scholarly journals Experimental study and comparative numerical modeling of creep behavior of white oak wood with various distributions of earlywood vessel belt

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Junfeng Hou ◽  
Yingqiu Jiang ◽  
Yeqiao Yin ◽  
Weigang Zhang ◽  
Haili Chen ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Creep Behavior ◽  
Quercus Alba ◽  
White Oak ◽  
Burger Model ◽  
Oak Wood ◽  
Modeling Simulation ◽  
Instantaneous Strain ◽  
Earlywood Vessel ◽  
Cantilever Bending

AbstractMany researches have been conducted to investigate creep behavior of wood; however, the effects of structure on wood creep behavior remain unclear. Therefore, the effects of existence and distribution of earlywood vessel belt on creep behavior of white oak (Quercus alba L.) wood were investigated by dynamic thermal mechanical analyzer (DMA) with double cantilever bending in this study. Besides, a comparative numerical modeling simulation on strain curves of white oak specimens was completed using Burger and Five-parameter model. Results revealed that instantaneous strain and 45-min strain of specimens decreased with increase in the distance between earlywood vessel belt and stress acting surface obviously. Additionally, instantaneous strain and 45-min strain of specimens remarkably increased with increase in temperature from 20 to 80 °C. An obvious bending creep behavior was observed with increase in temperature from 20 to 80 °C. Both Burger and Five-parameter model can effectively simulate the creep behavior of white oak specimens with R2 values greater than 0.90. Furthermore, Five-parameter model illustrated a better fitting effect than Burger model in the final creep stage due to the introduction of a non-linear creep strain growth expression. It concluded that creep behavior of white oak wood strongly depends on the existence and distribution of earlywood vessel belt.

scholarly journals Impacts of increasing fine fuel loads on acorn germination and early growth of oak seedlings

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Rachel E. Nation ◽  
Heather D. Alexander ◽  
Geoff Denny ◽  
Jennifer K. McDaniel ◽  
Alison K. Paulson
Keyword(s):  
Prescribed Fire ◽  
Germination Rate ◽  
Growth Patterns ◽  
Leaf Number ◽  
Fuel Load ◽  
Quercus Alba ◽  
White Oak ◽  
Fuel Treatment ◽  
Basal Diameter ◽  
Fuel Loads

Abstract Background Prescribed fire is increasingly used to restore and maintain upland oak (Quercus L. spp.) ecosystems in the central and eastern US. However, little is known about how prescribed fire affects recently fallen acorns under different fine fuel loads, which can vary with stand composition and basal area, burn season, and fire frequency. We conducted plot-level (1 m2) burns in an upland oak stand in northern Mississippi, USA, during December 2018, using single (i.e., ambient), double, and triple fine fuel loads, representative of those in nearby unburned and recently fire-treated, closed-canopy stands. Pre burn, we placed 30 acorns each of white oak (Quercus alba L.) and Shumard oak (Quercus shumardii Buckley) ~1 cm below the litter surface in five plots of each fuel treatment. Immediately post burn, we planted unburned and burned acorns in a greenhouse. After ~50% of each species’ unburned acorns germinated, we measured percent germination and height, basal diameter, and leaf number of germinating seedlings weekly for 11 weeks. Then, we harvested seedlings to determine above- and belowground biomass. Results The single fuel treatment reduced acorn germination rates of both species to ~40% compared to ~88% in unburned acorns. When burned in double and triple fuel loads, acorns of both species had a <5% germination rate. There was no difference in basal diameter, leaf number, or biomass of seedlings from burned versus unburned acorns for either species. However, seedlings originating from burned acorns of both species were ~11% shorter than those from unburned acorns. Thus, both species responded similarly to fuel load treatments. Conclusions Acorns of both species exhibited greater survival with lower fine fuel loads, and consequently lower percent fuel consumption. Acorns germinating post fire generally produced seedlings with growth patterns similar to seedlings originating from unburned acorns. These findings indicate that regular, repeated prescribed fires or canopy reductions that limit fine fuel accumulation and create heterogeneous fuel beds are likely to increase acorn germination rates relative to unburned sites or those with recently introduced fire.

scholarly journals ON SOME LEAF-MINING COLEOPTERA

1872 ◽  
Vol 4 (7) ◽  
pp. 123-125
Author(s):  
V. T. Chambers
Keyword(s):  
Quercus Alba ◽  
White Oak ◽  
Leaf Mining

It is necessary for me to correct a serious error into which I have fallen.At page 165, v. 3, I have described a larva mining the upper surface of leaves of the White Oak (Quercus alba), which seemed to me to answer the requirements of Dr. Clemens' Lithocollctis tubiferella, which also mines the leaves of Quercus alba. The larva was not removed from the mine, but viewed through the integument.

scholarly journals Oak (Acorn)–Weevil Interactions across an Extensive Latitudinal Gradient in Eastern North America

Diversity ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 303
Author(s):  
Michael A. Steele ◽  
Harmony J. Dalgleish ◽  
Shealyn Marino ◽  
Andrew W. Bartlow ◽  
Rachel Curtis ◽  
...  
Keyword(s):  
Latitudinal Gradient ◽  
Quercus Rubra ◽  
Geographic Area ◽  
Eastern North America ◽  
Red Oak ◽  
Quercus Alba ◽  
White Oak ◽  
Opposite Pattern ◽  
Chemical Gradients ◽  
Latitudinal Transect

Recent studies have explored how nut weevils (Curculio and Conotrachelus spp. (Coleoptera: Curculionidae) prey on the fruits (acorns) of oak (Quercus spp.). However, few, if any, have examined these interactions over both an extensive geographic area and over several years. Here, we observed patterns of infestation in acorns of both red oak (Quercus rubra) and white oak (Quercus alba) over an eight-year period along a latitudinal transect, extending as far as 900km, across much of the shared range of these two oak species. Although weevil prevalence did not differ significantly between the two oak species, in red oak, infestation prevalence increased significantly with latitude. In contrast, an opposite pattern was evident in white oak, with the highest infestation prevalence occurring at lower latitudes. One controlled measure of cotyledon damage was significantly lower in acorns of red oak than those of white oak, which may in part be due to larger acorn size at the lower latitudes. Future investigations in this system should focus on the distribution of weevil species (with DNA barcoding) across this range and geographic variation in chemical gradients that likely determine patterns of weevil damage in individual acorns.

