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.     

Retained Woody Structure in 1- to 2-Year-Old Loblolly Pine (Pinus taeda L.) Plantations in Mississippi,Louisiana, and Arkansas: Implications for Wildlife Conservation

Information regarding how site preparation techniques affect residual woody structure is lacking for the southern United States in spite of the importance of such structure for many wildlife species. Therefore, we documented retained structure in young loblolly pine (Pinus taeda L.) plantations established using four common site preparation regimes: mechanical only, chemical only, chemical + mechanical, or chemical + prescribed burning. Herbicides reduced live tree density and increased snag density relative to mechanical methods. Prescribed burning reduced density of coarse woody debris (CWD) along with density and volume of piled CWD relative to chemical and mechanical methods. Our results provide a baseline for further studies of wildlife and retained structure in southern pine forests.     

Non-destructive estimation of Pinus taeda L tracheid morphological characteristics for samples from a wide range of sites in Georgia

Tracheid coarseness, specific surface, wall thickness, perimeter, and radial and tangential diameter from 119 radial strips of Pinus taeda L. (loblolly pine) trees grown on 14 sites in three physiographic regions of Georgia (USA) were measured by SilviScan. NIR spectra were also collected in 10 mm increments from the radial longitudinal surface of each strip and split into calibration (9 sites, 729 spectra) and prediction sets (6 sites, 225 spectra). NIR spectra (untreated and mathematically treated first and second derivative and multiplicative scatter correction) were correlated with tracheid properties to develop calibrations for the estimation of these properties. Strong correlations were obtained for properties related to density, the strongest R ² being 0.80 (coarseness), 0.78 (specific surface) and 0.84 (wall thickness). When applied to the test set, good relationships were obtained for the density-related properties (R _p ² ranged from 0.68 to 0.86), but the accuracy of predictions varied depending on math treatment. The addition of a small number of cores from the prediction set (one core per new site) to the calibration set improved the accuracy of predictions and, importantly, minimized the differences obtained with the various math treatments. These results suggest that density related properties can be estimated by NIR with sufficient accuracy to be used in operational settings.     

Nondestructive estimation of wood chemical composition of sections of radial wood strips by diffuse reflectance near infrared spectroscopy

The use of calibrated near infrared (NIR) spectroscopy for predicting the chemical composition of Pinus taeda L. (loblolly pine) wood samples is investigated. Seventeen P. taeda radial strips, representing seven different sites were selected and NIR spectra were obtained from the radial longitudinal face of each strip. The spectra were obtained in 12.5 mm sections from pre-determined positions that represented juvenile wood (close to pith), transition wood (zone between juvenile and mature wood), and mature wood (close to bark). For these sections, cellulose, hemicellulose, lignin (acid soluble and insoluble), arabinan, galactan, glucan, mannan, and xylan contents were determined by standard analytical chemistry methods. Calibrations were developed for each chemical constituent using the NIR spectra, wood chemistry data and partial least squares (PLS) regression. Relationships were variable with the best results being obtained for cellulose, glucan, xylan, mannan, and lignin. Prediction errors were high and may be a consequence of the diverse origins of the samples in the test set. Further research with a larger number of samples is required to determine if prediction errors can be reduced.     

湿地松、火炬松扦插繁殖技术研究*

对影响湿地松、火炬松扦插生根的基质、生根剂及浓度、插穗状况、扦插季节、扦插方式 、扦插后管理等因子进行了研究。较佳的扦插技术组合为：用砂性土作基质，在冬季或早春采集当年生半木质化的基部萌条，湿地松用生根剂１号低浓度，火炬松用生根剂１号或２号中等浓度浸泡１５ｈ，插后保温保湿并定期喷洒营养液，生根率可达９５％以上，温室扦插苗在５月上旬以前移入大田，当年生扦插苗高达３３－４４ｃｍ，主侧根发达，可出圈造林     

Plant community responses to a gradient of site preparation intensities in pine plantations in the Coastal Plain of North Carolina

