemicals, but hydrogen peroxide, thiophanate methyl, and thiram seem to provide the best results in reducing the large populations of microorganisms carried on the large, thin, and fibrous seed coats. Our evaluations of longleaf seeds indicate that Fusarium spp. are major seedborne pathogens that cause mortality to seeds and newly germinated seedlings. Seeds of other southern pines have denser coats and are less adversely affected by the presence of seedborne pathogens. The increased demand for longleaf pine seeds in the last few years makes reducing this contamination an important consideration by seed dealers and nursery managers.
Automated weather stations collected microclimatic data over a 4.75-year period in six reproduction cutting treatments—a clearcut, two shelterwoods, a group selection, a single-tree selection, and an unmanaged control—in shortleaf pine stands in the Ouachita Mountains of west-central Arkansas. Treatment means for air temperature at 15 cm, soil temperature, solar radiation, and windspeed were greater for the clearcut than for the group selection, whereas air temperature at 2 m and vapor pressure deficit were markedly higher for the group selection treatment. A thermal inversion effect might be the cause. Retaining overstory hardwoods in the pine-hardwood shelterwood led to increased vapor pressure and soil moisture deficits vs. the pine shelterwood alone. Solar radiation in the single-tree selection was three times greater than in the unmanaged control. Foresters who employ natural regeneration to meet the landowner's goals should be aware of important microclimatic attributes of reproduction cutting methods at their disposal.
Most container seedlings grown in the southeastern US are outplanted during winter, although 10 to 20% are outplanted during summer. Longleaf pine accounts for more than 80% of all container seedlings produced. Very little information is published on cold hardiness and storage effects on container-grown southern pines and hardwoods. In general, growers attempt to minimize storage time by coordinating extraction with outplanting, particularly during summer outplanting. Seedlings are hand extracted and placed into wax-coated boxes with slits or holes in the sides, either with or without a plastic liner, and placed into cooler storage. Seedlings for summer outplanting are generally stored at 40 to 70 ∞F (4 to 21 ∞C) but usually for a week or less. Seedlings extracted in winter (November through January) are kept at cooler temperatures (35 to 50 ∞F (2 to 10 ∞C)), sometimes for as long as 3 months. Research on cold hardiness development would be helpful in understanding proper storage conditions and lengths for southern pines.
- Sep 2003
To assess the effects of stand density and canopy environment on tree physiology, we measured gas exchange responses of the same needle age class of 16-year-old loblolly pines ( Pinus taeda L.) in thinned (512 trees ha -1) and non-thinned treatment plots (2,863 trees ha -1) in central Louisiana. Physiological data were collected in the upper and lower canopy positions on 26 sunny days between July 1996 and June 1997 (one-half of the leaf life span). Mean net photosynthesis was highest (4.3mol m -2 s -1) in the spring and closely corresponded with light intensity in the canopy. Photosynthesis in the winter was nearly 3.0mol m -2 s -1, indicating that loblolly pine enables substantial carbon fixation all year around in the Gulf Coastal Plain region. Mean transpiration and stomatal conductance were highest in the summer and lowest in the winter. With increased light availability after thinning, needle photosynthesis, transpiration and stomatal conductance rose 84, 40 and 23%, respectively, in the lower canopy of the thinned-treatment trees. Light-saturated photosynthetic capacity of the lower canopy needles was 5.2mol m -2 s -1 for the thinned treatment and 4.2mol m -2 s -1 for the non-thinned treatment. It is concluded that thinning-induced light penetration through the canopy enhances physiological activities in the lower canopy foliage of residual trees, and that light availability is the only significant variable for predicting needle-level photosynthesis rates.
- Jul 2003
Total foliage dry mass and leaf area at the canopy hierarchical level of needle, shoot, branch and crown were measured in 48 trees harvested from a 14-year-old loblolly pine (Pinus taeda L.) plantation, six growing seasons after thinning and fertilization treatments.In the unthinned treatment, upper crown needles were heavier and had more leaf area than lower crown needles. Branch- and crown-level leaf area of the thinned trees increased 91 and 109%, respectively, and whole-crown foliage biomass doubled. The increased crown leaf area was a result of more live branches and foliated shoots and larger branch sizes in the thinned treatment. Branch leaf area increased with increasing crown depth from the top to the mid-crown and decreased towards the base of the crown. Thinning stimulated foliage growth chiefly in the lower crown. At the same crown depth in the lower crown, branch leaf area was greater in the thinned treatment than in the unthinned treatment. Maximum leaf area per branch was located nearly 3–4 m below the top of the crown in the unthinned treatment and 4–5 m in the thinned treatment. Leaf area of the thinned-treatment trees increased 70% in the upper crown and 130% in the lower crown. Fertilization enhanced needle size and leaf area in the upper crown, but had no effect on leaf area and other variables at the shoot, branch and crown level. We conclude that the thinning-induced increase in light penetration within the canopy leads to increased branch size and crown leaf area. However, the branch and crown attributes have little response to fertilization and its interaction with thinning.
