Effect of maleic anhydride grafted styrene-ethylene-butylene-styrene （MA-SEBS） on impact fracture behavior of polypropylene / wood fiber composites

MA-SEBS as compatibilizer and impact modifier was incorporated into Polypropylene/Wood Fiber （PP/WF） to enhance interface adhesion and impact strength of the composite. The effect of MA-SEBS content on the impact fracture behavior of PP/WF composites was studied. The impact properties of composites with 8% MA-SEBS reached the maximum value. And further increasing of MA-SEBS content to 10% did not improve the fracture toughness, but improved the stiffness of composites by DMA analysis. This was attributed to the improved PP/WF adhesion. As the MA-SEBS content is more than 8%, the molecule interaction of PP and WF was expected to much stronger than lower MA-SEBS. Scanning electron microscopy （SEM） was performed to analyze the impact fracture surface and showed a stronger affinity for the wood surfaces.     

Stand biometry and leaf area distribution in an old olive grove at Andria, southern Italy

The objectives of this paper were (1) to provide general biometry data for an 80-year-old olive (Olea europea L., cv. Coratina) grove in Andria, southern Italy, and (2) to compare different methods for estimating leaf area distributions. Stand biometry was represented by a stocking density of 132 trees ha^?1, mean spacing of 8.7 m and mean social area (proportional to spacing and tree size) of about 76 m² per tree. Trunk total circumference averaged 110 cm and after subtraction of missing or dead parts of stems averaged 81 cm, projected area of crowns averaged 17.7 m² and the mean tree height was 4.9 m. Leaf distribution was evaluated using calibrated ground-based side photographs through image analysis and through using a simple canopy-layer model (considering hollow volume within tree crowns) and double-Gaussian curves. The mean leaf size was about 5 cm² (distributed in a log-normal manner over the range of 2 to 12 cm²). Considering whole tree crowns, the mean leaf density was about 2.6 m²m^?3; the maximum leaf area occurred in canopy layers between 1.5 to 3 m, tailing with a steeper slope to the crown base and a less steep slope to the tree-top. The foliated volume of olive crowns (mean 33.2 m³) contained on average 145 thousand leaves of the total area of 72.6 m². The corresponding leaf area index on the stand level (LAI _grove = 0.96), was rather low due to low stocking density. However when taking into account only the projected crown areas (and avoiding free space between trees), the mean LAI reached about 3.5 (range from 1–7). The radial pattern of leaf distribution derived from image analysis indicated peak LAI _rad values at a distance from the stem of about 60 to 70% of crown radius in trees of different size. The applicability of different approaches to the estimation of the necessary allometric parameters is discussed.     

Use and effectiveness of Washington state’s extension forest stewardship program

This paper describes the use by family forest landowners of educational programs provided by Washington State University Cooperative Extension (WSUCE), and the associated use of technical assistance programs provided by state and federal agencies and the private sector. Approximately 100,000 family forest owners controlled 19% or over 1.2 M ha of Washington’s forestland and accounted for 29% of the timber harvested in the state on a volume basis in 1998. A variety of public and private assistance and education programs are available to encourage and help family forest owners manage their forests. In 1999 a mail survey was conducted to evaluate use and effectiveness of Washington’s family forest assistance and education programs. Over half of the 872 responding family forest landowners had contact with an extension educator, program or educational material, and about three quarters of these respondents gave an overall rating of the usefulness of extension programs and materials as good or excellent. Respondents attending WSUCE forestry educational programs have larger median land ownership size, are older, have owned their forests longer, have a higher rate of absentee ownership, and are better educated than non-users. They are more likely to actively manage their forests for timber production and exhibit a clearer understanding of the multiple-use capabilities of their forests.     

Root architecture might account for contrasting establishment success of <Emphasis Type="Italic">Pseudotsuga menziesii</Emphasis> var. <Emphasis Type="Italic">menziesii</Emphasis> and <Emphasis Type="Italic">Pinus sylvestris</Emphasis> in Central Europe under dry conditions

Key message

Pinus sylvestris seedlings quickly expand their roots to deeper soil layers while Pseudotsuga menziesii concentrates its root system in the topsoil, thereby running the risk of desiccation during long dry spells, as indicated by lower survival after simulated summer drought.

Context

Pseudotsuga menziesii (Douglas-fir) is regarded as a promising species to maintain the productivity of Central European lowland forests given the projected increase of long dry spells.

Aims

Will the species be able to regenerate from seed and spread outside plantations in a drier temperate Europe?

Methods

We measured the relative growth rate, biomass allocation, root architecture, and phenotypic plasticity of Pseudotsuga menziesii seedlings sown in a common garden and grown under current precipitation and prolonged drought, respectively. The species’ competitive ability with respect to Pinus sylvestris L., the most drought-tolerant native conifer in Central Europe, was assessed during three growing seasons.

