Variation In Specific Gravity Research Articles

Seed Source Variation in Specific Gravity of Loblolly Pine Grown in a Common Environment in Arkansas

Abstract Wood specific gravity in a rangewide sample of loblolly pine (Pinus taeda L.) grown in a common environment in southwest Arkansas differed from reported values of trees sampled in situ. Differences were greatest at the extremes of the species range. In the common environment trees from western and northeastern sources produced the highest specific gravities; northeastern trees produced the highest dry weight per hectare yields but they were not significantly greater than yields of trees from east coast and northwest sources. On an individual tree basis, specific gravity was significantly negatively correlated with height, diameter, and volume, although the r values were small; 0.272, 0.090, and 0.129, respectively. Provenance region correlations between specific gravity and growth and stand density parameters were generally weak to negligible. For. Sci. 36(4):1133-1145.

Juvenile wood specific gravity of loblolly pine tissue culture plantlets and seedlings

Juvenile-wood specific gravity of loblolly pine (Pinustaeda L.) tissue culture plantlets and seedlings were compared. Wood samples collected from several (6 to 13) families at three sites, each at a different age (2, 3, and 6 years), showed a significant difference between the overall plantlet and seedling mean specific gravity only in the youngest material (0.387 versus 0.356, respectively). Another collection of wood samples from three different sites at age 5 years showed that the within-site variation in specific gravity for a single clone was 29% that of the open-pollinated family from which it was derived. When tissue culture techniques become practical, operational clonal plantations of loblolly pine should offer substantial improvement in the uniformity of wood produced relative to the heterogeneous seedling-origin plantations currently being established.

Variation in biomass production, moisture content, and specific gravity in some North American willows (Salix L.)

Biomass production and quality in seedlings and coppices of Salixamygdaloides Anderss., S. eriocephala Michx., S. exigua Nutt., and S. lucida Muhl. were investigated in a full-sib family test. Between 65 and 77% of the variation in plant biomass was due to species, while less than 5% was due to families. Approximately 39% of the variation in moisture content and 37% of the variation in specific gravity was due to species differences, while only 3 and 14%, respectively, was due to families. Salixeriocephala produced the highest yields, with an average 1-year coppice production of almost 1 kg/plant (dry matter) and had the lowest moisture content and highest specific gravity of the four species. There was a strong positive correlation between seedling and coppice productivity for all species, with S. eriocephala and S. lucida producing the most vigorous regrowth from coppice.

Specific Gravity Variation in a Loblolly Pine Seed Source Study in the Western Gulf Region

Abstract Specific gravity in 28 plantings of the Western Gulf Forest Tree Improvement Program seed source study varied by provenance, family within provenance, and test location. Trees from south Arkansas had the highest specific gravity (0.424) while those from south Louisiana had the lowest (0.398). Southeast Texas and north Louisiana trees were intermediate with an average specific gravity of 0.405. Trees from a North Carolina coastal source had the lowest specific gravity in the five plantings in Arkansas and Oklahoma in which they were included. Families generally ranked the same in all tests. This implied that specific gravity was under strong genetic control and genotype by environment interaction was not operationally meaningful. However, specific gravity was environmentally sensitive as it varied significantly among locations. Environmental and genetic patterns of variation did not agree; therefore, in situ studies of regional specific gravities should not be used for making seed movement decisions. For. Sci. 34(3):798-803.

Wood factors affecting the variation in specific gravity of northern red oak ( Quercus rubra) associated with soil origin

Northern red oak ( Quercus rubra L.) specific gravity was shown to be significantly greater in wood produced on soils derived from limestone parent material than on soils derived from acid sandstone parent material. A number of wood factors were measured in order to determine the cause for the observed specific gravity differences. The factors were examined and their significance determined by both correlation and regression analyses where specific gravity was the dependent variable. The principal factors correlated with specific gravity on limestone lithologies were ring width, fiber wall thickness, and iron and magnesium in the wood ash. The major factors correlated with specific gravity on sandstone lithologies were percent vessels, percent total extractives, and magnesium in the wood ash. Significant to both lithologies, were ring width, percent total extractive content and percent vessels. It was evident that wood specific gravity is influenced by a system of complex interacting variables and variation in specific gravity associated with soil origin cannot be explained by examination of simple site factors alone.

