Total ring, earlywood, and latewood master chronologies were derived for six stands (three of each of the two varieties) of sand pine (Pinus clausa) spanning the geographic breadth of the species extant range in Florida, USA. Climate/growth correlations, ana- lysis of extreme growth years, and multiple regression models were developed to relate growing season (current and lagged) monthly temperature and precipitation with interannual variability in sand pine growth increments. Four research hypotheses were evaluated: (1) Sand pine growth is more sensitive to variation in precipitation than variation in temperature. (2) Sand pine growth variation is linked to El Nino-Southern Oscillation warm- vs. cold-phase events. (3) Climate/growth relations are stronger for the peninsular (Ocala; P. c. var. clausa) variety of sand pine than the panhandle (Choctawhatchee; P. c. var. immuginata) variety. (4) Climatic signals are stronger for coastal populations (vs. inland) for both varieties. Precipitation (especially in the winter/spring season of current-year growth) was more strongly linked to sand pine growth than temperature, earlywood growth was significantly greater in warm-phase El Nino-Southern Oscillation years in four of the six stands, and climate/growth relationships were stronger in coastal populations. We found no consistent inter-varietal contrasts in the strength of climatic signals, although climate/growth relationships were distinctive in the two inland pan- handle stands, where canopy/understory interactions may partially obscure expression of climatic influence. We found greater sensitivi- ty to temperature in inland panhandle stands (especially in latewood series), but consistently strong growth response to precipitation in the other four stands (especially in earlywood and total ring series). Our findings extend the evidence for ENSO influence on terrestrial biophysical phenomena in Florida. sand pine / dendroclimatology / El Nino-Southern Oscillation / Florida

The demand for southern pine fiber is increasing. However, the land resources to produce wood fiber are decreasing. The wood industry is now using intensive cultural treatments, such as competition control, fertilization, and short rotations, to increase fiber production. The impact of these intensive environmental treatments on increased growth is positive and significant, but their effects on wood properties, pulp yields, and paper properties is not well known. This pager presents research on the effect of planting density and herbaceous competition control of 14 year loblolly pine in the Piedmont and herbaceous competition control and fertilization of 17 year slash pine in the Coastal Plain on wood properties and pulp yield. Thirty-two trees of small sawlog size were harvested from each treatment and processed into lumber and residual chips using a chipping saw (CNS). Trees were also harvested from a 24 year operational loblolly plantation in the Piedmont and 24 year slash pine plantation in the Coastal Plain as controls. Specific gravity, moisture content, percent latewood, chip size and fiber length were analyzed for each treatment. The CNS chips were processed into pulp at 90 Kappa for linerboard and 60 Kappa for sack paper, and pulp yields are reported.

A computer vision-based system for lumber production planning is described. Computer axial tomography (CT or CAT) images of hardwood logs are analyzed for identification and classification of internal log defects. Individual CT image slices are analyzed for detection of 2-D defects which are correlated across CT image slices in order to establish 3-D support and identify true 3-D defects. Currently, the system is capable of 3-D reconstruction and rendering of the log and its internal defects from the individual CT image slices. It is also capable of simulation and rendering of key machining operations such as sawing and veneering on the 3-D reconstructions of the logs. From the 3-D reconstruction of the log and knowledge of its internal defects, the system can formulate sawing strategies to optimize the yield and grade of the resulting lumber. The system is intended as a decision aid for lumber production planning and an interactive training tool for novice sawyers and machinists.

By the year 2000, an estimated 50% of Georgia's pine harvest will be from managed stands (1). Because intensively managed stands are now being utilized to provide fiber from rotations as short as 12 years, wood quality issues such as density and juvenile wood are becoming increasingly important to the paper industry. Although much research has been completed in the area of tree growth and fiber quantity, wood quality parameters affecting the kraft paper industry are still relatively unknown. This presentation will review past work on the effects of plantation pine on fiber quality for paper production and discuss research into determining the impact on paper processing in the future.

Two coastal populations of Ocala sand pine (Pinus clausa (Chapm. ex Engelm.) Vasey ex Sarg. var. clausa D. B. Ward) in southeastern Florida were compared for effects of disturbances occurring at different scales on spatial dispersion and age structure. Fire has been excluded from the older population (JDO) since at least 1947; the younger population (JDY) experienced a wildfire in 1971. The two populations differed markedly in size and age structure and spatial dispersion. Density was greater and basal area was lower in JDY than in JDO. Ages in JDY were bimodally distributed, with a primary peak from 11-20 years old (delayed recruitment after the 1971 fire) and a secondary peak from 41-45 years old (earlier post-fire recruits that survived the 1971 fire). Stems in JDY were aggregated, with a positive association between seedlings and small trees. JDO had experienced more wind damage, heart rot, and mortality than JDY. Ages were unimodally distributed in JDO, with the peak from 61-70 years old; and stem distribution was random to regular. Although others have reported regeneration in canopy gaps in senescent Ocala sand pine populations in the absence of fire, JDO has shown no recruitment since 1950. With continued fire suppression and mortality of sand pine in JDO, xeric hardwoods in the understory will likely become increasingly dominant.

