oalib

OALib Journal期刊

ISSN: 2333-9721

费用:99美元

投稿

匹配条件: “birch” ,找到相关结果约65条。
列表显示的所有文章,均可免费获取
第1页/共65条
每页显示
Assessing Biomass Expansion Factor of Birch Tree Betula utilis D. DON  [PDF]
Khurshid Alam, Syed Moazzam Nizami
Open Journal of Forestry (OJF) , 2014, DOI: 10.4236/ojf.2014.43024
Abstract:

Biomass is the component of living organism and mostly obtained from plants, animals, insects and the residue of all the mentioned organisms. Biomass is the key source of energy present in the form of organic matter. The study aimed to find out biomass and its variation in each component of Betula utilis D. Don (Birch Tree) with varying diameter at Kalam forest division Swat, Khyber Pakhtunkhwa (KPK) province, Pakistan. The biomass of different components was determined by non-destructive methods. Overall, 30 trees were selected from different diameter classes viz a viz up to 10, 11 - 20 and greater than 20 cm. Ten trees were selected from each class. The diameter of stem and large branches and their length were measured in the field. Later, the volumes of stem and branches were calculated and converted into biomass. The study revealed that stem contributes 42.65% biomass followed by large and sub branches as 39.22% and 13.54% respectively. Leaves contribute 4.59% only. The above tree biomass contribution by different components was arranged as stem was greater than large branches; these were greater than sub branches and the lowest was in leaves. The total above ground biomass of single tree was 20.59, 58.041 and 197.214 kg·tree-1 respectively for diameter up to 10, 11 - 20 and greater than 20 cm. The averaged biomass in all diameter classes was 91.95 ± 93.064 kg·tree-1. The total biomass of single tree of diameter class up to 10, 11 - 20 and greater than 20 cm was 24.71, 69.649 and 236 kg respectively. The below ground biomass of single tree of diameter class

Wybrane wska niki jako ci technicznej drewna brzozy brodawkowatej (Betula pendula Roth.) w pó nocno-wschodniej Polsce
Hubert Lachowicz
Forest Research Papers , 2010, DOI: 10.2478/v10111-010-0010-5
Abstract: Wood resistance and structural parameters with the consideration of the geographical location and tree age were selected for the study of the variability in technical quality of silver birch wood. The study area covered the northeastern part of the birch timber resource basis in Poland. Trees were sampled at aged 45 and 70 years, in the sites located in the fresh broadleaved forest. The most important result of the paper is the confirmed significance of both geographical location and tree age for the mean width of annual wood rings. Another finding is the statistically significant effect of geographical location on birch wood density and its mechanical properties. No significant effect of tree age on wood density and mechanical properties of birch wood has been found. The highest values of resistance to static bending as well as the elasticity coefficient obtained during static bending have been stated for the Soko ów Podlaski Forest District: 131.4 MPa and 14741 MPa, respectively; while the lowest values obtained for the P ońsk Forest District were 121.5 MPa and 13447 MPa, respectively (the differences reaching 8.1% and 9.6%). In the Forest Districts Soko ów Podlaski and Bia a Podlaska, the following birch wood parameters had their maximum values: wood density, compression resistance along fibers, static bending and coefficient of elasticity during static bending.
Genotoxicity Assessment of Birch-Bark Tar—A Most Versatile Prehistoric Adhesive  [PDF]
A. Baumgartner, M. Sampol-Lopez, E. Cemeli, T. E. Schmid, A. A. Evans, R. E. Donahue, D. Anderson
Advances in Anthropology (AA) , 2012, DOI: 10.4236/aa.2012.22006
Abstract: In the Mesolithic, birch-bark tar was commonly utilized across Europe and much of Asia as an adhesive to bind, seal and coat surfaces, but also quite frequently it was found to be chewed. The tar is known to contain biomarker triterpenoid compounds like betulin, crucial in preserving food and for medical applications. Aqueous, ethanolic and DMSO extracts were prepared from solid birch-bark tar and evaluated in vitro for the induction of DNA damage using Comet, micronucleus and sister-chromatid-exchange assays. Additionally, apoptosis induction was assessed. For the ethanolic extract, only the Comet assay showed a significant increase of DNA damage. All three extracts were able to significantly induce apoptosis. Thus, birch-bark tar seems capable of inducing genotoxic damage as well as apoptotic effects possibly originating from the triterpenoids’ antimicrobial properties. We examine why prehistoric tar is found with tooth marks, the beneficial effects of birch-bark tar, and evidence for increased genotoxic risk upon exposure.
Effect of Mulching on Uptake of Copper and Nickel from Smelter-Polluted-Soil by Planted Tree Seedlings  [PDF]
Eva Komanicka, Helj?-Sisko Helmisaari, Markus Hartman, Tiina M. Nieminen
Open Journal of Air Pollution (OJAP) , 2013, DOI: 10.4236/ojap.2013.23008
Abstract:

