Showing papers on "Bark published in 1971"
TL;DR: In this article, the southern pine beetle and allied scolytids in an outbreak area in Allen Parish, La. were associated with mites associated with the Southern pine beetle.
Abstract: Ninety-six species of mites were associated with the southern pine beetle and allied scolytids in an outbreak area in Allen Parish, La. The complex was evaluated to ascertain which species may be of value as biological control agents.
129 citations
01 Jan 1971
TL;DR: Bark formation is initiated by the cambium, which lays down xylem on the woody side and phloem, the primary bark tissue, on the bark side as mentioned in this paper.
Abstract: Bark formation is initiated by the cambium, which lays down xylem on the woody side and phloem, the primary bark tissue, on the bark side. Phloem tissue contains phloem parenchyma, bast fibers, companion cells, and the very important sieve cells or sieve tubes. These sieve elements are the main channel for the downward movement of sap and nutrients from the leaves contra to the upward rise of water from the roots in the xylem. This . layer of physiologically active tissue adjacent to the cambium is known as the inner bark and is generally relatively thin and light colored. As subsequent layers of phloem are laid down year by year, the outer layers become crushed and compressed, and the sieve elements and similar structures are collapsed. This tissue then ceases to take part in active physiological processes and is transformed into the relatively inert, dark-colored outer bark that comprises the bulk of most tree barks.
106 citations
Journal Article•
TL;DR: In this paper, a thermogravimetric analyzer was modified for the study of thermal softening of several Pacific Northwest woods and barks under constant load at a heating rate of 16 C/min.
Abstract: A thermogravimetric analyzer was modified for the study of thermal softening of several Pacific Northwest woods and barks under constant load at a heating rate of 16 C/min. Several stages of thermal softening were found in barks and wood. Regardless of species, oven-dry samples start to soften at 180 C, with termination at about 500 C. The maximum rate of softening occurred at 380 C with an additional softening at 280 C for bark and 320 C for wood of hardwood species. An increase of moisture content decreased the softening temperature. When the moisture content of either material was higher than 10%, a new maximum rate of softening appeared at 160 C, while the 280 C, 320 C and 380 C maxima were retained. The absolute softening of wood and bark at 160 C increased with increasing moisture content to a limit at about 30%. In conjunction with results from infrared spectrum, X-ray diffraction and differential thermal analysis, the heating of oven-dry wood and bark was found to exhibit neither physical nor chemical changes at less than 200 C. The softening of wood and bark in the presence of water at temperature less than 200 C must occur only in the amorphous regions, with water serving as a plasticizer. Softening of wood and bark at more than 200 C is a combined response of physical and chemical degradations. These thermal responses of wood and bark, particularly bark, are expected to be important to the strength, dimensional stability, water resistance and fire-retardant properties of composite products.
67 citations
01 Jan 1971
66 citations
TL;DR: Two dihydroisocoumarins (IIIa and IVa) have been isolated from Kigelia pinnata and their structures established as mentioned in this paper, and Stigmasterol, β-sitosterol, lapachol and 6-methoxymellein were also identified in the roots and bark.
63 citations
TL;DR: Sixteen phenolics are positively identified in oak wood; seven had not been reported in oaks before, and Lyoniside is shown to be lyoniresinol 2a- O -xyloside.
47 citations
TL;DR: Evidence is given in support of the hypothesis that the spatial arrangement of attacks by the mountain pine beetle on its host, lodgepole pine, is largely determined by the pattern of bark niches suitable for attack initiation.
Abstract: Evidence is given in support of the hypothesis that the spatial arrangement of attacks by the mountain pine beetle ( Dendroctonus ponderosae Hopk.) on its host, lodgepole pine ( Pinus contorta Dougl. var. latifolia Engelm.), is largely determined by the pattern of bark niches suitable for attack initiation. Density of attack sites and bark thickness are important in determining the attack-harbouring potential of the bark and in determining the upper limit of attacks, thus, the potential area available for attack on the bark surface of lodgepole pine trees. At fixed levels on the clear bole of naturally infested trees, attack pattern tends to be regular owing to the regular spatial pattern of suitable attack sites. The regularity of the attack pattern is disturbed by the presence of an attack-density gradient around the stem circumference. The vertical attack-density gradient over the host is well described in terms of a relation between attack density and bark thickness. This relation is asymptotic and rests on the assumption that the density of bark niches suitable for attack initiation approaches an upper limit with increasing bark thickness on lodgepole pine trees.
41 citations
34 citations
TL;DR: The hot water extractives of the fresh smooth green bark, leaves, and leaf stem twigs of a diploid Populus tremuloides tree cut in June were fractionated by ethyl acetate extraction and polyamide chromatography.
31 citations
TL;DR: Mukoeic acid, isolated from the bark of Murraya koenigii, was identified as 1-methoxy-carbazole-3-carboxylic acid (II).
TL;DR: Open-air-experiments showed, that desiccation of the root-zone, manganese deficiency and nitrogen hypertrophy decrease the inhibitory effect of the inner bark as well as its content of fungistatic substances.
