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1.
Ingela Bjurhager Lars A. Berglund Stig L. Bardage Björn Sundberg 《Journal of Wood Science》2008,54(5):349-355
Functional analysis of genes and proteins involved in wood formation and fiber properties often involves phenotyping saplings
of transgenic trees. The objective of the present study was to develop a tensile test method for small green samples from
saplings, and to compare mechanical properties of juvenile European aspen (Populus tremula) and hybrid aspen (Populus tremula × tremuloides). Small microtomed sections were manufactured and successfully tested in tension parallel to fiber orientation. Strain was
determined by digital speckle photography. Results showed significantly lower values for juvenile hybrid aspen in both Young’s
modulus and tensile strength parallel to the grain. Average Young’s moduli spanned the ranges of 5.9–6.6 and 4.8–6.0 GPa for
European aspen and hybrid aspen, respectively. Tensile strength was in the range of 45–49 MPa for European aspen and 32–45
MPa for hybrid aspen. The average density (oven-dry) was 284 kg/m3 for European aspen and 221 kg/m3 for hybrid aspen. Differences in mechanical properties correlated with differences in density.
Part of this article was presented at the 3rd International Symposium on Wood Machining, May 21–23, 2007, Lausanne, Switzerland 相似文献
2.
Current information on the root sucker ability of hybrid aspen (Populus tremula L. × P. tremuloides Michx.) is in most cases based on clone mixtures. In this study, we could separate the performance among clones by using two experimental sites with monoclonal plots of the crossing. The natural regeneration was followed for 2 years after harvest of the formerly planted stands, clear-cut at 22 and 25 years of age, respectively. We found that clonal differences were present in the number of root suckers produced per area unit and their biomass production. However, all included clones produced sufficiently many root suckers for a successful regeneration. To receive a more complete evaluation of the root sucker dynamics for future selection on the clonal level, further studies are needed where vitality, self-thinning and effects of thinning measures are coupled to the goal of the aspen forestry. 相似文献
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Reimo Lutter Arvo Tullus Arno Kanal Tea Tullus Hardi Tullus 《Scandinavian Journal of Forest Research》2017,32(8):688-699
Short-rotation forestry with hybrid aspen is a novel silvicultural system in northern Europe on former arable lands. However, knowledge about hybrid aspen growth potential in different soil types and the impact of soil physico-chemical properties on tree productivity in the long term is still scanty. We used repeated monitoring of soil properties and tree growth in young (5-year) and midterm (15-year) hybrid aspen plantations in various soil types (corresponding to four forest site types) to determine the temporal changes in tree growth–soil relationships. Growth of midterm hybrid aspen plantations exceeded same-aged native European aspen stands about two-fold. Growth had improved on Aegopodium, remained moderate on moist Dryopteris and was increasingly suppressed on dry Hepatica soils. The pHKCl, available Ca, content of clay and layer thickness of the soil A-horizon had a significant effect on tree growth in young plantations, but these effects disappeared in the midterm age. The soil water-holding capacity and available P in the A-horizon had a significant growth-controlling effect on tree growth in both ages. We concluded that former arable soils provide a sufficient supply of major nutrients in midterm hybrid aspen plantations whereas minor changes have occurred in growth–soil relationships between young and midterm age. 相似文献
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William L. Headlee Ronald S. Zalesny Jr. Richard B. Hall 《Journal of Sustainable Forestry》2019,38(1):18-30