Slash pine is a desirable species. It serves many purposes and is well adapted to poorly drained flatwoods and seasonally flooded areas along the lower Coastal Plain of the Southeastern US. The use of high-quality seeds has been shown to produce uniform seedlings for outplanting, which is key to silvicultural success along the Coastal Plain and elsewhere. We present information for nursery managers who collect, process, and treat slash pine seeds.
- Nov 2002
Genetically improved, container loblolly pine (Pinus taeda L.) seedlings were compared to naturally established loblolly seedlings on a cutover pine site. Crop pines on 6 of 12 plots were released from woody and herbaceous competition within a 2 ft radius of each stem. On release plots, woody competition was controlled by hand-cutting for 5 consecutive yr and herbaceous competition was controlled with herbicides for 4 consecutive yr after pine establishment. Competition control increased 12 yr survival by 68 percentage points for natural pines and by 47 percentage points for planted pines. Twelve years after field establishment, mean-tree volume of planted pines was no different than that of naturally established pines. Nevertheless, volume gains of 150% to 200% were achieved within regeneration techniques as a result of release. South. J. Appl. For. 26(4):173180.
Longleaf pine (Pinus palustris Mill.) ecosystems once occupied 90 million acres in the southern United States coastal plain. These firedependent ecosystems dominated a wide range of coastal plain sites, in- cluding dry uplands and low, wet flatlands. Today, less than 4 million acres remain, but these ecosystems represent significant components of the region's cultural heritage, ecological diversity, timber resources, and present essential habitat for many animal and plant communities. This ecosystem is also the favorite habitat for endangered species like the red-cockaded woodpecker and the gopher tortoise. Fire was an essential component of the original longleaf pine ecosystems. The landscapes were characterized by open stands of mature longleaf pine with a savanna-like understory that was biologically diverse. Recent im- provements in the technology to artificially regenerate longleaf pine have stimulated interest in restoring longleaf pine on many sites. Long-term studies show that the frequent use of fire hastens initiation of height growth, reduces undesirable competing vegetation, and stimulates growth and development of the rich understory. Fire is, therefore, an important element in establishing the species and is critical to achieve and maintain the biologically diverse conditions that are characteristic of the ecosystem.
- Apr 2000
Direct seeding is a potential method for reforestation of pines on many southern sites. The success of direct seeding, however, depends, at least in part, in reducing seed predation by birds and rodents. We conducted a series of tests to assess the efficacy of capsicum and thiram in reducing mouse damage to longleaf pine (Pinus palustris) seeds. House mice (Mus musculus) predation was reduced (P<0.05) by treating seeds with either capsicum or thiram or a mixture of the two ingredients. Deer mice (Peromyscus maniculatus) avoided seeds treated with a mixture of capsicum and thiram. We conclude that the capsicum and thiram mixture should be pursued as a potential repellent to protect longleaf pine seeds from animal predation when these seeds are used in direct seeding efforts to establish southern pine forests.
We provide basic guidelines for nursery production of longleaf pine (Pinus palustris 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.
- Jan 2000
Longleaf pine (Pims puhrstrk Mill.) ecosystems once occupied over 36 million hectares in the southeastern United States' lower coastal plain. These fire-dependent ecosystems dominated a wide range of coastal plain sites, including dry uplands and low, wet flatlands. Today, less than 1.3 million hectares remain, but these ecosystems repre- sent significant components of the Region's cultural heritage, ecological diversity, timber resources, and present essential habitat for many animal and plant communities. Fire was an essential component of the original longleaf pine ecosystems. The landscapes were characterized by open stands of mature iongleaf pine with a savanna-like understory that were biologically diverse. Recent improvements in the technology to artificial- ly regenerate longleaf pine has stimulated interest in restoring longleaf pine on many sites. Long-term studies show that the frequent use of fire hastens initiation of height growth, reduces undesirable competing vege- tation, and stimulates growth and development of the rich undcrstory. So, fire is an important element in establishing the species and is critical to achieve and maintain the biologically diverse understory that is charac- teristic of the ecosystem. (Article copies available for a feefiorn The Haworth Document Delivery Service: l-800-342-9678. E-mail address: getitlfo@ haworthpressittc.com c Website: http:llwww.ha wortllpressitlc.conl>)
- Jul 1999
The impacts of thinning, fertilization and crown position on seasonal growth of current-year shoots and foliage were studied in a 13-year-old loblolly pine (Pinus taeda L.) plantation in the sixth post-treatment year (1994). Length of new flushes, and their needle length, leaf area, and oven-dry weight were measured in the upper and lower crown from March through November. Total shoot length was the cumulative length of all flushes on a given shoot and total leaf area per shoot was the sum of leaf areas of the flushes.