Specific Gravity Characteristics of Recent Volcaniclastic Sediment: Implications for Sorting and Grain Size Analysis

Specific gravity of water-saturated, surface-dried individual grains and bulk, sieved samples of pumice lapilli, ash, and slightly vesiculated rock fragments produced by recent eruptions at Mount St. Helens, Washington, as well as the composition of sediment derived from this material, indicate two major departures in the character of volcaniclastics from more familiar quartzo-feldspathic sediment. These are: (1) a three-to-five-fold variation in the specific gravity of volumetrically important detrital grains, as opposed to a less than 5% variation in 99% of the volume of average quartzo-feldspathic sandstone; and (2) significant variation in specific gravity that is inversely related to grain size within clast populations of the same composition. This latter observation is attributed to the larger volume of vesicles, particularly non-interconnected vesicles, with increasing grain size. Sorting in volcaniclastic sediment, therefore, is not only a function of depositional process, environment, and post-depositional modification but also of sediment composition. Statistical analysis of sieve grain size data on weight-percent basis is inappropriate for evaluation of volcaniclastic sediments.

The role of cerebral blood volume changes in brain specific-gravity measurements

Cerebral blood volume (CBV) was calculated in gerbils from specific-gravity (SG) changes between normal and saline-perfused brains. Furthermore, changes in CBV were investigated during ischemia using carbon-14-labeled dextran (MW 70,000) as an intravascular marker. Both data were used to evaluate the possible error due to a change in CBV on the measurement of ischemic brain edema by the SG method. The methodological error found was 0.0004 for a 100% CBV change. This error is insignificant, being less than the standard deviation in the SG measured for the gerbil cortex (SG 1.0494 +/- 0.0006). Thus, CBV changes are not responsible for the SG variations observed during the first phase of ischemia. These variations are better explained as an increase of brain water content during ischemia.

Time-related changes in specific gravity and moisture content of spruce budworm killed balsam fir

The variation in specific gravity and moisture content of healthy balsam fir (Abiesbalsamea (L.) Mill.) and balsam fir killed by the spruce budworm (Choristoneurafumiferana Clem.) in northern Minnesota has been investigated. Disks were removed at 100-in. (254-cm) intervals along the merchantable boles of 31 healthy trees, 16 trees dead 6 months, 42 trees dead 12months, and 18 trees dead 22 months. Knot-free wedges were cut from the disks and separated into inner and outer sections for specific gravity and moisture content determinations. Outer and inner sections' specific gravity averages for healthy (control) balsam fir varied within tree, decreasing then increasing with height. This trend was not apparent for the outer section specific gravity averages in the dead tree categories. Average specific gravities for the four tree categories were not significantly different even 22 months after death. Tree categories' average moisture content rapidly decreased with time after death, and significant differences were detected within months of tree death. Significant outer section moisture losses occurred within 6 months after death, while significant inner section losses developed after 12 or more months.

Intra-increment variation in specific gravity of wood in blue pine

Intra-increment variation in specific gravity of wood is studied in relation to the types of annual increments in Pinus wallichiana. In the normal annual increments specific gravity increases almost linearly across the ring, displaying minimum value in the first-formed earlywood and maximum value in the last-formed latewood. The occurrence of false rings and that of compression wood in an annual ring causes a localized increase in specific gravity. The change in specific gravity at the false growth ring boundary is slight and gradual, whereas at the true annual rings boundary the change is steep and abrupt. The specific gravity in the first-formed earlywood portion gives the most consistent value as compared to whole earlywood, whole latewood and whole ring when studied around the circumference.