The paper presents a system for detection of some important internal log defects via analysis of axial CT images. Two major procedures are used. The first is the segmentation of a single computer tomography (CT) image slice which extracts defect-like regions from the image slice, the second is correlation analysis of the defect-like regions across CT image slices. The segmentation algorithm for a single CT image is basically a complex form of multiple thresholding that exploits both the prior knowledge of wood structure and gray value characteristics of the image. The defect-like region extraction algorithm first locates the pith, groups the pixels in the segmented image on the basis of their connectivity and classifies each region as either a defect-like region or a defect-free region using shape, orientation and morphological features. Each defect-like region is classified as a defect or non-defect via correlation analysis across corresponding defect-like regions in neighboring CT image slices.

Two test methods were used to assess type, location, and degree of internal stem damage to standing pine poletimber (5.0-8.9 in. diameter at breast height, DBH) caused by Hurricane Hugo. A total of sixty trees [15 from each of the four Forest Inventory Analysis (FIA) damage classes] were taken from three sites in the Francis Marion National Forest. Internal damage was expected in the form of ring shake and compression failure. Five stem sections (A through E) were taken from each tree at different heights. From each section, specimens were cut from four quadrants (Tension, Compression, Left, and Right) relative to the wind direction during the storm for toughness and tension perpendicular to the grain testing. A total of 2,147 toughness specimens were tested. A total of 273 specimens were tested in tension perpendicular to the grain. The dependent variables analyzed were toughness, tension strength, and specific gravity with FIA damage class as the whole plot factor.Although there was an increasing trend in toughness from Damage Class 1 through 4, analysis of variance showed damage class not to be a significant effect on toughness. Stem section and quadrant were found to be significant on toughness. Much of the variation in toughness due to stem section may be attributed to the effects of juvenile wood differences with tree height. Also a high occurrence of reaction wood in Quadrant C (side of the tree away from the wind) would contribute to lower toughness strength. Similarly, specific gravity (SG) values showed an overall increase from Damage Class 1 through 4. Specific gravity of Damage Class 1 and 4 was found to be significantly different. Statistical analysis showed no apparent relationship between damage class and tension strength perpendicular to the grain.The lack of evidence for internal damage is relatively unimportant compared to the evidence of change in the wood properties from the formation of reaction wood. In leaning stems (FIA Damage Classes 2, 3, 4), reaction wood should continue to form. In straight trees, reaction wood formed in the two growth seasons following the storm, but it is unclear whether it will continue to form. The results lead to the conclusion that stands with leaning stems should be harvested and replanted.

This report describes a method of testing wood specimens in tension perpendicular to the grain whereby the entire cross section of the wood may be subjected to stress. This method makes it possible to use tension perpendicular testing to detect internal tree damage such as ring separation through the entire radius of the tree. The testing procedure is performed on a solid 2- by 2-inch variable-length test specimen. Tensile stress is transferred to the test specimen through hard maple blocks that are glued to the pith and bark faces of the test specimen. The work was prompted by a study of storm-damaged trees in the Francis Marion National Forest. 1 As part of the study. sections were removed from 60 tree stems. A total of 273 specimens were tested. Tensile strength and break location were the primary variables of interest. Although the results show no conclusive evidence of internal damage. the test may be a useful alternative to the standard ASTM D 143-83 for full cross-section testing of tension perpendicular to the grain.

CSA-S347 truss plate tests were performed on three industry standard metal-plate connectors (MPCs) installed in yellow-polar and sweetgum 2 by 4's. MPCs performed well in both hardwood species. The results of this study were compared to previous results with one of the MPCs in both southern pine laminated veneer lumber and southern pine No.1 KD 2 by 4's. The wood-plate joints in sweetgum and yellow-poplar were equivalent to those in the southern pine.

Etude experimentale montrant que la distribution des classes de qualite est plus elevee pour Liriodendron tulipifera que pour Liquidambar styraciflua, et que la perte de qualite apres sechage est plus faible pour L. styraciflua. Un sechage approprie est essentiel pour reduire la degradation des bois feuillus

Opportunities exist in the hardwood lumber industry to accurately and efficiently dry hardwood lumber using computer-based process control. Systems have been commercially available for at least 10 years, yet wide spread usage of computer-based control systems has not occurred. Problems with control system accuracy, reliability, and using unconventional methods of measuring moisture content have caused the hardwood lumber industry to be cautious about adopting this new technology.