In this study, we evaluated ‘Crandon’ coarse root biomass and architecture grown at different topographic positions and fertilizer rates. Complete excavations were conducted on a subset of trees after the first growing season and showed that root biomass was strongly related to stem biomass (R2 = 0.93), but not topographic position or fertilizer rate. After the third growing season, subsamples of roots were collected from another subset of trees and showed coarse root architecture variables to be strongly related to several metrics of the tree and root size (R2 = 0.61 to 0.82), while also differing by topographic position. Equations relating root biomass to stem biomass were derived from both methodologies (complete excavation v. subsampling for architecture measurements), and comparison of the equations indicated no difference in slopes (p = 0.59) or intercepts (p = 0.90), although the subsampling approach had a weaker model fit. Our results suggest ‘Crandon’ roots (i) adhere to strong allometric relationships with stem biomass, (ii) alter their architecture within the constraints of this allometric relationship according to site conditions, and (iii) can be subsampled to estimate root biomass from root architecture parameters with similar accuracy (but less precision) compared to complete excavations. 相似文献
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IntroductionAspen(Populus~anaDode)isapioneeringspecieswhichiswidelydistributed,welIadapted,andhasgoodqualityoftimber.ItdistributesfromXimalayaMoun-tains,toDaxing'anMountainsandXiaoxing'anMoun-tainsandfromAhaiMountainstoWusulijiangriver,coVerin23provineeso… 相似文献
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During the last 20 years a program to develop and commercialize the Pinus patula × Pinus tecunumanii hybrid, as a replacement for P. patula, has been successfully implemented. The first crosses were initiated during the early 1990s and lead to establishment of field trials across a wide variety of sites. This work gained further impetus when it became apparent that Fusarium circinatum, was causing poor post-planting survival of newly established stands of P. patula. P. tecunumanii, has been shown to be tolerant to this disease and thus a second, more comprehensive hybrid testing phase was implemented. Improvements in controlled pollination techniques and propagation methods, as well as access to genetically improved parent-stock and the use of molecular marker technology for fingerprinting was effectively utilized to greatly improve the process during this second phase. The use of artificial inoculation trials have demonstrated that the hybrid, in particular when using the low elevation (LE) provenances of P. tecunumanii, had substantially greater tolerance to F. circinatum than P. patula and survival figures from field trials support these results. Four-year volumes also indicate large growth improvements, although frost damage on certain sites presents a challenge for deployment on colder sites; and this is being tackled through breeding and accurate mapping of frost risk. Large-scale controlled pollinations and vegetative multiplication are now utilized commercially to produce the P. patula × P. tecunumanii (LE) hybrid as an alternative to P. patula. 相似文献
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Comparison of G6PDH Activity and LT50 Between P.tomentosa and P.suaveolens During Freezing Acclimation 总被引:3,自引:0,他引:3
LinShanzhi ZhangZhiyi LiuYuanzhen 《中国林学(英文版)》2003,5(1):20-24
The differences of glucose-6P dehydrogenase(G6PDH) activity and freezing resistance induced by freezing acclima-tion between cuttings of freezing-sensitive P.tomentosa and freezing-resistant P.suaveolens were compared for exploring the role of G6PDH on the enhancement of freezing resistance induced by freezing acclimation.After 5d of freezing acclimation at -3℃ ,the LT50 of P.tomentosa has deereased from -6.2℃ incontrol cuttings to -14.3℃ in freezing acclimated ones,and the increase of LT50 of P.tomentosa has decreased from -6.2℃ in control cutting to -14.3℃ in freezing acclimated ones,and the increase of G6PDH activity was observed in freezing acclimated cuttings as compared with control ones.Whereas,when P.suaveolens was freezing acclimated at -20℃ for 5d,the LT50 has decreased from -27.1℃ in control cuttings to -43.5℃ in freezing acclimated ones,and the activity of G6PDH increased considerably.In addition,the increase of LT50 and the decrease of G6PDH activity resulting from 2d of deacclimation at 25℃ were found in two kinds of freezing acclimated cuttings.It is concluded that the increase in the activity of G6PDH may associate with the inherited freezing resistance of species and the enhancemen of freezing resistance of cuttings,and may play an important role in the antifreeze process under freezing temperature,which would provide the basis for the study on the molecular mechanism of freezing resistance in P.suaveolens and the cloning of gene associated with freezing resistance. 相似文献
