Loblolly pine (Pinus taeda L.) essential oil yields affected by environmental and physiological changes

ABSTRACT

Loblolly pine (Pinus taeda L.) is one of the most abundant timber species in the United States and needles from this species contain essential oils (EOs) with antibacterial properties. Needles from trees of one loblolly pine clone were assayed for the EOs α-pinene, β-pinene, terpineol, limonene, and caryophyllene across a growing season. Results showed strong positive correlations among EOs, except for caryophyllene, with Pearson’s correlation values ranging from .66–.96. Simultaneously, physiological attributes of tree stomatal conductance, water stress, and environmental attributes including soil moisture, photosynthetic active radiation (PAR), temperature, wind speed, and relative humidity were measured. The plants modulated the EO concentrations as a function of a changing environment season. The collection month had the largest effect on EO yields and highest yields were during the beginning of the growing season. Decreases in EOs were evident as the growing season progressed and as plants exhibited greater water stress, temperatures, solar radiation, and less stomatal conductance and soil moisture. Loblolly pine’s main constituents of EOs were tightly linked and were influenced by seasonal changes (i.e., month); still, environmental/physiological attributes exhibited significant effects on α-pinene, β-pinene, and limonene concentrations. Early spring conditions with ample water were most conducive to high concentrations of EOs.     

Free proline changes in Pinus taeda L. callus in response to drought stress

The amino acid, proline (PRO), may have an important role in plant adaptation to drought stress. To study the effect of drought stress on PRO content of pine tissues, we measured free PRO by high pressure liquid chromatography in control ( -0.4 MPa) and drought-stressed ( -0.8, -1.0, -1.3, -1.6 MPa) callus tissue of Pinus taeda L. after eight weeks of growth. Drought stress was induced by adding polyethylene glycol (PEG) to the nutrient media. The relation between PRO accumulation and water potential was influenced by composition of the medium and temperature. Callus growing in media with water potentials of -0.8 MPa showed no increase in PRO compared to control callus in media at -0.4 MPa. When callus tissue was subjected to low water potentials (-1.6 MPa), endogenous PRO concentration increased 40-fold, while callus fresh weight decreased by more than 90%. When exogenous PRO was added to the nutrient media, endogenous PRO was directly proportional to the exogenous PRO concentration rather than reduction in callus growth. Thus low water potential in callus results in endogenous PRO accumulation and large reductions in callus fresh weight growth. Proline accumulation in pine cells appears to be related to mechanisms associated with tolerance to desiccation.     

Production,allocation, and stemwood growth efficiency of Pinus taeda L. stands in response to 6 years of intensive management

Loblolly pine (Pinus taeda L.) is a highly plastic species with respect to growth responses to forest management. Loblolly pine is the most planted species across the southern United States, a region with the most expansive and intensively managed forest plantations in the world. Management intensity, using tools such as site preparation and fertilization, is increasing greatly in scope over time. To better define to the productive potential of loblolly pine under intensive management, the influence of 6 years of management with weed control (W), weed control plus irrigation (WI), weed control plus irrigation and fertigation (irrigation with a fertilizer solution) (WIF), or weed control plus irrigation, fertigation, and pest control (WIFP) since plantation establishment on stand productivity in loblolly pine was examined. The site is located near Bainbridge, GA (30°48′N latitude and 84°39′W longitude) and is of medium quality (site index=18 m, base age 25). Increasing management intensity greatly accelerated stand development and biomass accumulation. At age 6 total production (above plus belowground) was nearly doubled from 50 to 93 Mg ha⁻¹ in WIFP stands compared to W stands, and standing stem biomass increased from 24 Mg ha⁻¹ in W stands to 48 Mg ha⁻¹ in response to WIFP treatment. Stem current annual increment (CAI) peaked at age 5 in the WIF and WIFP stands at 17–18 Mg ha⁻¹ per year at a basal area between 18 and 21 m² ha⁻¹. Year to year variation in CAI was better explained by previous-year leaf area index (LAI) than current-year LAI. Maximum stemwood production in loblolly pine was achieved through large increases in LAI and small decreases in allocation to woody roots (tap+coarse roots) versus woody shoots (stem+branches) associated with intensive treatments.     