Root Strength in SomePopulusandSalixClones

Abstract The tensile strength of the roots of six Populus and Salix clones, and its relation to their anatomy and chemical composition, was investigated to assist selection of improved varieties for soil conservation planting. The amount of stele in the roots and its specific gravity were the most important factors determining tensile strength. Variation in specific gravity accounted for 79% of the intra-clonal variation in the tensile strength of the stele, and was also correlated with inter-clonal and seasonal variation. Fibre wall strength and specific tensile strength were correlated with S2 microfibril angle intra-clonally, cellulose content inter-clonally, and the lignin/cellulose ratio seasonally. The load required to break the roots did not increase linearly with the diameter of the roots. The results show that, in future, tensile testing is not essential in the selection of clones with the strongest roots, because these can be identified from the amount of stele in their roots and its specific gravity.

Geoclimatic Patterns in Specific Gravity and Tracheid Length in Wood of Pitch Pine

Increment cores, 12 mm diameter, were taken from pitch pine throughout its natural range and analyzed for tracheid length, unextracted specific gravity, and extracted specific gravity. Tracheid length and specific gravity increased from north to south along topoclines. However, correlations with climatic variables such as mean annual snowfall, date in the spring when mean temperature reaches 6 °C (43 °F), or daylength on that date, were more closely related to tracheid length and specific gravity than geographic location perse, indicating the existence of ecoclines. It is hypothesized that the geoclimatic patterns are the pleiotrophic result of selection for shorter. growing seasons in northern latitudes. Variance components indicated substantial variation in specific gravity among trees within stands and among areas, but not among stands in areas. For tracheid length, all three sources of variation were significant. Correlations between wood properties were low when calculated among trees within stands.

Longitudinal Variation of Specific Gravity in Stems of Black Spruce, Balsam Fir, and Lodgepole Pine

The relationship between disc specific gravity (dependent variable) and relative disc height was investigated for 50 black spruce (Piceamariana (Mill.) B.S.P.), 50 balsam fir (Abiesbalsamea (L.) Mill.), and 36 lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.). The sample trees represented various geographic areas and sizes. The simplest polynomial adequately describing the relationship was a parabola whose minimum was at mid-stem in spruce and fir and at 70% of the total height in pine. The linear term was significant only in pine and could be detected with 95% confidence if at least 14 trees were sampled. The quadratic term could be detected with 95% confidence if at least 48 spruce, or 8 fir, or 38 pine were sampled. It was concluded that the conflicting evidence in the studies concerned with the longitudinal variation of specific gravity in species of the genus Picea may be due to insufficient sample size of trees. Deviations of the sample averages from the fitted values exhibited a pattern that was similar for each species. This similarity suggested that the action of factors governing wood structure in stems of conifers depends more on the relative height in the stem than it does on species, geographic area, and absolute size.

Predicting the effect of specific gravity, moisture content, temperature and strain rate on the elastic properties of softwoods

Rational utilization of wood highes on adequate knowledge of its behavior under a wide range of conditions. Based on a literature survey, a unified system of approximate equations and correction factors is proposed. These enable one to adjust all elastic properties of wood for variations in specific gravity, moisture content, temperature and strain rate. Predicted values should be considered as useful guides to typical softwood behavior.

Variation in specific gravity of potato tubers

Specific gravity of tubers from the Irish Cobbler, Kennebec, Norgold Russet, Norland, Red Pontiac, Russet Burbank, Snowflake, and Viking varieties grown at 2 locations over 3 years were determined by the brine solution method. The usual differences in specific gravity were noted between varieties and locations. There was a narrow range in specific gravity of individual tubers within lots of Norland and Russet Burbank, and a wide range within lots of Kennebec and Snowflake, with the remaining varieties intermediate. Low variation of tubers within a variety as measured by standard deviation did not indicate low or high specific gravity. Varieties with low variation tended to remain low from one year to the next.