To examine physiological responses to thinning, fertilization, and crown position, we measured net photosynthesis (Pn), transpiration (E), vapor pressure difference (VPD), stomatal conductance (gs), and xylem pressure potential (Ψ1) between 0930 and 1130 h under ambient conditions in the upper and lower crowns of a 13-year-old loblolly pine (Pinus taeda L.) plantation six years (1994) after the treatments were applied. Photosynthetic photon flux density (PPFD) and air temperature (Ta) within the canopy were also recorded. Needle Pn of thinned trees was significantly enhanced by 22–54% in the lower crown, because canopy PPFD increased by 28–52%. Lower crown foliage of thinned plots also had higher E and gs than foliage of unthinned plots, but thinning had no effect on needle Ψ1 and predawn xylem pressure potential (0430–0530 h; Ψpd). Tree water status did not limit Pn, E and gs during the late-morning measurements. Fertilization significantly decreased within-canopy PPFD and Ta. Needle Ψ1 was increased in fertilized stands, whereas Pn, E and gs were not significantly altered. Upper crown foliage had significantly greater PPFD, Pn, VPD, gs, E, and more negative Ψ1 than lower crown foliage. In both crown positions, needle Pn was closely related to gs, PPFD and Ta (R2 = 0.77 for the upper crown and 0.82 for the lower crown). We conclude that (1) silvicultural manipulation causes microclimate changes within the crowns of large trees, and (2) needle physiology adjusts to the within-crown environmental conditions.
- Feb 1999
To examine physiological responses to thinning, fertilization, and crown position, we measured net photosynthesis (P-n), transpiration (E), vapor pressure difference (VPD), stomatal conductance (g(s)), and xylem pressure potential (Psi(1)) between 0930 and 1130 h under ambient conditions in the upper and lower crowns of a 13-year-old loblolly pine (Pinus taeda L.) plantation six years (1994) after the treatments were applied. Photosynthetic photon flux density (PPFD) and air temperature (T-a) within the canopy were also recorded. Needle P-n of thinned trees was significantly enhanced by 22-54% in the lower crown, because canopy PPFD increased by 28-52%. Lower crown foliage of thinned plots also had higher E and g(s) than foliage of unthinned plots, but thinning had no effect on needle Psi(1) and predawn xylem pressure potential (0430-0530 h; Psi(pd)) Tree water status did not limit P-n, E and g(s) during the late-morning measurements. Fertilization significantly decreased within-canopy PPFD and T-a. Needle Psi(1) was increased in fertilized stands, whereas P-n, E and g(s) were not significantly altered. Upper crown foliage had significantly greater PPFD, P-n, VPD, g(s), E, and more negative Psi(1) than lower crown foliage. In both crown positions, needle P-n was closely related to g(s), PPFD and T-a (R-2 = 0.77 for the upper crown and 0.82 for the lower crown). We conclude that (1) silvicultural manipulation causes microclimate changes within the crowns of large trees, and (2) needle physiology adjusts to the within-crown environmental conditions.
Longleaf pine (finus pa/u&is Mill.) seeds are sensitive to damage during collection, processing, and storage. Highquality seeds are essential for successful production of nursery crops that meet management goals and perform well in the field. We conducted a series of tests under laboratory and nursery conditions to evaluate what effect a number of presowing treatments, e.g., soaking, stratification, and coat sterilization, had on the performance of longleaf pine seeds of varying qualities. Test results indicate that removal of fungal contamination from the seedcoats will markedly improve seed germination and seedling establishment in the nursery. Both a l-hour soak in 30-percent hydrogen peroxide and a IO-minute drench in a 2.5 percent a.i. per liter benomyl solution improved longleaf pine seedlot performance, particularly in seedlots of low to medium quality. Based on seedling establishment 3 months after sowing, other treatments, which included water soaking and stratification, were less effective than sterilants. Because the benomyl drench was as effective as the hydrogen peroxide soak, it is the preferred treatment for controlling seedcoat contamination: it is both more economical and safer for the nursery manager to use. An effort is underway to extend the registration for this seed treatment to Southern States other than North Carolina, where it is currently labeled.
Longleaf pine (Pinus palustrisMill.) ecosystems once occupied over 36 million hectares in the southeastern United States' lower coastal plain. These fire-dependent ecosystems dominated a wide range of coastal plain sites, including dry uplands and low, wet flatlands. Today, less than 1.3 million hectares remain, but these ecosystems represent significant components of the Region's cultural heritage, ecological diversity, timber resources, and present essential habitat for many animal and plant communities. Fire was an essential component of the original longleaf pine ecosystems. The landscapes were characterized by open stands of mature longleaf pine with a savanna-like understory that were biologically diverse. Recent improvements in the technology to artificially regenerate longleaf pine has stimulated interest in restoring longleaf pine on many sites. Long-term studies show that the frequent use of fire hastens initiation of height growth, reduces undesirable competing vegetation, and stimulates growth and development of the rich understory. So, fire is an important element in establishing the species and is critical to achieve and maintain the biologically diverse understory that is characteristic of the ecosystem.
