Effect of stem bending on hydraulic conductivity and wood strength of loblolly pine

1994 ◽  
Vol 24 (3) ◽  
pp. 442-446 ◽  
Author(s):  
T.S. Fredericksen ◽  
R.L. Hedden ◽  
S.A. Williams
Keyword(s):  
Hydraulic Conductivity ◽  
Loblolly Pine ◽  
Modulus Of Rupture ◽  
Vertical Position ◽  
Sapwood Area ◽  
Significant Damage ◽  
Stem Bending ◽  
Average Loss ◽  
Wood Strength ◽  
Increased Susceptibility

Stems of 30-year-old loblolly pine (Pinustaeda L.) trees were bent with a winch to determine the effect of bending, which might occur from severe wind stress, on the hydraulic conductivity and wood strength of tree stems. Stems were bent to a point of imminent stem failure and then released. After release, stems leaned an average of 6.25° from their original vertical position. Measurements of sapwood permeability and viable conducting area were made on stem sections cut from bent trees and were compared with sections taken from unstressed (control) trees. Dye was used to determine the percentage of functional conducting elements. An average loss of approximately 30% in conducting sapwood area was attributed to the bending treatment. Loss of functional conducting area was greater along the axis of bending than on the lateral sides of the stem perpendicular to the direction of bending. Damage was greatest on the compression side of the stem. Despite this damage, no difference was observed in sapwood permeability due to treatment. Modulus of elasticity and modulus of rupture were reduced by 19% and 34%, respectively, on the compression side of bent stems compared with control stems. Loblolly pine appears to be capable of sustaining significant damage to its water conducting system without compromising its hydraulic conductivity. However, reduced wood strength due to bending may result in increased susceptibility to wind breakage and (or) decreased commercial value.

Assessment of the Role of Different Soil Properties on Crust Strength by Linear Regression Models

2019 ◽  
Vol 6 (04) ◽  
Author(s):  
MINAKSHI SERAWAT ◽  
V K PHOGAT ◽  
ANIL Abdul KAPOOR ◽  
VIJAY KANT SINGH ◽  
ASHA SERAWAT
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Properties ◽  
Crop Yields ◽  
Modulus Of Rupture ◽  
Silty Clay ◽  
Linear Regression Models ◽  
Wide Range ◽  
Dispersion Ratio ◽  
Crust Strength

Soil crust strength influences seedling emergence, penetration and morphology of plant roots, and, consequently, crop yields. A study was carried out to assess the role of different soil properties on crust strength atHisar, Haryana, India. The soil samples from 0-5 and 5-15 cm depths were collected from 21 locations from farmer’s fields, having a wide range of texture.Soil propertieswere evaluated in the laboratory and theirinfluence on the modulus of rupture (MOR), which is the measure of crust strength, was evaluated.The MOR of texturally different soils was significantly correlated with saturated hydraulic conductivity at both the depths. Dispersion ratio was found to decrease with an increase in fineness of the texture of soil and the lowest value was recorded in silty clay loam soil,which decreased with depth. The modulus of rupture was significantly negatively correlative with the dispersion ratio.There was no role of calcium carbonate in influencing the values of MOR of soils. Similarly,the influence of pH, EC and SAR of soil solution on MOR was non-significant.A perusal of thevalues of the correlations between MOR and different soil properties showed that the MOR of soils of Haryana are positively correlated with silt + clay (r = 0.805) followed by water-stable aggregates (r = 0.774), organic carbon (r = 0.738), silt (r = 0.711), mean weight diameter (r = 0.608) and clay (r = 0.593) while negatively correlated with dispersion ratio (r = - 0.872), sand (r = -0.801) and hydraulic conductivity (r = -0.752) of soils.

scholarly journals Influence of an Ice Storm on Aboveground Biomass of Subtropical Evergreen Broadleaf Forest in Lechang, Nanling Mountains of Southern China

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Fang Zhang ◽  
Guangyi Zhou ◽  
Motoshi Hiratsuka ◽  
Kazuo Tanaka ◽  
Yasushi Morikawa
Keyword(s):  
Aboveground Biomass ◽  
Southern China ◽  
Ice Storm ◽  
Dead Trees ◽  
Significant Damage ◽  
Short Period ◽  
Stem Bending ◽  
Biomass Loss ◽  
Extent Of Damage ◽  
Forest Rehabilitation

This study focuses on the influence of the 2008 ice storm in China and subsequent forest rehabilitation dynamics up until 2011. All seven plots studied exhibited significant damage, with the total number of damaged trees varying between 63 and 92%. In addition, most trees suffered stem bending in 2008 and the extent of damage varied with tree diameter at breast high (DBH). Relationships between loss of biomass as dead trees and stand characteristics were analyzed by multiple stepwise regression. The results showed that the decrease in biomass (Y) could be related to altitude (X1), slope (X2), and aboveground biomass (AGB) in 2008 (X5) according to the following formula:Y=−0.02456X1+0.2815X5−1.480X2+51.23. After 2 to 3 years, tree numbers had declined in all seven plots. The mean increase in AGB (4.9 t ha−1) for six of the plots was less than the biomass loss as dead trees (9.4 t ha−1) over the 3 year periods. This corresponds to a release of CO2to the atmosphere for each plot. Therefore, the forests of Lechang in the Nanling Montains have probably acted as a carbon source to the atmosphere for a short period after the 2008 ice storm.