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Growth and nutrient responses of a P.trichocarpa × P. deltoides hybrid to phosphorus(P), copper (Cu) and zinc (Zn) were examined in a 4P× 3Cu × 3Zn factorial experiment conducted in anunheated greenhouse from 20 May until 25 August, 1997. Increase of growth medium P concentration from 37 to356 mg kg-1 resulted in a mean increase in treedry weight of 53%, and increase of P concentrationfrom 37 to 500 mg kg-1 was associated with a stemvolume increase of 47%. Increase from 0 to 0.32 µM Cu in solution applied thrice weekly wasassociated with a 61% increase in tree dry weight anda 59% increase in stem volume. There was also asmaller increase in stem volume (9.4%) resulting fromincrease in concentration of Zn from 0 to 0.31 µMin nutrient solution. Mean minimal leafconcentrations for satisfactory stem growth were foundto be 2.5 g kg-1 P, 2.4 mg kg-1 Cu and 74 mgkg-1Zn. Visual deficiency symptoms wereassociated with mean leaf P concentrations below 1.6 gkg-1, and Cu concentrations below 1.7 mgkg-1. Increase in leaf P concentration wasassociated with decreases in leaf Cu and Znconcentrations, and high leaf Zn appeared tocompensate in some degree for low leaf Cu. Totalplant dry weight was satisfactorily predicted by stemvolume (r2 = 0.85), but not by mean leaf weightor area. 相似文献
11.
Joseph Dahlen P. David Jones R. Daniel Seale Rubin Shmulsky 《Wood Science and Technology》2013,47(6):1167-1176
Visually graded Douglas-fir (DF) has wide variability within grade. Variability for 2 × 4 lumber has likely increased because harvest has shifted from federal forests to private plantation forests that contain high percentages of juvenile wood. To investigate resource variability, six No. 2, 2 × 4 DF packages were acquired from six mills. From each package, 124 samples were destructively tested in bending. Mean modulus of elasticity (MOE15) ranged from 9.8 to 13.4 GPa, and three mills did not meet the grade requirements (11.0 GPa). Bending strength (F b) ranged from 5.5 to 11.3 MPa, and three mills did not meet the grade requirements (9.3 MPa). ANOVA of MOE15 % and F b showed significant differences at the 0.05 significance level. MOE15 explained from 50 to 78 % of the variability in strength. These data suggest that variation between mills is high and destructive testing is critical for more accurate characterization of lumber properties. 相似文献
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Joseph Dahlen P. David Jones R. Daniel Seale Rubin Shmulsky 《Wood Science and Technology》2013,47(6):1153-1165
Visually graded southern pine (SP) has wide variability within grade. For 2 × 4 lumber, this variability has increased because it is harvested from both natural forests and plantation forests where trees contain high percentages of juvenile wood. To investigate resource variability, six kiln-dried No. 2 2 × 4 SP packages were acquired from six mills. From each package, 124 samples were destructively tested in bending. Mean modulus of elasticity (MOE15) ranged from 9.2 to 13.1 GPa, and three mills did not meet the design values (11.0 GPa). Bending strength (F b) ranged from 7.6 to 11.9 MPa, and four mills did not meet the design values (10.3 MPa). Analysis of variance of MOE15 and F b showed significant differences between mills. MOE15 explained from 33 to 51 % of the variability in F b. These data suggest that variation between mills is high and destructive testing is critical for more accurate characterization of lumber properties. 相似文献
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Genetic parameters for various wood density traits were estimated in 29-year-old trees of 18 full-sib families of hybrid larch
(Larix gmelinii var. japonica × Larix kaempferi) F1. Intra-ring density variation (IDV) was also evaluated using a model that expresses the pattern curve from earlywood to latewood
as a power function. A high IDV indicates an abrupt change in wood density from earlywood to latewood. The ring width and
wood density traits of individual rings were determined by X-ray densitometry. Overall wood density (RD) was shown to increase
with increasing ring number, ranging from 0.42–0.59 g/cm3, whereas IDV of individual rings decreased gradually from pith outwards. Estimates of individual tree narrow-sense heritability
of RD and IDV were 0.66 and 0.67, respectively. IDV showed negative genetic and phenotypic correlations with RD (r
g = −0.99, r
p = −0.72). The predicted genetic gains in latewood proportion and IDV were higher than that of RD. These results suggest that
the intra-ring density variation is under moderate genetic control equivalent to wood density. The trend of increasing wood
density from earlywood to latewood was associated with changes in both tracheid diameter and cell wall thickness. 相似文献
17.