- Jan 1998
- The Productivity and Sustainability of Southern Forest Ecosystems in a Changing Environment
The gaseous composition of the atmosphere has changed significantly during the past century as the result of anthropogenic activity. Changes in the physical and chemical climate of the southern United States may have significant detrimental effects on the forest tree species that grow in this extensive and complex region. Although the consequences of these changes for forest ecosystems are manifold, the most significant outcomes may be 1) chronic exposure of ecologically and economically important species to elevated levels of phytotoxic pollutants, and 2) global and regional scale changes in precipitation regimes. Knowledge of the combined impacts of the climatic and air pollutant stresses on forests and forest species is essential to ensuring their productivity and sustainability.
- Sep 1997
Physiological parameters were measured under natural light conditions and needle orientation from towers and walkways erected in the canopy of a loblolly pine (Pinus taeda L.) plantation. Four silvicultural treatments were randomly assigned to the twelve plots in the fall of 1988. Plots were thinned to a density of 731 trees per hectare or left unthinned, at a density of 2990 trees per hectare. The plots were left unfertilized or fertilized with 744 kg/ha of diammonium triple superphosphate was applied. During the fifth growing season (1993) following thinning and fertilization, needle level physiology was not different with respect to the thinning treatment for fertilized or unfertilized plots. In contrast, upper crown levels within the fertilized and unfertilized plots had significantly higher light levels and photosynthetic rates than lower crown foliage. Light levels were greater in the thinned, fertilized plots than in the unthinned, fertilized plots. In contrast, no effect of thinning on canopy light levels was found in the unfertilized plots. Within crown variation in photosynthesis was strongly dependent on canopy light levels. A strong interaction of canopy level with thinning was apparent for net photosynthesis. Loblolly pine, being a shade intolerant species, showed only small physiological differences between needles from different parts of the crown. Because of the variability found in this study, more extensive sampling is needed to correctly describe the physiology of a forest canopy with adequate precision.
- Oct 1996
Tree improvement programs have influenced significantly the quality of southern pine seeds produced when compared to collections from native stands. Seed orchard management practices such as fertilization can increase seed size and reduce seed dormancy. These result in the need for less complex pregermination treatments. Repeated cone collections from the same clones facilitate collections according to ripening (cone specific gravity), which can improve seed germination and storage. However, cultural practices may result in seed properties that are more sensitive to damage during processing procedures and result in lower quality unless special care is provided during this stage of handling. The effect of orchard management practices on seed quality also varies by species, with loblolly pine being less affected than longleaf pine.
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.
Loblolly pines (Pinus taeda L.) that were 8 to 17 yr old tolerated one to three fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shiraif sp. fusiforme) galls in their stems. Families with four or more galls in their stems lost 25% or more of the trees by age 17. In living trees with less than four stem galls, diameter growth was comparable to that of trees with no galls. Tolerance was indicated by the ability of loblolly pines to maintain the rust fungus in stems that had dbh's similarto asymptomatic trees on the same site. In plantations, the number of galls in the stem was generally one to two per infected tree. This was also true for mature trees (12 to 38 in. dbh) along the Natchez Trace Parkway. These trees have been infected with fusiform rust for nearly 100 yr. On the other hand, the presence of four or more stem galls seems to be a reliable indicator of mortality rather than tolerance. South. J. Applied For. 19 (2): 60-64.
- Apr 1994
A field study compared genetically improved, container-grown loblolly pine (Pinus taeda L.) seedlings to naturally established loblolly seedlings on a cutover pine site in southern Arkansas, USA. Pines on 50% of all plots were released from woody and herbaceous competition within a 61 cm radius of each tree stem. Woody competition was controlled by hand cutting for 5 consecutive years and herbaceous competition was controlled with herbicides (sulfometuron methyl and glyphosate) for 4 consecutive years. Competition control increased 5-year survival by 21–23% for natural and planted seedlings, respectively, with no statistically significant difference between the two regeneration techniques. Five years after field establishment, planted pines averaged 85% more volume than naturally established pines. Nevertheless, greater volume gains (551–688%) were achieved within regeneration techniques, as a result of competition control, than were achieved between the two regeneration techniques.
Longleaf pine (Pinus palustris Mill.) is the most difficult of the southern pines to regenerate by artificial means. One of the basic concerns in regenerating longleaf pine has been in obtaining, processing, and storing seeds of good quality. High seed quality is essential for successful regeneration of the species by either direct seeding or planting. Recommendations for producing and maintaining seed quality at a level equivalent to seeds of the other southern pines are developed in this article. Southern J. Appl. For. 17(4): 180-187.