Nondestructive Evaluation of Red Oak and White Oak Species

2020 ◽  
Vol 70 (3) ◽  
pp. 370-377
Author(s):  
Cristian Grecca Turkot ◽  
Roy Daniel Seale ◽  
Edward D. Entsminger ◽  
Frederico José Nistal França ◽  
Rubin Shmulsky
Keyword(s):  
Modulus Of Elasticity ◽  
Longitudinal Vibration ◽  
Mechanical Tests ◽  
Modulus Of Rupture ◽  
Red Oak ◽  
Quercus Alba ◽  
White Oak ◽  
Static Modulus ◽  
Static Modulus Of Elasticity ◽  
The Relationship

Abstract The objective of this article is to evaluate the relationship between the dynamic modulus of elasticity (MOEd), which was obtained with acoustic-based nondestructive testing (NDT) methods, and static bending properties of two domestic hardwood oak species. The mechanical properties were conducted using static modulus of elasticity (MOE) and modulus of rupture (MOR) in radial and tangential directions. Mechanical tests were performed according to ASTM D143 on small clear, defect-free specimens from the two tree species: red oak (Quercus rubra) and white oak (Quercus alba). The MOEd was determined by two NDT methods and three longitudinal vibration methods based on the fast Fourier transform. The destructive strength values obtained in this study were within the expected range for these species. The MOE was best predicted by NDT methods for both species but also had a strong capability to predict MOR.

scholarly journals Phytophthora Species Detected in Two Ozark Forests with Unusual Patterns of White Oak Mortality

Plant Disease ◽  
2019 ◽  
Vol 103 (1) ◽  
pp. 102-109
Author(s):  
Sharon E. Reed ◽  
James T. English ◽  
Rose-Marie Muzika
Keyword(s):  
The United States ◽  
Phytophthora Species ◽  
Quercus Alba ◽  
White Oak ◽  
Ozark Highlands ◽  
Survey Techniques ◽  
Red Oaks ◽  
Oak Mortality ◽  
One Year ◽  
Crown Dieback

Widespread decline and mortality of white oaks (Quercus alba) occurred in Missouri Ozark forests between 2011 and 2017. Symptoms included rapid crown death with bronzing of leaves, retention of dead leaves, crown dieback and thinning, and loss of large limbs within one year of death. Decline and mortality were associated with hillside drainages and fit descriptions of European oak forests predisposed to decline by pathogenic Phytophthora species. A survey was performed at two locations in 2014 and 2015 to assess the distribution of dead and declining white oaks, and the occurrence and distribution of Phytophthora species. Multiple Phytophthora species were detected, including P. cinnamomi, P. cactorum, P. europaea, and P. pini. P. cinnamomi was the most common and widely distributed species among plots at both locations. The detection of P. cinnamomi at the base of white oaks was not associated with poor crown vigor. However, more quantitative survey techniques are necessary to clearly evaluate this relationship. P. cinnamomi kills fine roots of white and red oaks in North America and has been associated with the decline of white oaks in the United States (Ohio) and other countries. Further studies are needed to determine the importance of P. cinnamomi in oak decline within the Ozark highlands.

scholarly journals Nut Selection by Captive Blue Jays: Importance of Availability and Implications for Seed Dispersal

The Condor ◽  
2006 ◽  
Vol 108 (2) ◽  
pp. 377-388 ◽  
Author(s):  
Jeffrey E. Moore ◽  
Robert K. Swihart
Keyword(s):  
Correlation Coefficients ◽  
Discrete Choice Models ◽  
Red Oak ◽  
Quercus Alba ◽  
Northern Red Oak ◽  
White Oak ◽  
Large White ◽  
Shagbark Hickory ◽  
Black Oak ◽  
Blue Jays

Abstract We assessed dietary preference of 14 captive Blue Jays (Cyanocitta cristata) for different food types under different conditions of availability. In four separate feeding trials, we provisioned jays with the following: Trial 1, two nuts each of white oak (Quercus alba), pin oak (Q. palustris), black oak (Q. velutina), northern red oak (Q. rubra), and shagbark hickory (Carya ovata); Trial 2, two small and two large red oak acorns; Trial 3, two germinating and two nongerminating white oak acorns; and Trial 4, one large red oak acorn, one large white oak acorn, and one shagbark hickory nut. We used discrete choice models to describe selection under conditions of changing choice sets. Blue Jays displayed a clear preference for pin oak and strong avoidance of red oak acorns when alternative foods were available. White oak and black oak acorns were selected intermediately. Shagbark hickory nuts were never used. Correlation coefficients suggested that preference was inversely related to seed size and the proportion of seed consisting of hard seed coat. In the absence of alternative food items, small red oak acorns were readily taken, whereas large red oak acorns were mostly avoided but still used by some birds. These results highlight the importance of considering food availability when making conclusions about preference, and lend support to the hypothesis that Blue Jays can be important dispersers of even less-preferred oak species. We discuss the potential as well as the limitations for Blue Jays to act as seed dispersers, with respect to postglacial range expansion of fagaceous tree species, and in the context of present-day dispersal in regions where forests are highly fragmented.

Sign in / Sign up

Export Citation Format

Share Document