The forest resource base in the Southeast is rapidly changing. Dwindling reserves of high quality pine sawlogs will provide incentives to utilize low-density hardwoods such as yellow-poplar and sweetgum for structural lumber. Inventories of sweetgum (Liquidambar styraciflua L.) and yellow-poplar (Liriodendron tulipifera L.) are currently high and growth is exceeding removals. The mechanical properties of dimension lumber produced from sweetgum are relatively unknown. The objective of this study was to establish strength and stiffness data on sweetgum dimension lumber in bending, tension, and compression modes. The relationship between these strength modes was also investigated. Results indicate that sweetgum equals or exceeds yellow-poplar in strength and stiffness overall, and on a grade-by-grade basis. Correlations between bending, tension, and compression strength and stiffness were lower than correlations established for pine. The forest resource base in the Southeast is rapidly changing. It has been projected that plantation-grown pine, which now provides about 20 percent of the softwood resource, will provide over 50 percent of the softwood by the year 2000 (15). Plantation-grown pine has a high percentage of juvenile wood, which lowers its utility for traditional uses such as structural lumber and plywood. Projections indicate that the demand for pine timber will exceed the available supply, resulting in rising prices for pine and increased incentives for using lowdensity hardwood species such as yellow-poplar (Liriodendron tulipifera L.) and sweetgum (Liquidambar styraciflua L.) (14). Yellow-poplar structural lumber has been accepted by the American Lumber Standards Committee and the design values are published by the National Forest Products Association (9). The growth of low-density hardwood species currently exceeds the volume cut. This availability, plus the generally lower stumpage prices for mixed hardwoods (oak, poplar, sweetgum, etc.) compared to pine, has created interest in the use of hardwoods for structural framing. Grading rules for hardwood structural lumber have been proposed for several species such as aspen, alder, cottonwood, and yellow-poplar (11,12). It seems likely that on a price basis alone, suitable hardwood species will be accepted for structural applications in the near future. Over the past several years, there has been an increase in the use of machine stress rated (MSR) lumber for critical structural applications such as laminating stock, scaffold planks, and light-frame wood trusses. It seems likely that the trend toward MSR grading of lumber will also apply to hardwood structural lumber. The basis for the use of MSR lumber is the relationship of the plank bending modulus of elasticity (MOE) to the bending, compression, and tensile strength of a given structural member (adjusted for visual defects). Although the relationships between stiffness, strength, and visual defects for softwood structural lumber have been developed over the past 20 years, there has been little comparable research on these relationships for hardwoods (5-8). Because the characteristics of growth for low-density hardwoods are so different from pine with regard to the persistence of branches, size of knots, interlocked and spiral grain, etc., it is unlikely that these relationships would be the same for hardwoods. The authors are, respectively, Assistant Professor, School of Forest Resources, Univ. of Georgia, Athens, GA 30602; Forest Products Technologist and Mathematical Statistician, Southeastern Forest Expt. Sta., USDA Forest Serv., Athens, GA 30602. Gratitude is expressed to the Georgia-Pacific Corp. for donation of the lumber used in this study. This study was funded through a cooperative agreement between the USDA Forest Serv. and the Agri. Expt. Sta. at the Univ. of Georgia. This paper was received for publication in November 1989. © Forest Products Research Society 1990. Forest Prod. J. 40(10):58-64.

Damage to butt logs harvested by shear felling heads has been observed. Results show that a well-maintained shear felling head results in a 42 percent loss in tensile strength at 1.5 inches from the harvest cut. A well-maintained saw felling head showed no significant effect on tensile strength. The extent of shear damage to tensile strength is limited to within 12 inches of the harvest cut

ABSTRACT Arecent study has shown that varying glue application rates during plywood manufacturing can improve bond quality and reduce glue consumption. Current systems normally are set to control at constant application rates. The objective of this study was to test a current spray application control system for transient and frequency response characteristics to determine if variable application rate control is feasible by simply converting the software. Transient response parameters of rise time, overshoot, settling time and steady state error were measured. The system performed well below acceptable levels even with modifications made to the control valve. The modifica-tions did, however, improve system performance significantly. Frequency response tests indicated that in worst case conditions the control system could only output 38% of the control system input. Hardware changes will be necessary to improve the responsiveness of the control system to varying inputs. Steady state control of the system can be improved immediately by reducing the size of the control valve..