Although longleaf pine (Pinus palustris Mill.) seeds are considered the most susceptible of the southern pines to damage during collection, processing, and storage, results of these studies show that high seed quality can be assured for periods up to 20 yr through proper handling and storing techniques. Recommendations for long-term storage include drying seeds to moisture contents of 10% or less and storing at subfreezing temperatures, preferably near 0°F. Reevaluation of stratification treatments applied under operational conditions indicates that the soaking in water that is necessary for seed imbibition reduces total germination in an amount proportional to the length of the soak. Stratification is not recommended except under very controlled conditions. South. J. Appl. For. 17(4):174-179.
The performance of container and bareroot loblolly pine (Pinus taeda L.) seedlings from the same improved seedlot was compared on highly productive bottomland sites in South Carolina. At the time of planting, size and quality of the open-grown container stock were equal to or better than bareroot material. When outplanting conditions were ideal, field plantings in March, April, and May of 2 successive years indicated equal performance of the 2 stock types. When conditions were more stressful, container stock survived and grew better than bareroot seedlings. Needle-tip burn caused by postplanting applications of herbicides had no long-term effects on seedling growth. South. J. Appl. For. 17(2):80-83.
- Nov 1991
Four open-pollinated families of shortleaf pine (Pinus echinata Mill.) seedlings were planted near Perryville, AR, in February 1988. Three herbaceous weed control treatments were tested for each family along with an untreated check. A single treatment of 3 oz ai/ac of Oust® was applied in April 1988 for spot, band, and total control of herbs. Total control was maintained with directed applications of Roundup° (3% product) as needed. Seedling survival averaged above 95% after two growing seasons for each treatment. Soil moisture, seedling growth, and seedling biomass were greatest and fascicle water potential of pines was least negative on plots receiving total control of herbs. Intermediate levels of fascicle water potentials occurred in spot- and band-treated plots where seedlings realized 91% of the height and 83% of the diameter growth potential for the site. Lowest soil moisture and growth plus most negative fascicle water potentials occurred on untreated check plots. Families differed in their physiological response when soil moisture increased. Needles and roots were the largest components of biomass. While improving pine growth, spot treatments for herbaceous weed control offer ecological and cost advantages over band treatments or total control. South. J. Appl. For. 15(4):199-204.
- Jan 1991
- Forest Regeneration Manual
Container southern pine seedlings offer an alternative to bareroot stock, especially when short production times are required, the planting season is to be extended, or adverse sites are to be planted. Acceptable container seedlings can be produced under various degrees of environmental control and in several container types. However, seedling quality depends on the quality of the seeds sown and proper use and timing of cultural practices, especially sowing techniques, growing-medium moisture, and seedling nutrition. Shoot and root morphology can be controlled when seedlings are grown in containers to produce stock of desired characteristics for outplanting under specified conditions. Handling and planting methods used with container southern pines depend on the time of year and physiological condition of the seedlings.
- Mar 1990
When combining pines and cattle on tame pasture, grazing is often delayed for several years until trees are large enough to resist injury. As an alternative approach to delayed or deferred grazing during the early years, this study in central Louisiana, USA, examined the effects of cattle grazing in subterranean clover (Trifolium subterraneum L.) pastures on slash (Pinus elliottii Engelm.) and loblolly pine (P. taeda L.) seeding survival and growth during the first 3 years of tree establishment. Pines were planted at about 1200 trees/ha in 3 rows on 0.4-ha subclover units with 1.3 m spacing within rows. Three grazing treatments included: (1) ungrazed pines, (2) limited grazing with a single-wire electric fence above the planted pines, and (3) grazed pines. Thirty Brahman crossbred cows with calves and a bull grazed the tame pasture on a controlled grazing, rotational basis from December through May each year, during the subterranean clover growing season. Pine trampling injury during the year was 8% on the grazed seedlings while essentially none occured under limited grazing. During the first 2 growing seasons, survival and height of the pines were significantly less on the grazed seedlings than on either the limited grazing or ungrazed seedlings. Pine heights from the limited grazing and ungrazed treatments were not different during the 3-year study; loblolly pine heights from the limited grazing treatment continued to be taller than the grazed treatment through the third year while the slash pine heights were similar for all treatments by the third year. Seedling mortality became more acute as severity of grazing injury increased; the greatest mortality occured when the terminal bud and needles were both browsed off.
- Nov 1988
Field survival of longleaf, shortleaf, slash, and loblolly pine seedlings that had benomyl incorporated into the packing medium was markedly improved over that of clay-slurry controls. The more difficult to store seedlings of longleaf and shortleaf pine had greater magnitudes of response than more easily stored loblolly and slash pines. The decrease in seedling survival with storage time is related to a rapid increase in pathogenic microorganisms in cold storage. Although Benlate® ¹ 50WP is now registered for this use, the most effective fungicide dosage rates for routine use with different southern pine species must still be determined. South. J. Appl. For. 12(4):281-285.