Results

Pinus sylvestris seedlings had higher relative growth rates than did Pseudotsuga menziesii seedlings, first in terms of aboveground biomass and later in terms of shoot height. This resulted in heavier and taller seedlings after three growing seasons under both moist and dry conditions. Shorter vertical roots corresponded with lower survival of Pseudotsuga menziesii seedlings under dry conditions.

Conclusion

Fast root proliferation allows Pinus sylvestris seedlings to reach deeper water pools that are less rapidly depleted during transient drought. By contrast, the shallow root system might put Pseudotsuga menziesii seedlings at the risk of desiccation during prolonged dry spells.

     

山西省蟒河自然保护区雀鹰的繁殖

1996年－1998年的3月－9月，在蟒河自然保护区对雀鹰的繁殖习性进行了观察。结果表明该鸟在本区繁殖前后的种群密度分别为0．08只/km^2和0．10只／km^2，营巢期为10d-13d，窝孵数3枚－4枚，孵卵期23d-25d，孵化率88．89％，育雏期21d-24d。其食物组成：鸟类占43．33％，鼠类占17．77％，蛙类占14．44％，昆虫占15．56％，其他占8．89％。     

What is new about new forest owners? A typology of private forest ownership in Austria

With structural changes in agriculture, new types of forest owners have become increasingly important. This article develops an empirically-based typology of forest owners in Austria. Based on a representative survey and by means of cluster analysis, seven types of forest owners are identified. These types form a sequence, ranging from forest owners with a strong agricultural background to forest owners with no agricultural background at all. The latter exhibit markedly different behaviour in various respects, e.g. in their interest in forest-related information. The increasing number of ‘new’ forest owners raises important questions for forest policy, especially how policy instruments can reach these owners and how extension services can address them.     

Stickstoffdüngungsversuche in einer Fichtenwuchsstockung (Picea abies Karst.) auf devastierter Kalkmergel-Rendzina: III. Einflüsse von Ernährungszustand und Inokulation auf die Inhaltsstoffe von Bast und Holz

Zusammenfassung In einem kombinierten Düngungs- und Infektionsversuch wurden die Beziehungen zwischen dem Ern?hrungszustand, dem Wachstum und der Rotf?uledisposition von N-Mangel-Fichten auf Kalkmergel-Rendzina geprüft. Die vorliegende Arbeit berichtet über die Wirkung der N-Düngung und künstlicher Infektionen mit Heterobasidion-Mycel auf den Gehalt an Extraktstoffen im Bast und Holz. Wurzelbast vom August (nicht aber vom April) von mehrmals gedüngten Fichten enthielt mehr Chloroform-und Ethanol/Wasser-Extrakt sowie Zucker- und Phenolkomponenten als die ungedüngten Varianten. Auch das Wurzelholz gedüngter Fichten war im August reicher an Extraktstoffen. Die N-Gaben steigerten au?erdem in beiden Geweben den Gehalt an l?slichen N-Verbindungen. Im Stamm erh?hte die Düngung die Gehalte an. Methanol-Extrakt sowie an einigen N-haltigen und phenolischen Verbindungen nur im ?u?eren Splint. Die Inokulation der St?mmchen durch Anbohren induzierte die Bildung von Reifholz und übergangszonen (zwischen Splint und verf?rbtem Reifholz), die besonders reich an Petrolether-Extrakt, Methanol-Extrakt und Lignanen waren. Diese Reaktionen der Fichten waren durch Düngung nicht beeinflu?t, da sie in inneren, vor der Düngung angelegten Stammbereichen abliefen. Die wiederholte N-Düngung führte im Wurzelbast vom April zu geringerer, in den August-Proben zu gesteigerter Hemmwirkung gegenüber Heterobasidion annosum im Biotest. Die Hemmung im August war mit dem Gehalt an phenolischen Komponenten positiv korreliert. Wurzelholz und ?u?erer Stamm-Splint von gedüngten B?umchen enthielten mehr Stickstoff und mehr Aminos?uren als die Kontrollfichten und stellten deshalb ein besonders günstiges, Substrat für den Pilz dar. Die Hemmwirkung des Reifholzes war positiv korreliert mit dem Gehalt an Methanol-Extrakt bzw. an Lignanen; ein Düngungseinflu? war nicht erkennbar. Für Stammholzfraktionen der inokulierten Fichten fand sich ein positiver Zusammenhang zwischen der Hemmwirkung und dem Gehalt an harzartigen Komponenten, die als Reaktion des Baumes auf die Verletzung vermehrt produziert wurden.