Intensively managed loblolly pine (Pinus taeda) forests are common in the southeastern United States and offer opportunities for conservation of biologic diversity. Within intensively managed landscapes, stand establishment relies on combinations of mechanical and chemical site preparation and herbaceous weed control (HWC) to manage competing vegetation and increase pine production. However, few long-term studies have described relationships between intensity of stand establishment and effects on plant communities. Therefore, we examined effects of 6 treatments that varied in intensity via combinations of mechanical (wide spacing and strip shear or narrow spacing and roller chop) and chemical (application or no application) site preparation treatments with HWC (broadcast or banded) from 1 to 8 years after site preparation on plant communities in loblolly pine plantations (n = 6) in the Coastal Plain of North Carolina, USA. All treatments resulted in abundant and diverse plant communities. Chemical site preparation had short lived (?4 year) effects on the herbaceous community but long-term effects on woody plants and pine cover. Increasing management intensity by including broadcast HWC or roller chop/narrow spacing did not additively reduce woody vegetation cover or species richness. However, broadcast HWC reduced grass, vine, and forb cover in the first year post-treatment. Average Morista community similarity values ranged from 0.69 to 0.89 among treatments and plots receiving the same chemical site preparation contained the most similar plant communities. Banded HWC can be paired with wide spacing to maximize herbaceous plant growth important for many wildlife species, particularly in the first few years after site preparation. Site preparation techniques should be tailored to local site conditions, plant communities, and management objectives.     

On an available pretreatment for the enzymatic saccharification of lignocellulosic materials

Summary In order to aim at a proved pretreatment for the enzymatic saccharification of lignocellulosic materials, the combined effect of the steam explosion treatment and the newly added alkali-hydrogen peroxide treatment was investigated. As a result, the following findings were obtained from comparison of the saccharification ratio (%) among the materials used: 1) Marked differences based on the lignocellulosic species characteristic of biological materials were observed. 2) Lignocellulosic samples such as rice straw, poplar, and maple chips gave enzymatic saccharification ratio (%) close to 100% by using the samples obtained after extraction with various solvents without alkali-hydrogen peroxide treatment. 3) Chip samples such as Japanese larch, loblolly pine, and Japanese cypress gave the very low enzymatic saccharification ratio (%) of 20–40% after the steam explosion and extraction with various solvents. 4) In comparison with enzymatic saccharification ratio (%) of original samples treated with steam explosion, alkali-hydrogen peroxide treatment resulted in greater effect based on the treatment of 2–2.5 times. 5) Alkali-hydrogen peroxide treatment afforded remarkable effects based on the treatment of the softwoods, such as Japanese larch and loblolly pine.The author is indebted to Professor Mitsuhiko Tanahashi, Faculty of Agriculture, Gifu University, for assistance on preparation of various lignocellulosic samples using a steam explosion equipment. The investigation was supported by the grant-in-aid for scientific research of the Ministry of Education in Japan     

增加林木的纤维素生产和转基因树的生长(英文)

纤维素是植物组成中的重要多聚物。纤维素也是重要的工业原料和可再生的能源物质。利用转基因技术可以降低林木中木质素含量并增加纤维素含量。木质素合成酶基因4-CL是一个重要的和木材再生有关的基因。在我们的研究中,将利用反义表达方法降低木质素含量,增加纤维素含量。研究包括:D4-CL基因的分离;转基因植物的生产;纤维素和木质素含量分析;中试。参69。     

火炬松制造中密度纤维板工艺的研究

通过对火炬松制造中纤维板制板工艺条件的研究,探索降低中密度纤维板制造过程中纤维施胶量的可能性。结果表明,火炬松制造中密度纤维板是可行的;采用８％的施胶量制板;板材的主要物理力学性能可达到美国ＭＤＦ国家标准ＡＮＳＴＡ２０８．２－１９９４和我国ＭＤＦ国家标准７０型及８０型特级品的要求。     

Aboveground biomass and nitrogen in four short-rotation woody crop species growing with different water and nutrient availabilities