- Sep 1988
Tests over a 4-year period with eastern white pine in western North Carolina indicated that cone and seed maturity could not be accurately determined by specific gravity, but cone moisture content appeared to be directly related to both. A moisture content of 200% (dry weight basis) indicated maturity of both cones and seeds. After-ripening of cones for 4 weeks improved both seed yield and quality. Moist cone storage was helpful only if immature cones were collected. Dry cone storage provided seeds of high viability over the entire collection period. North. J. Appl. For. 5:172-176, Sept. 1988.
- Mar 1986
The survival of bare-root and container-grown loblolly pine (Pinus taeda L.) seedlings exceeded 90% when outplanted in March at two sites in Lee County, Alabama. At both sites, soil moisture and seedling survival were greater in March than in May. A March herbicide application reduced weed biomass by 75–80% at both sites. At the moist site, herbicide application did not affect survival. However, at the drier site, a reduction in weed biomass increased both the percent soil moisture and the survival of May-planted bare-root seedlings. When soil moisture at planting time was less than 13% on a dry weight basis container-grown seedlings survived better than bare-root seedlings. At both sites, reduced weed competition resulted in greater seedling heights and diameters.
- Jun 1985
Viability of slash and shortleaf pine seeds was 66 and 25 percent, respectively, after 50 years of cold storage. Evaluations of leachate conductance, chromosomal aberrations, and seedling development indicated some loss of vigor over the storage period, but probably not enough to affect adversely the genetic makeup of the next generation. Forest Sci. 31:316-320.
- Aug 1984
Although they are not fully satisfactory, laboratory germination percentages are still better predictors of nursery-tree yield for both loblolly (Pinus taeda L.) and slash (Pinus elliottii Engelm.) pine seeds than any other means now available. Germination values, which combine both speed and completeness of germination, improve the predictability of nursery performance only in slowly germinating lots. Analyses of the reasons for better nursery growth of seedlings from stratified seeds reveal that under less favorable conditions they germinate faster than unstratified seeds. When equal-aged germinants from similarly-sized stratified and unstratified seeds are planted at the same time, seedling development is essentially the same. Seedlings from large-sized seeds (half-sib lots) did grow larger over a 10-week period than those from small-sized seeds.
Temperature and available moisture are environmental variables with substantial control over seed germination. Speed and completeness of germination in loblolly pine (Pinus taeda) seed strongly influence seedling yields. The impact of moisture and temperature on loblolly seed performance was investigated by germinating seed at temperatures cycling between optimal (21°C) and stressful (13°C or 35°C) or in the presence of osmotically simulated moisture stress ranging between -300 kPa and -1500 kPa. The rate of germination was significantly reduced by exposure to the low temperature treatment. Any level of osmotically induced moisture stress decreased the rate and, ultimately, total germination. The impact of temperature or moisture stress was partially mitigated by increasing the stratification interval prior to germination. Consequently, low temperatures and/or decreased availability of moisture represent potential environmental restrictions on crop establishment and subsequent seedling yields. Germination patterns of seed experiencing environmental stress can be improved by extending the interval of stratification prior to sowing.
A variety of physiological and morphological characteristics of container grown southern pine seedlings were measured at the time of outplanting and then related to field performance. The variables measured included: needle chlorophyll content, degree of mycorrhizal inoculation, biochemical constituents, seedling height and stem diameter, dry weight of roots and shoots, and shoot/root ratios. Although many of the variables were significantly correlated to one another, seedling heights were most positively related to growth in the field. Most of the characteristics measured could not be closely related to field survival, because survival was unusually high. Cultural treatments applied during the greenhouse growing period affected both initial seedling development and field performance.
- Dec 1983
The mechanism of germination enhancement by cold stratification was examined in seeds of loblolly pine (Pinus taeda L.), Removal of the seed coat permitted elongation of radicles from unstratified embryos, but both rates of germination and radicle elongation were increased by stratification. Radicles of both stratified and unstratified embryos excised from the megagamethophyte elongated only when in contact with solid incubation media supplemented with sucrose. Stratification of embryos either in the presence or absence of the megagametophyte resulted in similar enhancement of radicle elongation. Elongation rates of radicles were increased after stratification independent of sucrose concentration, and changes in sucrose content in the megagamethophyte during stratification or incubations subsequent to stratification were insufficient to regulate radicle growth. Our results support the hypothesis that the embryos of pine seeds perceive the low temperature stimulus directly and this stimulus results in a growth potential increase in the embryonic axes. We propose that this growth potential increase enables the embryos to overcome the mechanical restraint of the seeds coats and to germinate.
- Jan 1983
Use of container-grown seedlings will increase, but they will remain a supplement to bare-root production. -R.H.Johnson
- May 1982
Sorting of a bulked loblolly pine (Pinus taeda L.) orchard seed lot into four different size classes did not result in seedlings from any one class having a consistent growth advantage. Larger seeds displayed the lowest total germination but yielded as large or larger containerized seedlings 12 weeks after sowing. Seed size had no effect on field survival. Total height and height growth over a three-year period in the field were not consistently affected by seed size, although large seeds tended to yield slower-growing seedlings. Uniformity in sowing and subsequent uniformity in growing space seems to be the major justification for sizing loblolly seeds for containerized seedling operations.