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Nitrogen fertilization experiments in a Norway spruce stand (Picea abies Karst.) of stagnant growth on devastated marly rendzina: III. Influence of fertilization and inoculation on the extractives in phloem and wood

Summary A combined fertilization and inoculation experiment was designed to study the interrelationships between nutritional status, growth, and susceptibility to heart rot of planted N-deficient Norway spruce growing on a rendzina soil (Rendoll). The present report describes the impact of N-fertilization and of inoculation withHeterobasidion annosum mycelium on the contents of extractives in the phloem and in the wood. Root phloem in August (but not in April) of spruces fertilized repeatedly contained more chloroform- and ethanol/water-soluble substances, and more sugars and phenolic compounds as compared with phloem from the controls. Root wood of fertilized trees was also richer in extractives. N-fertilization, in addition, always raised the contents of soluble N-fractions in both tissues, as well as the amount of methanol-soluble substances, N-containing compounds, and phenolics in the outer sapwood region of the stem. Inoculation of stems by introducingH.a. mycelium into auger holes induced the formation of heartwood and of transition zones (between sapwood and heartwood) which were especially rich in petrolether- and methanol-soluble substances and in lignans. These reactions were not influenced by fertilization, since they were located in the inner stem regions formed in advance of fertilization. Repeated N-application reduced the fungistatic effect onH.a. of root phloem in April but increased it in August. The inhibition in August was positively correlated with the contents of phenolic compounds. Root wood and outerstem sapwood of fertilized spruces were richer in N and amino acids than control trees and therefore offered a favorable substratum for the fungus. The inhibitory effect of heartwood was positively related to the content of methanol-soluble compounds and lignans; an effect of fertilization could not be found. For wood fractions of inoculated trees a positive interrelationship was detected between fungistatic effect and content of resin compounds, the production of which was promoted as a reaction of the tree to wounding.

     

Effects of acorn attack by curculio weevils on the germination and early growth of <Emphasis Type="Italic">Pasania edulis</Emphasis> (Makino) seedlings

We conducted field studies to evaluate the impact that curculio weevil attacks on Pasania edulis (Fagacea) acorns have on the regeneration of this tree. The germination ratio of weevil-attacked acorns was significantly lower than that of sound acorns. The number and position of the attacks on acorns affected the germination ratio. The seedlings from weevil-attacked acorns were shorter and had a smaller leaf area than those from sound acorns. The negative effects on seedling height lasted for at least three years after germination. We also studied the handling of the two types of acorns by granivorous Apodemus mice in a broad-leaved forest dominated by P. edulis. The mice picked up, transported, hoarded, and recovered sound and weevil-attacked acorns similarly. In the study site, the seedlings from weevil-attacked acorns were estimated to account for 1.5–20.4 % of the total seedlings for cohorts of mast years and 0–3.7 % for those of poor or medium acorn production. From these results, we conclude that acorns with the lower part of their cotyledons slightly damaged by weevil larvae might still be able to contribute to the regeneration of P. edulis in the field but that their contribution would be negligible or small even in mast years in this study site.     

Fine roots refilling process in an artificial gap in a Picea mongolica forest

Picea mongolica is an endemic but endangered species in China. The spruce forest is only found in sandy forest-steppe ecotones. In this study, we examined the initial response of the quantity and refilling process of fine roots in an artificial canopy gap with a diameter of 36 m in a P. mongolica forest. Under the canopy, the fine root length densities of trees, shrubs and herbs were 2,622, 864 and 3,086 m·m–2, respectively. The fine root biomass of trees, shrubs and herbs were 148, 62 and 65 g·m–2, respect...     

Bending characteristics of bamboo (<Emphasis Type="Italic">Phyllostachys pubescens</Emphasis>) with respect to its fiber–foam composite structure

The bending properties of split bamboo culm were compared with those of spruce and beech wood specimens. The bamboo allowed large flexural deformation since its outer layer retains the tensile stress while the softer inner layer undergoes large compressive deformation. The results suggested that the combination of the fiber-rich outer part and the compressible inner part was responsible for the flexural ductility of split bamboo. To clarify the compressible nature of the inner part of bamboo, the longitudinal surfaces of the bamboo and wood specimens were microscopically observed before and after a large longitudinal compression. Although the wood specimens showed serious and localized buckling, the inner part of the bamboo specimens showed no such visible buckling. In the latter case, the foam-like parenchyma cells absorbed the large compressive deformation by their microscopic buckling and simultaneously, the alignment of sclerenchyma fibers was maintained by the surrounding parenchyma matrix. The flexural elasticity of the bamboo was compared to that of the wood in respect of remaining strain during cyclic bending tests. No clear difference was recognized between their remaining strains. This fact indicated that the bamboo was not so flexible elastically, although its fiber–foam combination and intelligent fiber distribution improve flexural ductility.