We quantified the effect of water and nutrient availability on aboveground biomass and nitrogen accumulation and partitioning in four species from the southeastern United States, loblolly pine (Pinus taeda), slash pine (Pinus elliottii), sweetgum (Liquidambar styraciflua), and sycamore (Platanus occidentalis). The 6-year-old stands received five levels of resource input (control, irrigation with 3.05 cm water week⁻¹, irrigation + 57 kg N ha⁻¹ year⁻¹, irrigation + 85 kg N ha⁻¹ year⁻¹, and irrigation + 114 kg N ha⁻¹ year⁻¹). Irrigation significantly increased foliage, stem, and branch biomass for sweetgum and sycamore, culminating in 103% and 238% increases in total aboveground biomass. Fertilization significantly increased aboveground components for all species resulting in 49, 58, 281, and 132% increases in total aboveground biomass for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Standing total aboveground biomass of the fertilized treatments reached 79, 59, 48, and 54 Mg ha⁻¹ for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Fertilization increased foliar nitrogen concentration for loblolly pine, sweetgum, and sycamore foliage. Irrigation increased total stand nitrogen content by 6, 14, 93, and 161% for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Fertilization increased total nitrogen content by 62, 53, 172, and 69% with maximum nitrogen contents of 267, 212, 237, and 203 kg ha⁻¹ for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Growth efficiency (stem growth per unit of leaf biomass) and nitrogen use efficiency (stem growth per unit of foliar nitrogen content) increased for the sycamore and sweetgum, but not the loblolly or slash pine.     

The effect of weed control and fertilization on survival and growth of four pine species in the Virginia Piedmont

The growth response of loblolly pine (Pinus taeda L.), shortleaf pine (Pinus echinata Mill.), Virginia pine (Pinus virginiana Mill.), and white pine (Pinus strobus L.) to weed control and fertilization in the Piedmont of Virginia was assessed. Four different silvicultural treatments were evaluated: (1) check (no treatment); (2) weed control; (3) fertilization; (4) weed control plus fertilization. The weed control treatment included a series of herbicide and mechanical treatments to eliminate competing hardwoods. The fertilizer treatments added N, P, K, and S. Survival and growth was measured annually through age 5. There were significant differences in survival and growth among species. Survival was greatest for loblolly pine, lower in shortleaf and Virginia pine, and lowest in white pine. Fertilization without controlling the competing hardwoods decreased survival in all planted pines due to the increased hardwood competition. Loblolly pine was tallest through the 5-year period, shortleaf and Virginia pine were shorter and white pine was shortest. Silvicultural treatments had no impact on tree height but significantly affected DBH. Weed control increased DBH while fertilization did not. When applied in combination with weed control, there was no additional increase in growth of the pines due to fertilization beyond that from weed control only. Fertilization stimulated the growth of the competing hardwoods which were significantly taller in the fertilized plots.     

Restoring longleaf pine (Pinus palustris Mill.) in loblolly pine (Pinus taeda L.) stands: Effects of restoration treatments on natural loblolly pine regeneration

Historical land use and management practices in the southeastern United States have resulted in the dominance of loblolly pine (Pinus taeda L.) on many upland sites that historically were occupied by longleaf pine (Pinus palustris Mill.). There is currently much interest in restoring high quality longleaf pine habitats to such areas, but managers may also desire the retention of some existing canopy trees to meet current conservation objectives. However, fast-growing natural loblolly pine regeneration may threaten the success of artificially regenerated longleaf pine seedlings. We evaluated the establishment and growth of natural loblolly pine regeneration following different levels of timber harvest using single-tree selection (Control (uncut, residual basal area ∼16 m²/ha), MedBA (residual basal area of ∼9 m²/ha), LowBA (residual basal area of ∼6 m²/ha), and Clearcut (complete canopy removal)) and to different positions within canopy gaps (approximately 2800 m²) created by patch cutting at two ecologically distinct sites within the longleaf pine range: Fort Benning, GA in the Middle Coastal Plain and Camp Lejeune, NC in the Lower Coastal Plain. The density of loblolly pine seedlings was much higher at Camp Lejeune than at Fort Benning at the end of the first growing season after harvesting. Following two growing seasons, there were no significant effects of canopy density or gap position on the density of loblolly pine seedlings at either site, but loblolly pine seedlings were taller on treatments with greater canopy removal. Prescribed fires applied following the second growing season killed 70.6% of loblolly pine seedlings at Fort Benning and 64.3% of seedlings at Camp Lejeune. Loblolly pine seedlings were generally less than 2 m tall, and completeness of the prescribed burns appeared more important for determining seedling survival than seedling size. Silvicultural treatments that include canopy removal, such as patch cutting or clearcuts, will increase loblolly pine seedling growth and shorten the window of opportunity for control with prescribed fire. Therefore, application of prescribed fire every 2-3 years will be critical for control of loblolly pine regeneration during restoration of longleaf pine in existing loblolly pine stands.     