Transitional variation and relationships among properties within loblolly pine growth rings

Loblolly pine microtome sections 100μm thick were tested wet in tension. This thickness was approximately double the outside diameter of tracheids. Results indicate a curvilinear relationship between tensile strength and specific gravity of microspecimens combining both earlywood and latewood zones. Contrary to expectations the rate of change in slope of curve, expressed as tangent angles, decreased as specific gravity increased. Both tensile strength and stiffness values of these microspecimens are low in relation to their specific gravity. This reduction in strength and stiffness is probably related to the low ratio of microspecimen thickness to tracheid diameter, but needs further investigation. If the proper ratio between microspecimen thickness and tracheid diameter is determined, the transitional variation in tensile strength and stiffness within growth ring may be accurately established. The transitional variation in specific gravity can be successfully established from microtome sections, however the method is time consuming and not completely free of errors.

The effect of variation in specific gravity and ash content on the mechanical properties of human compact bone

The ash percentage and specific gravity were determined of samples of compact bone of the linea aspera of forty-five fresh, adult femora. Relationships were examined between these variables and the tensile strength and the modulus of elasticity of compact bone. Tensile strength was affected by variation in specific gravity of bone, but was not affected by variation within the observed range of ash percentage of the sample. The value of the modulus of elasticity was not affected by variation within the range observed of specific gravity of bone, but was affected by variation in ash percentage of the tissue.

Some studies on the shrinkage behaviour of wood

Shrinkage observed on small clear specimens in radial and tangential directions and volumetric shrinkage obtained under the evaluation of physical and mechanical properties of wood have been analysed with reference to specific gravity and fibre-saturation point (FSP). It is observed that tangential shrinkage is 1.4 to 3 times that of radial shrinkage. The difference between FSP in radial and tangential direction is not so predominant; it is possibly governed by variation in specific gravity of the wood substance. The volumetric shrinkage is noted to be approximately equal to the sum of radial and tangential shrinkages. Shrinkage is found to depend on both the specific gravity of wood and FSP. Unlike Stamm's theory, their effect is found to be additive. The effect of specific gravity is found to be more than the effect of FSP.

The estimation of carcass composition in bacon-weight pigs

Abstract The relationships between the composition and specific gravity of bacon-weight pig carcasses were investigated using carcass data from two fattening trials. In one trial bacon sides from 42 Large White pigs were fully dissected, and in the other bacon sides from 64 mainly crossbred pigs were minced and chemically analysed. The specific gravities of all six carcass joints were individually measured and correlated with their own composition and that of the whole carcass in Trial One, and with the composition of the whole carcass only in Trial Two. Specific gravity was strongly correlated with carcass composition, giving residual standard deviations between 1.47% and 1.75%. These residual standard deviations were further reduced by the inclusion of carcass measurements with specific gravity data in multiple regression equations. In both trials the correlation between whole carcass composition and specific gravity of the rib end was significantly higher than the corresponding shank end correlation. Variation in specific gravity was primarily dependent on variation in the fat content, with variation in bone content having a small effect in some joints, but not in the whole carcass. At the same specific gravity, significant differences in carcass composition were found between boar progeny groups within the Large White breed, and between litters of crossbred pigs. Sex differences had no effect on specific gravity measurements.

Variation in Specific Gravity of Cottonwood as Affected by Tree Sex and Stand Location

Variation in Specific Gravity of Cottonwood as Affected by Tree Sex and Stand Location

Inheritance of factors affecting potato chip color and their association with specific gravity

Analyses of the data from 24 progenies resulting from crossing and selfing 12 parental clones showed potato chip color to be highly heritable. Progenies with high mean chip color ratings resulted from parents with high chip color ratings. Similar results were obtained from populations of 144 or 48 individuals per progeny. Seedling varieties with high chip color ratings and those with low chip color ratings were found in all progenies. The variation of chip color appeared to be continuous. Estimates for heritability of specific gravity were lower than the heritability estimates of chip color. These estimates were substantiated by the correlation coefficients between the means of the parents and their progenies. The variation of specific gravity appeared continuous. The low correlations obtained between specific gravity and chip color rating of the parental clones indicated little relationship between the two characters. It also was apparent from the low correlations between chip color rating and specific gravity of the seedling varieties from the segregating progenies that the factors conditioning chip color and specific gravity after cold storage and reconditioning are inherited independently.