- Feb 1981
Bare-root and container-grown shortleaf pine (Pinus echinata Mill.) seedlings with Pisolithus tinctorius and Thelephora terrestris ectomycorrhizae were outplanted on two reforestation sites on the Ouachita National Forest. On the better site, survival and growth of containerized seedlings were better than that of bare-root seedlings. On the poorer site, the reverse was true. Mycorrhizal treatment provided no consistent advantage for survival and growth for containerized seedlings. However, bare-root seedlings with half or more of their ectomycorrhizae formed by P. tinctorius before planting had greater survival and growth on both sites than seedlings with lesser amounts of Pisolithus ectomycorrhizae. The difference in mycorrhizal treatments among containerized and bareroot seedlings are discussed.
SUMMARY Container-grown shortleaf pine (Pinus echinata Mill.) seedlings inoculated with Pisolithus tinctorius and drenched with benomyl formed more mycorrhi- zal roots than undrenched seedlings. Seedlings were drenched (2.5, 5, and 10 mg ai in 15 ml of water per individual) prior to sowing and at either 2-, 4-, or 8-week intervals. Pisolithus formed best at the highest benomyl level, 10 mg every 2 weeks. Beno- myl application increased seedling diameter, height, and weight. Highest benomyl dosages produced the largest seedlings.
Peak germination of unstratified longleaf, short-leaf, loblolly, and slash pine seeds occurred at 75° F. Longleaf seeds germinated better at lower temperatures and less successfully at higher temperatures than those of slash, loblolly, and shortleaf pine. Stratification broadened the range at which slash, loblolly, and shortleaf germinated satisfactorily. Improvement in germination was greater at temperatures below 75° than above 75° Temperatures of 95° resulted in low germination under all conditions.
Costs of producing container-grown seedlings increase when containers are not fully stocked. Best use of containers requires high seed viability and low losses of newly germinated seedlings. Seed handling practices before and after sowing affect germination and seedling survival. This is a summary of seed preparation, sowing rates, disease control, and seed germination for container-grown southern pines.
- Mar 1971
Flotation in ethanol to separate full and empty seeds of spruce pine and slash pine caused viability to decline in storage. Drying for extended periods after the soaks alleviated some of this effect. Flotation of longleaf pine seeds in pentane did not affect storability. Forest Sci. 17: 50-51.
- Sep 1970
Respiratory quotients for longleaf pine (Pinus palustris Mill.) seeds were generally lower than for slash pine (P. elliottii Engelm.). The values for longleaf pine peaked when the radicle emerged. Changes in lipid and soluble-sugar contents of longleaf pine seeds indicate that the rise in respiratory quotients reflected a change in respiratory substrate from lipids to sugars when the radicle emerged. Before germination started, protein contents of seeds of the two species were almost identical. During the first 10 days of germination and seedling development, protein levels in slash pine increased in all seed parts faster than those in longleaf pine. The differences in respiratory activity and nitrogen metabolism between the two species indicate that their metabolic pathways were differentially used during germination and early seedling development. Forest Sci. 16:350-355.
- Jan 1970
Viability of seeds of all southern pine species can be maintained long enough for practical needs. Control of moisture content and temperature is of primary importance in prolonging viability, but cone maturity, time from harvest to extraction, and seed extracting and processing techniques are also influential.
The vast harvest of the native forests of the South in the 19 th and early 20 th centuries created a great need for reforestation and silvicultural knowledge. An emphasis on forestry research that changed the face of the South began with the establishment of the Southern and Appalachian Forest Experiment Stations in 1921. Working under primitive conditions, early researchers provided the information that was used to restore the southern forests. A key to this success was the interaction and cooperation of workers in universities, State service, Federal service, and forest industry.
Longleaf pine (Pinus patustris Mill.) seeds are sensitive to damage during ccllection, processing, and storage. High-quality seeds are essential for successful production of nursery crops that meet management goals arkI perform well in the field. A series of tests was conducted to evaluate the effect of a number of presowing treatments, e.g., soaking, stratification, and coat sterilization on performance of longleaf pine seeds in the laboratory and nursery. The results of these tests that were installed to determine if presowing treatments improved seed performance are reported here.
Producing good quality seeds that perform well in the nursery continues to be challenging. High quality conifer seeds are obtained by optimizing collecting, processing, storing, and treating methodologies, and such quality is needed to consistently produce uniform nursery crops. Although new technologies are becom- ing available to evaluate seed quality, they have not been developed to the extent that they replace the more traditional methodologies developed over decades of trial and error. The most reliable approaches to predict nursery performance rely on obtaining high seed quality, applying appropriate treatments, and con- ducting germination evaluations that follow estab- lished practices.