The hydraulic architecture of Eucalyptus trees growing across a gradient of depth-to-groundwater

2015 ◽  
Vol 42 (9) ◽  
pp. 888 ◽  
Author(s):  
Sepideh Zolfaghar ◽  
Randol Villalobos-Vega ◽  
Melanie Zeppel ◽  
Derek Eamus
Keyword(s):  
Hydraulic Conductivity ◽  
Leaf Area ◽  
Water Availability ◽  
Safety Margin ◽  
Hydraulic Architecture ◽  
Sapwood Area ◽  
Huber Value ◽  
Xylem Vulnerability ◽  
Safety Margins ◽  
Hydraulic Safety

Heterogeneity in water availability acts as an important driver of variation in plant structure and function. Changes in hydraulic architecture represent a key mechanism by which adaptation to changes in water availability can be expressed in plants. The aim of this study was to investigate whether differences in depth-to-groundwater influence the hydraulic architecture of Eucalyptus trees in remnant woodlands within mesic environments. Hydraulic architecture of trees was examined in winter and summer by measuring the following traits: Huber value (HV: the ratio between sapwood area and leaf area), branch hydraulic conductivity (leaf and sapwood area specific), sapwood density, xylem vulnerability (P50 and Pe) and hydraulic safety margins across four sites where depth-to-groundwater ranged from 2.4 to 37.5 m. Huber value increased significantly as depth-to-groundwater increased. Neither sapwood density nor branch hydraulic conductivity (sapwood and leaf area specific) varied significantly across sites. Xylem vulnerability to embolism (represented by P50 and Pe) in both seasons was significantly and negatively correlated with depth-to-groundwater. Hydraulic safety margins increased with increasing depth-to-groundwater and therefore trees growing at sites with deeper water tables were less sensitive to drought induced embolism. These results showed plasticity in some, but not all, hydraulic traits (as reflected in HV, P50, Pe and hydraulic safety margin) in response to increase in depth-to-groundwater in a mesic environment.

Effect of Silvicultural Practice and Wood Type on Loblolly Pine Particleboard and Medium Density Fiberboard Properties

Holzforschung ◽  
1999 ◽  
Vol 53 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Todd F. Shupe ◽  
Chung Y. Hse ◽  
Elvin T. Choong ◽  
Leslie H. Groom
Keyword(s):  
Physical Properties ◽  
Pinus Taeda ◽  
Loblolly Pine ◽  
Medium Density Fiberboard ◽  
Thickness Swell ◽  
Modulus Of Rupture ◽  
Wood Type ◽  
Mechanical And Physical Properties ◽  
Silvicultural Practice ◽  
Strategy I

Summary The objective of this study was to determine the effect of five different silvicultural strategies and wood type on mechanical and physical properties of loblolly pine (Pinus taeda L.) particleboard and fiberboard. The furnish was prepared in an unconventional manner from innerwood and outerwood veneer for each stand. Modulus of rupture (MOR) differences between the stands were insignificant for particleboard. Some significant modulus of elastisity (MOE) differences existed between the stands for particleboard and fiberboard. Differences between the wood types were minimal for each stand. Innerwood yielded higher mean MOR, MOE, and internal bond (IB) values than outerwood for most of the stands. The differences between the stand and wood types for 2 and 24 h thickness swell and 2 and 24h water adsorption were very minimal. This research has shown that innerwood can produce particleboard and fiberboard panels with very comparable mechanical and physical properties to outerwood. The effect of the silvicultural strategy (i. e., stand) was minimal for most properties.

Effect of Mid-Rotation Fertilization on Stiffness and Strength of Loblolly Pine Wood

IAWA Journal ◽  
2013 ◽  
Vol 34 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Finto Antony ◽  
Laurence R. Schimleck ◽  
Richard F. Daniels ◽  
Alexander Clark
Keyword(s):  
Loblolly Pine ◽  
Treatment Effect ◽  
Nitrogen Fertilizer ◽  
Modulus Of Elasticity ◽  
Block Design ◽  
Modulus Of Rupture ◽  
Significant Treatment Effect ◽  
Significant Treatment ◽  
Randomized Complete Block Design ◽  
Four Levels

Trees sampled from a loblolly pine mid-rotation fertilization trial were used in this study. The study was laid out in a randomized complete block design with four levels of nitrogen fertilizer as treatments: control (000N), 112 (112N), 224 (224N), and 336 (336N) kg/ha of nitrogen, with each treatment replicated in 4 blocks. Two trees were destructively sampled from each plot giving a total of 32 trees. Bolts 0.6 m in length were collected from each tree (3 bolts per tree); with the midpoint of each bolt at heights of 2.4, 7.3 and 12.2 m from the base of the tree (each bolt represented the midpoint of standard 4.9 m saw logs). Static bending samples with dimensions 25 by 25 by 406 mm (radial, tangential and longitudinal dimensions respectively) were cut from the bolts that included the 25 mm of wood produced immediately following fertilization. Data on modulus of elasticity (MOE, stiffness) and modulus of rupture (MOR, strength) were collected from clear static bending samples. Based on the analysis of variance, no significant treatment effect was observed on MOE and MOR. However, MOE and MOR decreased in wood produced immediately after fertilization for trees which received the highest level of fertilization (336N). A decreasing trend in MOE and MOR with height was also present.