Pinus taeda L. response to fertilization,herbaceous plant control,and woody plant control

On an intensively prepared site, a complete fertilizer applied at planting, and control of herbaceous and woody plants for the first 4 years, increased Pinus taeda L. volume at age 5 to 25.9 m³/ha compared to 11.8 m³/ha without the treatments. The fertilizer and competition control factors affected pine growth independently of each other, and so their effects are additive. Herbaceous plant control was the most effective treatment, increasing pine volume by 63%. Declining dry weights of herbaceous plant material indicated that pine was dominant by age 6, so more responses from herbaceous plant control are not expected. Woody plant control did not significantly increase pine volume until the fifth year because the intensive site preparation retarded the development of the woody competition. The fertilizer contained nitrogen, phosphorus, and potassium, but analysis of pine foliage indicates phosphorus was the element causing the response of pine to fertilizer. By the sixth season, the herbaceous and woody plant material contained 31% of the nitrogen and potassium applied as fertilizer. The competing material also contained 7% of the phosphorus applied in the fertilizer. This showed that competitors can be major utilizers of fertilizer applied to pines.     

Response of planted Pinus taeda L. to brush control in Northern Louisana

Eradication of brush, defined as hardwood trees, shrubs, blackberries, vines, and volunteer pines, was not necessary to maximize juvenile pine growth in northern Louisiana Pinus taeda L. plantations. Pine height and diameter gains were similar on treatments when either (1) only the above ground portion of the brush was cut yearly or (2) both the above ground stems and root systems of brush species were controlled each year. At age 10, planted pines on both treatments averaged 0.9 m taller with a 2.5 cm greater stem diameter at breast height (1.4 m) than those on untreated checks. Total outside bark volume per pine averaged 51.9 dm³ on checks vs 78.5 dm³ on treated plots.     

Intraspecific response of Pinus taeda L. to Grosmannia huntii and Leptographium terebrantis infection

We examined intraspecific and inter‐year variation in tolerance of Pinus taeda to two ophiostomatoid fungi, Leptographium terebrantis and Grosmannia huntii. Containerized seedlings of P. taeda from 27, 32, 17 and 23 different elite genetic families were artificially inoculated with L. terebrantis and G. huntii in years 2013, 2014, 2016 and 2017, respectively. Six connector families were inoculated every year. Eight weeks post‐inoculation, lesion and occlusion were measured on each seedling to determine the relative susceptibility/tolerance of families to these fungi. Pinus taeda families widely differed in these parameters suggesting intraspecific variation in the susceptibility/tolerance to the inoculated pathogens. The overall tolerance of the connector families to these fungi varied among the experimental years. These results showed that intraspecific variation to L. terebrantis and G. huntii exists among P. taeda families and it could be possible to select tolerant families to minimize the potential impact due to these fungi.     

Five-year field comparison of naturally regenerated Pinus taeda L. to genetically improved container stock,with and without release

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.     

Distribution of lignin in normal and compression wood of Pinus taeda L.

Summary The distribution of lignin in normal and compression wood of loblolly pine (Pinus taeda L.) has been studied by the technique of lignin skeletonizing. Hydrolysis of the wood carbohydrates with hydrofluoric acid left normal wood tracheids with a uniform distribution of lignin in the S1 and S2 cell wall layers. However, the S3 region of both earlywood and latewood tracheids consistently retained a dense network of unhydrolyzable material throughout, perhaps lignin.Lignin content in compression wood averaged about 7% more than in normal wood and appears to be concentrated in the outer zone of the S2 layer. The inner S2 region, despite helical checking, is also heavily lignified. The S1 layer, although thicker than normal in compression wood tracheids, contains relatively little lignin.Ray cells, at least in normal wood, appear to be lignified to the same extent, if not more so in certain cases, than the longitudinal tracheids. Other locations where lignin may be concentrated include initial pit border regions and the membranes of bordered pits.This report is a detailed excerpt from the Ph. D. dissertation of R. A. P. Financial support provided by the College of Forestry at Syracuse University and the National Defense Education Act is hereby gratefully acknowledged.     