V. Schefer-Immel 《Journal of pest science》1958,31(1):7-10
Zusammenfassung Im Frühjahr 1957 traten an den weiblichen Kätzchen einer bei Pappelkreuzungsversuchen als Mutterbaum benutzten Aspe in der Nähe von Hann. Münden verschiedene Schädlinge gemeinsam auf. Es handelte sich um 2 Eulen (Orthosia circellaris Hufn. undXanthia fulvago L.), einen Wickler (Epiblema nisella Cl.) und eine Fransenmotte (Batrachedra praeangusta Hw.). Die Schädlinge traten in solchem Ausmaß auf, daß an dem von mehreren Tausend Kätzchen behangenen Baum kaum eines zur Samenreifung kam.Es werden Angaben über die Biologie der Schädlinge gebracht.Ein im Gewächshaus durchgeführter Bekämpfungsversuch mit E-605 forte halte vollen Erfolg.Die Untersuchungen wurden mit Unterstützung der Landesforstverwaltungen Hessen und Niedersachsen durchgeführt. 相似文献
18.
In 1998, Mexican gray wolves (Canis lupus baileyi) were introduced into the Blue Range Wolf Recovery Area (BRWRA) that spans adjacent portions of Arizona and New Mexico. In 2009 we selected three mixed-conifer sites on the Apache National Forest, within the BRWRA of east-central Arizona, to characterize long-term age structure of aspen (Populus tremuloides) and to check for the possible occurrence of a tri-trophic cascade involving Mexican wolves, Rocky Mountain elk (Cervus elaphus nelsoni), and aspen. These mixed-conifer sites included (a) a refugium site, (b) an old-growth site, and (c) a site thinned in 1991–1992. The refugium site was inaccessible to elk and cattle whereas the old-growth and thinned sites were accessible to elk, but not cattle. Age structure results indicated that aspen recruitment (i.e., the growth of sprouts/seedlings into tall saplings, poles, and eventually trees) at the refugium site had been ongoing over a period of many decades. In contrast, aspen recruitment at the old-growth and thinned sites decreased significantly (p < 0.05) during the two most recent decades when elk populations, as indexed by annual harvest levels, were relatively “high”. From 2000 to 2008, only 2.9 Mexican wolves per 1000 elk were present on the Apache National Forest compared to 9.3 western gray wolves (Canis lupus occidentalis) per 1000 elk in Yellowstone National Park where tri-trophic cascades involving wolves, elk, and aspen have been reported. The low number of Mexican wolves relative to their primary prey (elk) suggests that an ecologically effective density of wolves has not become established in east-central Arizona. Furthermore, the lack of recent aspen recruitment in stands accessible to elk indicates an absence, to date, of a tri-trophic cascade. 相似文献
19.
M. Skrzypczyńska 《Journal of pest science》1999,72(6):164-165
Analytical studies were conducted on the species composition of galls occurring on the leaves of European aspen Populus tremula
L. in the Ojców National Park in 1997–1998. The species composition of galls was similar in two consecutive years, i.e 6 and
7 species, respectively (a total of 5492 galls). The most numerous species wasPhyllocoptes populi Nalepa in both years.
Index of occurrence frequency and Agrell’s index of species co-existence have been calculated. This index reached the highest
values in both years in case ofHarmandia cavernosa (Rübsaamen) andH. tremulae Winnertz. 相似文献