Reduction in branch sapwood hydraulic permeability as a factor limiting survival of lower branches of lodgepole pine

2000 ◽  
Vol 30 (7) ◽  
pp. 1088-1095 ◽  
Author(s):  
Clark G Protz ◽  
Uldis Silins ◽  
Victor J Lieffers
Keyword(s):  
Hydraulic Conductivity ◽  
Stomatal Conductance ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Hydraulic Permeability ◽  
Low Light ◽  
Sapwood Area ◽  
Canopy Trees ◽  
Closed Canopy ◽  
Eventual Death

Branch sapwood hydraulic permeability, tracheid size, and earlywood to latewood ratio of annual rings were examined in lower and upper branches of closed-canopy and open-grown lodgepole pine (Pinus contorta Dougl. ex Loud.) trees. Hydraulic permeability, expressed on either a leaf area or sapwood area basis, was lower in lower branches (0.16 × 10-5 and 5.82 × 10-5 m2, respectively) than upper branches (0.26 × 10-5 and 10.47 × 10-5 m2, respectively) and was related to narrower tracheids in the sapwood of lower branches. Earlywood/latewood ratio declined in the lower branches of shaded trees. The hydraulic conductivity of upper and lower branches in closed canopy trees was reduced by drilling small holes radially through the stem. Stomatal conductance was lower, and after a growing season there was greater foliage mortality in drilled lower crown branches than in similarly treated upper branches, suggesting that the hydraulic conductivity of lower branches was closer to the lower limit required to maintain foliage than in upper branches. These data suggest that high foliage mortality and eventual death of lower branches does not occur solely because of low light but also from reduced stomatal conductance and photosynthesis resulting from shade-initiated reductions in earlywood, tracheid diameter, and branch hydraulic conductivity.

scholarly journals Impact of Heavy Glaze in a Loblolly Pine Spacing Trial

1996 ◽  
Vol 20 (3) ◽  
pp. 151-155 ◽  
Author(s):  
Ralph L. Amateis ◽  
Harold E. Burkhart
Keyword(s):  
Analysis Of Variance ◽  
Loblolly Pine ◽  
Significant Relationship ◽  
Proportional Odds Model ◽  
Tree Level ◽  
Ice Storm ◽  
Strong Correlations ◽  
Individual Tree ◽  
Damage Prediction ◽  
Stem Bending

Abstract In March 1994, a severe ice storm badly damaged an 11-yr-old loblolly pine spacing study in central Virginia. After the storm, trees in the spacing trials were categorized into one of five stem and top damage classes. Analysis of variance procedures indicated no significant relationship between stem and top damage and spacing or density. Forked trees were found to be more susceptible to ice damage than single-stemmed trees. At an individual tree level, strong correlations were found between diameter and height and the type (stem bending or top breakage) and severity of damage. Prediction equations were developed for estimating the probability of five levels of stem bending and top breakage based on a proportional odds model. South. J. Appl. For. 20(3):151-155.

scholarly journals Relative resistance to breaking of Pinus taeda and Pinus palustris

2018 ◽  
Vol 92 (4) ◽  
pp. 417-424 ◽  
Author(s):  
Cory Garms ◽  
Thomas J Dean
Keyword(s):  
Loblolly Pine ◽  
Modulus Of Elasticity ◽  
Longleaf Pine ◽  
Basal Area ◽  
Bending Moment ◽  
Pinus Palustris ◽  
Modulus Of Rupture ◽  
Pine Wood ◽  
Pine Tree ◽  
Crown Length

Abstract Patterns from hurricane damage indicate that longleaf pine is more windfirm than loblolly pine. Tree windfirmess has been attributed to many factors including species and material properties like wood strength and stiffness. Because longleaf pine wood is stronger and stiffer than loblolly pine wood, this study used static winching methodology to see if these properties account for differences in wind firmness by measuring bending force required to break stems (MMAX). Stress–strain diagrams were constructed for pulled trees to explore how they behave under increasing loads. Based on these diagrams, living trees appear to act as linear elastic materials as they experience increasing static lateral stress. As expected, longleaf pine stems were stiffer than loblolly pine wood in situ based on Young’s modulus of elasticity. Tree basal area was the best predictor of MMAX for both species, however, species had no significant effect on the maximum bending moment required to break tree stems of a given basal area for these trees under these conditions. The stiffness of the stems was higher for longleaf than loblolly as indicated by the modulus of elasticity, but the strength of the stems as indicated by the modulus of rupture was not significantly different between the species. Differences in the volumetric density of foliage, however, were consistent with the observed differences in stem failure between the species. For trees with the same diameter, loblolly pine had higher values of leaf area per unit crown length than longleaf pine.

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