Growth Response of Loblolly Pine (Pinus taeda L.) 3–5 Years After Plantation Establishment Using Different Management Intensities

The upward trend of intensive management in Southern pine forests is expected to continue, both in area and intensity level. Much of the Mississippi Lower Coastal Plain (LCP) is managed intensively using some combination of mechanical site preparation, chemical site preparation, and herbaceous weed control (HWC). We studied pine growth response and competition control on loblolly pine (Pinus taeda L.) plantations 3–5 years following establishment using five combinations of chemical site preparation, mechanical site preparation, and HWC. Treatments were designated a priori as 1 (least intensive) through 5 (most intensive) largely on the basis of anticipated impact on the vegetation community. We measured pine height and diameter at breast height (dbh); woody stem density; hardwood basal area (BA); coverage of herbaceous plants, understory woody plants, and pine trees; and estimated differences in pine response using age-shift calculations at age 5. Pine height and dbh were correlated with treatment intensity; treatment 5 maintained an average advantage of 1.4-m height and 2.5-cm dbh over treatment 2, the least responsive treatment. Woody stem density varied widely and was not affected by treatment; understory woody coverage was also unaffected by treatment. Coverage of herbaceous plants was reduced in treatments receiving broadcast HWC, and in treatment 2, where slower establishment of pines may have acted as a release for competing woody plants. Age-shift gains relative to treatment 2 ranged from 0.4–1.0 years. Based on year 5 measurements of hardwood BA, it is likely that treatments 1 and 2 will fall further behind treatments 3–5 as the stands mature. Greatest control of competing vegetation and maximum growth of pines was achieved with the most intensive treatment.     

Effect of genetic sources on anatomical,morphological, and mechanical properties of 14-year-old genetically improved loblolly pine families from two sites in the southern United States

Tree improvement programs on loblolly pine (Pinus taeda) in the southeastern USA has focused primarily on improving growth, form, and disease tolerance. However, due to the recent reduction of design values for visually graded southern yellow pine lumber (including loblolly pine), attention has been drawn to the material quality of genetically improved loblolly pine. In this study, we used the time-of-flight (TOF) acoustic tool to assess the effect of genetic families on diameter, slenderness, fiber length, microfibril angle (MFA), velocity and dynamic stiffness estimated using green density (DMOE_G) and basic density (DMOE_B) of 14-year-old loblolly pine stands selected from two sites. All the 184 and 204 trees of the selected eight half-sib genetic families on sites 1 and 2 respectively were tested using TOF acoustic tool, and two 5 mm core samples taken at breast height level (1.3 m) used to for the anatomical and physical properties analysis. The results indicated a significant positive linear relationship between dynamic MOEs (DMOE_G and DMOE_B) versus tree diameter, slenderness, and fiber length while dynamic MOEs negatively but nonsignificant correlated with MFA. While there was no significant difference in DMOE_B between sites; velocity² for site 1 was significantly higher than site 2 but DMOE_G was higher for site 2 than site 1. Again, the mean DMOE_G and DMOE_B reported in the present study presents a snapshot of the expected static MOE for green and 12% moisture conditions respectively for loblolly pine. Furthermore, there were significant differences between families for most of the traits measured and this suggests that forest managers have the opportunity to select families that exhibit the desired fiber morphology for final product performance. Lastly, since the dynamic MOE based on green density (DMOE_G), basic density (DMOE_B) and velocity² present difference conclusions, practitioners of this type of acoustic technique should take care when extrapolating results across the sites.     

Effects of Acidic Precipitation and Ectomycorrhizal Inoculation on Growth,Mineral Nutrition,and Xylem Water Potential of Juvenile Loblolly Pine and White Oak