A fertilization rate of 2 or 3 mg nitrogen (N) per week for 20 weeks yielded longleaf pine (Pinus palustris) seedlings grown inside a greenhouse that survived well and produced good root collar diameter (RCD) growth the first year after outplanting. Of a range of fertilization rates (0.5 to 4 mg N/week), the 2 mg rate yielded seedlings that did not require needle clipping during nursery production, but increased their RCD by 150% the first year after outplanting. The lower rates (3 mg N also survived well and RCD growth after one season in the field was 14% more than that of the 2 mg N rate. We are continuing to monitor seedlings to determine when they exit the grass stage.
Regenerating longleaf pine by artificial means is an essential component of restoring the ecosystem across most of its range because there are limited acres of longleaf stands remaining. Establishing longleaf pine is an early step in the ecosystem restoration process. An overview discussion of artificial regeneration techniques and related issues are presented this paper. Other papers follow in the proceedings that provide more specific information related to reestablishing longleaf pine forests.
Natural regeneration is a practical and inexpensive option for many existing southern pine forests, provided there is an adequate seed source and other stand conditions are controlled. However, seed production in natural stands of southern pines varies due to a wide range of environmental and biotic influences. It is important, then, to understand the biological processes that affect seed production in natural stands. The physiology of cone and seed production is reviewed here, and this information is applied to natural stand situations. With this knowledge, foresters will be better able to manipulate stands to improve and predict seed production and, therefore, make natural regeneration more reliable.
Longleaf pine, although widely distributed in the presettlement forests of the southern Coastal Plain, now occupies less than 10 percent of its original range. It is a highly desirable species because it resists fire, insects, and disease and produces excellent quality solid-wood products. Regeneration of the species either by natural methods or by planting of bare-root nursery stock has been difficult, and renewed interest in it has resulted in evaluation of new approaches to seedling establishment. Using container stock has greatly improved the success of longleaf pine establishment. Practical guidelines are presented that will help nursery personnel consistently produce good container stock that will survive well and initiate early height growth.
Shortleaf pine (Pinus echinata Mill.) seeds collected from six half-sib families were grown as both bareroot and container stock and outplanted on two sites in the Ouachita Mountains of Arkansas. Survival and growth were measured at years 1, 3, 5, and 10 after planting. Stock-type and family interacted to affect height at year 1 on one site. There were no other interactions through 10 years. Container stock performed consistently better than bareroot at each interval measured. There were differences among half-sib families for diameter and height on both sites for some measurement periods. Family ranks for total height early in the experiment correlated with 10 year performance on both sites.
- Dec 1969
The changing ability of seed and embryo parts of Pinus palustris Mill. and P. elliottii Engelm. to use alcohol, a product of anaerobic respiration, was studied during germination and early seedling development. From the start of germination to the 10 to 12th day, alcohol dehydrogenase (ADH) activity increased slowly in the embryos of both species. Then, as radicles emerged, activity more than doubled. Thereafter, as epicotyl emergence was completed during the next 10 days, ADH activity declined almost to zero. Highest activity was noted in the elongating portions of the radicles and epicotyls. Only after the seedlings of the two species were approaching self-sufficiency was there an indication of ADH activity in megagametophyte tissue.
- Sep 1969
Osmotic stresses greater than 8 atm markedly reduced germination of both Pinus palustris Mill. and P. elliottii Engelm, seeds. At stresses of 18 or more atm, no germination occurred. Moisture content at the onset of germination was twice as high in longleaf as in slash pine seeds.
- Nov 1968
Unstratified samples of slash pine (Pinus elliottii Engelm.) and shortleaf pine (P. echinata Mill.) germinated 82 and 50 percent after 35 years in cold, dry storage.
- Jun 1968
In Pinus taeda L. dormancy is greatest when seed is stored at 10 to 18 percent moisture. Seed is least dormant above this range but deteriorates more rapidly. Storage below 10 percent moisture is recommended to preserve viability and prevent deep dormancy.
- Sep 1965
Within limits, attenuation by wood of Pinus taeda L. by either integral or differential counting was equally satisfactory. Because the former requires simpler equipment and is more adapted to field work, it was further explored. Linear attenuation coefficients were measured for the wood (specific gravity .485 g/cm3) at various moisture contents using an integral narrow beam of gamma photons from a mock iodine-131 source. Half-thickness values and mass attenuation coefficients were also calculated for each moisture content. Results indicate that the wood has a mass attenuation coefficient very similar to that of water, greater than that of concrete or aluminum, and smaller than that of lead or tin. Half-thickness values are about twice as high for oven dry wood as for water. However, at a moisture of 50-60 percent (by volume) wood has a half-value almost identical to that of water. At this moisture content about 6 centimeters of wood between the detector and a point source will reduce the count rate by half.