火炬松丛生芽诱导及植株再生

采用火炬松带子叶项芽为外植体建立了组织培养再生体系。结果表明,火炬松丛生芽的形成受诱导培养基中激素浓度及外植体年龄的影响较大。适合火炬松丛生芽诱导的培养基为改良GD 6-BA 4 ms／L NAA 0．02 mg/L(诱导率86．7％),截取外植体的最佳苗龄为14-21 d。已分化的丛生芽继代培养在无6-BA但附加0．5- 1．0 g/L活性炭或0．02-0．05 mg/L NAA的培养基上伸长很快。伸长的丛生芽接种在附加0．05 ms／L NAA的1／2改良GD培养基中,1个月后有12．5％产生不定根。     

Impact of management on nutrients,carbon, and energy in aboveground biomass components of mid-rotation loblolly pine (Pinus taeda L.) plantations

Context

To sustainably manage loblolly pine plantations for bioenergy and carbon sequestration, accurate information is required on the relationships between management regimes and energy, carbon, and nutrient export.

Aims

The effects of cultural intensity and planting density were investigated with respect to energy, carbon, and essential nutrients in aboveground biomass of mid-rotation loblolly pine plantations, and the effects of harvesting scenarios on export of nutrients were tested.

Methods

Destructive biomass sampling of a 12 years-old loblolly pine culture/density experiment, and analysis of variance were used to assess the effects of cultural intensity (operational vs. intensive) and six planting densities ranging from 741 to 4,448 trees ha^?1. Two harvesting scenarios (stem-only vs. whole-tree harvesting) were assessed in terms of energy, carbon, and nutrient export.

Results

The concentrations of energy, carbon, and nutrients varied significantly among stem wood, bark, branch, and foliage components. Cultural intensity and planting density did not significantly affect these concentrations. Differences in energy, carbon and nutrient contents among treatments were mainly mediated by changes in total biomass. Nutrient contents were affected by either cultural intensity or planting density, or both. Stem-only harvesting removed 71–79 % of aboveground energy and carbon, 29–45 % of N, 28–44 % of P, 44–57 % of K, 51–65 % of Ca, and 50–61 % of Mg.

Conclusions

Stem-only harvesting would be preferred to whole-tree harvesting, from a site nutrient conservation perspective.     

Comparison of container-grown Pinus taeda L. seedlings raised outdoors and in a growth chamber in sunlight

Two annual crops of container-grown loblolly pine (Pinus taeda L.) seedlings raised outdoors differed from those grown inside a covered chamber with a clear top. After a 90-day growth period, outside-grown container seedlings had shorter heights, smaller root collar diameters, and lower root, stem, foliage, shoot, and total dry weights than chamber-grown seedlings. Fall-planted, outside-grown seedlings raised the first year had up to 10% higher field survival than those from the chamber. However, chamber-grown container seedlings that survived retained their initial height and diameter advantages following one complete growing season. Fall-planted seedlings raised the second year showed no differences due to growth treatments when favorable weather for seedling growth occurred after field-planting. Container-grown seedlings raised outdoors during the summer months are well suited for fall-outplanting.     

Fertilization of Pinus taeda L. on an acidic oxisol in southern Brazil: growth,litter accumulation,and root exploration

European Journal of Forest Research - Brazil has extensive areas planted with Pinus taeda L. primarily in southern areas with poor soil fertility and nutritional management. Identifying optimal...     

Six-year time course of light-use efficiency, carbon gain and growth of beech saplings (Fagus sylvatica) planted under a Scots pine (Pinus sylvestris) shelterwood

Two-year-old Fagus sylvatica L. saplings were planted under the cover of a Pinus sylvestris L. stand in the French Massif Central. The stand was differentially thinned to obtain a gradient of transmitted photosynthetically active radiation (PAR(t); 0-0.35). Eighteen Fagus saplings were sampled in this gradient, and their growth (basal stem diameter increment) was recorded over six years. Over the same period, morphological parameters (leaf area, number and arrangement in space) were monitored by 3D-digitization. Photosynthetic parameters were estimated with a portable gas-exchange analyzer. Photosynthesis was mainly related to light availability, whereas sapling morphology was mainly driven by sapling size. Annual stem diameter increment was related to the amount of light-intercepting foliage (silhouette to total leaf area ratio (STAR) x total sapling leaf area (LA)) and light availability above the saplings (PAR(t)). However, light-use efficiency, i.e., the slope of the relationship between STAR x LA x PAR(t) and stem diameter increment, decreased over time as a result of a relative decrease in the proportion of photosynthetic tissues to total sapling biomass.     