Abstract

Individual and interactive effects of simulated acidic rainfall and mycorrhizal inoculation on growth and nutrient and water relations of loblolly pine (Pinus taedaL.) and white oak (Quercus albaL.) grown in a loam soil were examined. Seedlings of each species inoculated with basidiospores of the ectomycorrhizal fungus Pisolithus tinctorius(Pers.) Coker and Couch, a known my-cobiont of both loblolly pine and white oak, and uninoculated control seedlings received two simulated rains per week of either pH 3.6, 4.2, or 4.8 for 26 weeks. Higher acidity rainfall reduced the growth but increased mycorrhizal colonization of loblolly pine, while both loblolly pine and white oak exposed to these rains exhibited greater foliar injury. Inoculation with P. tinctoriusincreased growth and reduced foliar injury of both species. Foliar concentrations of P, S, and Cu in loblolly pine and white oak, Ca in loblolly pine, and Fe and Zn in white oak decreased with increasing rain acidity while the Al concentration of both species increased. Higher rainfall acidity also reduced soil pH and Ca and Mg concentrations while increasing soil AI. Foliage of inoculated seedlings of both species had higher N and P concentrations and lower Al concentrations than control seedlings. Following the final rain applications, a drought cycle was simulated by withholding irrigation for two weeks during which seedling xylem pressure potential and soil water potential were measured. One day after cessation of irrigation, xylem pressure potential of loblolly pine that had received pH 3.6 rains was lower than that of other treatments. Thereafter, xylem pressure potential and soil water potential of the inoculated treatment decreased below those of the control treatment in both species. These results suggest that acid deposition is detrimental to juvenile loblolly pine and white oak, but the magnitude of this effect is less than the positive response to ectomycorrhizal inoculation.     

Forest herbicide influences on floristic diversity seven years after broadcast pine release treatments in central Georgia,USA

Maintenance of biodiversity is becoming a goal of forest management. This study determined effects of broadcast pine release herbicide treatments on plant species richness, diversity, and structural proportions seven years after treatment. Three study blocks were established in central Georgia. Plots 0.6–0.8 ha in size were planted to loblolly pine (Pinus taeda L.) in the Winter of 1982–83 and then treated with imazapyr (Arsenal), glyphosate (Roundup), and hexazinone (Velpar L. and Pronone 10G) in 1985. In 1992, overstory and understory (<1.5 m height) layers were examined utilizing stem and rootstock counts and basal area of overstory species and cover of understory species. ANOVA's were used to test for significance using a randomized complete block model. We found no effect of treatments on species richness. Diversity, measured separately for overstory and understory layers by Shannon-Wiener and Simpson indices, also was not influenced significantly by treatments. Arsenal significantly decreased Diospyros virginiana L. and increased Rubus argutus Link and legumes. Hexazinone treatments generally decreased Quercus nigra L., and Roundup significantly reduced Vaccinium spp. compared to the Check. We concluded that herbicide release treatments did not decrease overstory or understory plant species richness and diversity seven years post-treatment.     

Assessment of repeated application of poultry litter on phosphorus and nitrogen dynamics in loblolly pine: Implications for water quality

The Southeastern United States has a robust broiler industry that generates substantial quantities of poultry litter as waste. It has historically been applied to pastures close to poultry production facilities, but pollution of watersheds with litter-derived phosphorus and to a lesser extent nitrogen have led to voluntary and in some areas regulatory restrictions on application rates to pastures. Loblolly pine (Pinus taeda L.) forests are often located in close proximity to broiler production facilities, and these forests often benefit from improved nutrition. Accordingly, loblolly pine forests may serve as alternative land for litter application. However, information on the influence of repeated litter applications on loblolly pine forest N and P dynamics is lacking. Results from three individual ongoing studies were summarized to understand the effects of repeated litter applications, litter application rates, and land use types (loblolly pine forest and pasture) on N and P dynamics in soil and soil water. Each individual study was established at one of three locations in the Western Gulf Coastal Plain region. Annual applications of poultry litter increased soil test P accumulation of surface soils in all three studies, and the magnitude of increase was positively and linearly correlated with application rates and frequencies. In one study that was established at a site with relatively high soil test P concentrations prior to poultry litter application, five annual litter applications of 5 Mg ha⁻¹ and 20 Mg ha⁻¹ also increased soil test P accumulation in subsurface soils to a depth of up to 45 cm. Soil test P accumulations were greater in surface soils of loblolly pine stands than in pastures when both land use types received similar rates of litter application. In one study which monitored N dynamics, lower soil organic N, potential net N mineralization, potential net nitrification, and soil water N was found in loblolly pine stands than pastures after two annual litter applications. However, increases in potential net N mineralization, net nitrification, and soil water N with litter application were more pronounced in loblolly pine than in pasture soils. Loblolly pine plantations can be a viable land use alternative to pastures for poultry litter application, but litter application rate and frequency as well as differences in nutrient cycling dynamics between pine plantations and pastures are important considerations for environmentally sound nutrient management decisions.     