Abstract: Relationships between nutrition and heart rot attack of Norway spruce (Picea abies Karst.) and the fungistatic effect of its inner bark. The fresh inner bark of Norway spruce stems and roots inhibits mycelium growth of Fomes annosus on malt agar. Nearly all fungistatic substances of the inner bark can be extracted with chloroform and acetone. The acetone-soluble fraction, which amounts to 13–27% of bark dry matter, was analysed. Up to now 12 phenolic substances have been identified, 5 of them have proved to inhibit Fomes annosus in vitro.
Open-air-experiments showed, that desiccation of the root-zone, manganese deficiency and nitrogen hypertrophy decrease the inhibitory effect of the inner bark as well as its content of fungistatic substances.
The degree of heart rot attack in older spruce stands was found to be negatively correlated with the N-, Fe- and Mn-concentrations in needles.
TL;DR: The hot water extractives of the fresh smooth green bark and the fresh leaves of a Populus deltoides Bartr. tree cut in June and processed by the Waring Blendor technique in ethanol were extracted as discussed by the authors.
Abstract: The hot water extractives of the fresh smooth green bark and the fresh leaves of a Populus deltoides Bartr. tree cut in June and processed by the Waring Blendor technique in ethanol were extracted ...
Journal Article•
TL;DR: From the bark of Aeschrion crenata Vell. as discussed by the authors, 1-carbomethoxy-β-carboline (I) and two new β-caroline bases, named crenatine (II) and Crenatidine (III), have been isolated.
TL;DR: The bark of Annona senegalensis Pers.
TL;DR: Two 19-norabietatetraenes have been isolated from jack pine and their constitution confirmed by synthesis and three 19-Norabieta-8,11,13-trien-4-ol have been detected in western white pine.
TL;DR: Anticopalic acid, a labdane diterpene not previously reported in the Gymnospermae, was found to be a major resin acid in the bark and in the wood of western white pine, Pinus monticola Dougl as discussed by the authors.
TL;DR: Several new species and new records of Indo-Malayan bark and timber beetles are reported, some of which are new to science.
Abstract: This paper deals with several new species and new records of Indo-Malayan bark and timber beetles.
TL;DR: In this paper, three alkaloids have been isolated from the root bark of Fagara viridis A. Cheval (Rutaceae) and one of them, canthin-6-one, was reported for the first time from an African species of fagara while the others are the quaternary benzophenanthridine alkaloid chelerythrine and nitidine.
TL;DR: The occurrence of the tetranortriterpenoid, angustinolide, in the seeds of Guarea trichilioides L. as well as minor amounts of β-sitosterol in the bark and wood extracts are recorded.
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01 Jan 1971
TL;DR: The Jeffrey pine beetle (Dendroctonus jeffreyi Hopk), one of the bark beetles that kill trees by mining between the bark and the wood, is the principal insect enemy of Jeffrey pine.
Abstract: The Jeffrey pine beetle (Dendroctonus jeffreyi Hopk.), one of the bark beetles that kill trees by mining between the bark and the wood, is the principal insect enemy of Jeffrey pine. The beetle is of economic importance chiefly in California, where most of the Jeffrey pine grows, and is most destructive in old-growth stands in the timber-producing areas of northeastern California. It also causes a great deal of damage to forests reserved for recreational use, such as those in the national parks.
TL;DR: Four species of Hymenoptera parasitize the miner and account for 69% of the population which survives other mortality factors and overwinters in the mine, resumes mining, and pupates in the spring in a broadened chamber at the end of the mine.
Abstract: Marmara fraxinicola Braun, a serpentine miner in the outer bark of white ash, Fraxinus americana , was investigated in central New York State. The species is univoltine. Females oviposit on smooth bark in late June and July. Immediately after 8–14 days' egg incubation, the eclosing larva penetrates the bark and feeds on the protoplast of the apparent phellogen. The larva overwinters in the mine, resumes mining, and pupates in the spring in a broadened chamber at the end of the mine. Four species of Hymenoptera parasitize the miner and account for 69% of the population which survives other mortality factors.
TL;DR: Apple trees (cv. Granny Smith) were grown in sand or water cultures supplied with a complete nutrient solution and 45Ca added to this solution c.
Abstract: Apple trees (cv. Granny Smith) were grown in sand or water cultures supplied with a complete nutrient solution. 45Ca added to this solution c. 11–14 weeks after full bloom became distributed throughout each tree. It moved preferentially into the interveinal tissues of the young rather than the old leaves of the terminal growth. The 45Ca concentration was highest in the petiole, midrib, and veins and comparable for both types of leaf in these tissues. In the tree trunk, leaders, and fruit spurs the 45Ca concentration was much higher in the bark than in the wood. Although the isotope entered the bark and leaves of the fruit spurs it was not detected in the flesh of the attached fruits. It occurred in low concentration in the pedicels of a few fruits. When supplied to trees 4–5 weeks after full bloom, 45Ca did enter the fruits, but its concentration was much less than in the bark of the fruit spurs. In such fruit the concentration of 45Ca was highest in the core towards the stem end, least in the flesh, and intermediate in the peel.