Vascular cambial sucrose metabolism and growth in loblolly pine (Pinus taeda L.) in relation to transplanting stress

Sucrose synthase (SS) was the dominant enzyme of sucrose metabolism in both stem and root vascular cambial zone tissues of nursery-grown loblolly pine (Pinus taeda L.) seedlings. Acid invertase (AI) and neutral invertase (NT) activities were generally less than 10% of the SS activity in both tissues. In both cambial tissues, seasonal patterns of enzyme activity were observed for SS but not for AI or NI. The seasonal patterns of SS activity in stem and root cambia paralleled the periodic growth of stems and roots. Stems had high SS activity and growth during summer and early fall. Roots had substantial SS activity and growth during summer and fall, but SS activity and growth were even higher in winter. When seedlings were transplanted, about eight months elapsed before stem and root cambia resumed rates of growth and sucrose metabolism similar to those in control nontransplanted seedlings. Two months after transplanting, root SS was at its lowest, whereas AI activity in transplants was 50% higher than in control nontransplanted seedlings. In stems, SS activity decreased in response to transplanting, whereas AI and NI activities did not change appreciably. In loblolly pine tissues, SS was specific for uridylates, whereas the nucleotide triphosphate-dependent phosphofructokinase (NTP-PFK) had similar activity with either UTP or ATP. Except in winter, the NTP-PFK was less active than the pyrophosphate-dependent phosphofructokinase (PPi-PFK) during all seasons. The PPi-dependent PFK activity in nontransplanted seedlings followed similar seasonal and spatial patterns to those of SS activity. In actively growing tissues, such as stem cambial tissues in summer and root cambial tissues in winter, the measured total PFK to SS ratio ranged between 1.5/1 and 3/1. In contrast, in less actively growing tissues or transplanted seedlings, a greater decrease occurred in SS than in PFK activity, hence the ratio rose to as high as 12/1. It was concluded that: (1) SS was the dominant enzyme for sucrose metabolism in root and stem cambial tissues of loblolly pine seedlings; (2) both SS and PPi-PFK in the cambial tissues can be used as biochemical indicators of growth sink strength in stems and roots; and (3) both enzymes can be used as indicators of seedling stress caused by events such as transplanting and winter freezing.     

Genetic effects on total phenolics, condensed tannins and non-structural carbohydrates in loblolly pine (Pinus taeda L.) needles

Carbon allocation to soluble phenolics (total phenolics, proanthocyanidins (PA)) and total non-structural carbohydrates (TNC; starch and soluble sugars) in needles of widely planted, highly productive loblolly pine (Pinus taeda L.) genotypes could impact stand resistance to herbivory, and biogeochemical cycling in the southeastern USA. However, genetic and growth-related effects on loblolly pine needle chemistry are not well characterized. Therefore, we investigated genetic and growth-related effects on foliar concentrations of total phenolics, PA and TNC in two different field studies. The first study contained nine different genotypes representing a range of genetic homogeneity, growing in a 2-year-old plantation on the coastal plain of North Carolina (NC), USA. The second study contained eight clones with different growth potentials planted in a 9-year-old clonal trial replicated at two sites (Georgia (GA) and South Carolina (SC), USA). In the first study (NC), we found no genetic effects on total phenolics, PA and TNC, and there was no relationship between genotype size and foliar biochemistry. In the second study, there were no differences in height growth between sites, but the SC site showed greater diameter (diameter at breast height (DBH)) and volume, most likely due to greater tree mortality (lower stocking) which reduced competition for resources and increased growth of remaining trees. We found a significant site?×?clone effect for total phenolics with lower productivity clones showing 27-30% higher total phenolic concentrations at the GA site where DBH and volume were lower. In contrast to the predictions of growth-defense theory, clone volume was positively associated with total phenolic concentrations at the higher volume SC site, and PA concentrations at the lower volume GA site. Overall, we found no evidence of a trade-off between genotype size and defense, and genetic potential for improved growth may include increased allocation to some secondary metabolites. These results imply that deployment of more productive loblolly pine genotypes will not reduce stand resistance to herbivory, but increased production of total phenolics and PA associated with higher genotype growth potential could reduce litter decomposition rates and therefore, nutrient availability.     

Effect of stem height,dominance class,and site quality on sapwood permeability in loblolly pine, (Pinus taeda L.)