Chemical composition of Loblolly pine wood as related to specific gravity,growth rate,and distance from pith

Summary The alpha-cellulose, hemicellulose, holocellulose, lignin, and extractive contents of wood removed from stems of loblolly pine (Pinus taeda L.) and factorially segregated by specific gravity, rings from the pith, and growth rate were determined from sample chips. The independent relationships of each factor with chemical composition are described.

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Zusammenfassung Aus Probespänen von Loblolly pine (Pinus taeda L.) wurden die alpha-Cellulose, Hemicellulose, Holocellulose, Lignin und Extraktstoffe bestimmt und faktorenanalytisch gegen die Dichte, den Jahrringabstand vom Mark und die Wuchsgeschwindigkeit abgegrenzt. Die gereinigten Beziehungen jedes Faktors zur chemischen Zusammensetzung des Holzes werden beschrieben.In the research reported here, the chemical composition of a sample of loblolly pine wood was analyzed in relation to three readily measured gross wood characteristics: specific gravity, growth rate, and distance from the pith. As in a previous study relating fiber morphology to these three properties [McMillin, 1968], wood was removed from many stems and stratified by two densities and two growth rates at each of three radial positions in the stem. Thus, the factorial design permitted isolation of the independent relationships of each factor with various chemical components. Characterizing wood types in this way is quite distinct from studying variations in the chemical composition of stems.

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The Roy O. Martin Lumber Company, Alexandria, Louisiana, and R. A. Leask and J. Adams, Bauer Bros. Company, Springfield, Ohio, assisted in collecting and preparing the experimental material. D. Bower, Mathematical Statistician, Southern Forest Experiment Station, New Orleans, Louisiana, aided in the statistical interpretation.     

Bird community responses to a gradient of site preparation intensities in pine plantations in the Coastal Plain of North Carolina

Although intensively managed pine forests are common in the southeastern US, few studies describe how combinations of mechanical (MSP) and chemical site preparation (CSP) and herbaceous weed control (HWC) techniques affect bird communities that use early successional habitats within young pine forests. Therefore, we examined effects of six treatments of increasing management intensity via combinations of MSP (strip-shear and wide spacing or roller chop and narrow spacing) and CSP (application or no application) treatments with banded or broadcast HWC on bird communities in six loblolly pine (Pinus taeda) plantations in the Coastal Plain of North Carolina, USA, for 8 years following site preparation. Wide pine spacing and strip-shear MSP increased bird abundance and species richness over narrow spacing and chopped MSP for 6 years after planting. Chemical SP reduced bird abundance in year 2, increased bird abundance in year 6, had no effect on abundance after year 7, and did not affect species richness in any year. Total bird abundance and species richness were similar between banded and broadcast HWC. Site preparation and HWC had no effect on bird diversity and bird communities were most similar in treatments of similar intensity. Site preparation and HWC had few or no effects on birds based upon migratory status, habitat association, or conservation value. The addition of chemical site preparation or HWC had little effect on birds beyond pine spacing, and bird abundance was not proportional to management intensity. Although we observed treatment effects, all treatments provided habitat used by a variety of bird species, and pine plantations may play an increasingly important role in bird conservation as forests become fragmented and converted to other land uses and as natural processes that create early successional habitat, such as fire, are suppressed.     

Development and applications of the relative spacing model for loblolly pine plantations

The development through time of relative spacing was modeled for loblolly pine (Pinus taeda L.) plantations across the Lower Coastal Plain (LCP) and Piedmont and Upper Coastal Plain (PUCP) regions of the southern United States, using data from two culture/density studies. The lower asymptotic limit of relative spacing decreases exponentially with increasing planting density in both the LCP and PUCP regions. It is also correlated with site index in the LCP region, but not in the PUCP region. In the PUCP region, loblolly pine plantations with the intensive management regime approach a higher value of minimum relative spacing than those with the operational management regime. In the LCP region, however, for a given planting density and site index loblolly pine plantations approach the same limit of relative spacing, regardless of management regime. Site index, planting density, and management intensity also affected other model parameters. How the resulting relative spacing models are used to determine thinning schedules and indirectly derive the survival patterns over time for young loblolly pine plantations were explored and outlined.