Sapwood permeability measurements in 30-year-old green loblolly pine (Pinus taeda L.) on the Clemson Experimental Forest in the Piedmont of South Carolina, USA demonstrated that permeability is not constant and is affected by position in the bole, distance from the pith, tree dominance class, and site. Permeability increased with increasing distance from the pith and with increasing height within the tree. Sapwood area decreased with increasing height reflecting the stem taper. Sapwood area, permeability, and conductance (permeability × sapwood area) were significantly greater on stands of higher site quality. Conductance values throughout the stem were nearly equal demonstrating how permeability and sapwood area work together to affect the trees' overall transport of water from base to crown. The significant increase in permeability and conductance associated with better sites and greater dominance class may be due to more functional tracheids in the inner sapwood. Evidently, this functional tissue enhances the trees' ability to obtain adequate nutrients and water especially on good sites.     

Growth and wood density of Pinus taeda L. as affected by shelterwood harvest in a two-aged stand in Southern Brazil

Pine plantations are an important wood source in Brazil, with Pinus taeda being most frequently planted. Most pinewood is directed to the paper and pulp industry, but there is an increasing demand for wood for solid end-uses, requiring large stems from longer rotations which can be obtained using P. taeda as the canopy in two-aged stands. We evaluated radial growth and wood density at different stem heights of P. taeda in the highlands of Southern Brazil over a production period of 36 years and subjected to shelterwood harvest. Cross-sectional disks were obtained from 15 trees in different stem heights; 10 were used for growth analyses and 5 for growth and density analyses. We used disk images and X-ray techniques for growth and density analyses, respectively. Samples were analyzed for ring (width and density), earlywood, and latewood (width, density, and proportion). Ring width varied between 0.4 and 1.7 cm, with the widest rings in the first years (3–5 years.) of growth. Ring density increased with age, with higher densities on the lower stem portions. Mature wood started to be formed from the 16th ring onwards. Shelterwood harvest affected both ring width and density, but the effects on ring width lasted for at least 5 years, while the effects on wood density were short-lasting. Mature P. taeda trees increased their size after the shelterwood harvest without compromising their wood density. Longer production periods of P. taeda as retained trees in the canopy of two-aged stands provide high-quality wood for structural purposes.

     

Effects of shade on growth, biomass allocation and leaf morphology in European yew (Taxus baccata L.)

The impact of shade on the growth of European yew (Taxus baccata L.) saplings was investigated over a three-year period using artificial shading to simulate four different light regimes (3, 7, 27 and 100 % relative photosynthetic photon flux density, RPPFD). There was no mortality attributable to shading even under the 3 % RPPFD treatment. Increasing shade was positively associated with specific leaf area, leaf length, leaf width and total chlorophyll content, but negatively associated with plant height, stem diameter, total dry weight and root to leaf and shoot ratio. Discoloration of the foliage occurred in plants grown in 100 % RPPFD conditions (resulting in reduced growth rates) and those transferred to 100 % RPPFD conditions after being shade-acclimated for 2 years. Evidence suggests that T. baccata has the ability to regenerate beneath a lighter canopy but beneath denser canopies gap dynamics will play an important role in facilitating successful regeneration and this needs to be reflected in management of natural populations of this declining species.     

Diurnal changes in water conduction in loblolly pine (Pinus taeda) and Virginia pine (P. virginiana) during soil dehydration

We studied diurnal changes in water conduction during soil dehydration in 37-month-old seedlings of one Virginia pine (Pinus virginiana Mill.) and two loblolly pine (P. taeda L.) sources, one from North Carolina (NC) and the other from the "Lost Pines" areas of Texas (TX), in an environmentally controlled growth chamber. For seedlings of similar biomass, the TX source had higher values of transpiration, needle conductance, and plant hydraulic conductivity under well-watered conditions than the NC source. Under dry soil conditions, the TX source had lower values of water conduction than the NC source. The Virginia pine source responded similarly to the TX source under both well-watered and dry soil conditions. For all three pine sources, gradients between soil and needle water potentials were greatest when the seedlings were moderately stressed. The TX and Virginia pine sources had higher gradients and lower daytime needle water potentials under moderate stress conditions than the NC source. Predawn needle water potentials did not differ among the pine sources. We conclude that the TX and Virginia pine sources have decreased daytime needle water potentials and increased water potential gradients during the daytime under moderate stress conditions, but with no disruption of recovery at predawn. The greater rates of transpiration and water conduction by the TX source compared with the NC source under well-watered conditions suggest a means by which growth can be maximized prior to the onset of drought, thereby enhancing survival of loblolly pines in drought-prone environments.