Our aim was to determine the long-term effect of a mulching treatment on copper (Cu) and nickel (Ni) uptake by tree seedlings (Pinus sylvestris L. and Betula pubescens Ehrh.) from smelter-polluted forest soil in southwesternFinland. A mulch cover spread onto polluted barren soil did not have a clear positive impact on the biomass production and it did not decrease metal uptake by planted tree seedlings during a ten-year study period. In contrast, the Cu uptake by the above-ground parts of birch was increased as a result of mulching, although there were weak indications of slightly reduced availability of Cu and Ni to roots in the case of both species. As Cu and Ni concentrations of foliage and bark have been shown to be strongly affected by surface deposited metal containing aerosols, only the woody compartments were used as indicators of metal uptake from soil. The Cu:Ni ratios of woody compartments were lower than those predicted by the Cu:Ni ratios of soil suggesting that the soil extraction method used gives an underestimation of available Ni in relation to Cu. The lower soil Niexch concentrations on the mulched plots compared to the controls were in agreement with the slightly lower root Ni concentrations in the mulch treatments.

Mitigating Biodiversity Concerns in Eucalyptus Plantations Located in South China  [PDF]
Roger A. Williams
Journal of Biosciences and Medicines (JBM) , 2015, DOI: 10.4236/jbm.2015.36001
Abstract:

China’s growing economy and changes in policies that encourage afforestation, particularly in the industrial sector, have led vast areas in south China to be planted with eucalyptus. These large areas of eucalyptus plantings have elicited environmental concerns for two primary reasons. First there is a concern related to the water demand of eucalyptus, in which it is feared these large areas of eucalyptus will deplete aquifers and create shortages in water supplies. The second concern is in regard to the reduction in biodiversity across large landscapes, leading to further ecological demises. This paper proposes two ideas to possibly mitigate some of the biodiversity concerns. The first is the interplanting of alder-leaf birch (Betula alnoides), a native but dwindling species in south China, to enhance biodiversity and encourage it’s reestablishment across the landscape. The second is to encourage retention harvests of alder-leaf birch planted within eucalyptus plantations to enhance not only biological diversity but also structural diversity across the landscape. Alder-leaf birch has demonstrated great potential in producing high quality timber and wood for use in furniture manufacturing.

Identifying Sustainable Practices for Tapping and Sap Collection from Birch Trees: Optimum Timing of Tapping Initiation and the Volume of Nonconductive Wood Associated with Taphole Wounds  [PDF]
Abby K. van den Berg, Mark L. Isselhardt, Timothy D. Perkins
Agricultural Sciences (AS) , 2018, DOI: 10.4236/as.2018.93018
Abstract: Experiments were conducted to determine two pieces of information essential to identify practices necessary to ensure tapping trees for birch sap collection is both sustainable and profitable—the selection of the time to initiate tapping birch trees to obtain maximum yields, and the volume of nonconductive wood (NCW) associated with taphole wounds in birch trees. The yields obtained from various timing treatments varied between sapflow seasons, but indicate that using test tapholes to choose the appropriate time to initiate tapping is likely to result in optimum yields from birch trees. The volume of NCW associated with taphole wounds in birch trees was highly variable and generally quite large, averaging 220 times the volume of the taphole drilled, and requiring relatively high radial growth rates to maintain NCW at sustainable levels over the long-term. However, more conservative tapping practices, including reduced taphole depth and increased dropline length, as well as thinning and other stand management practices, can be used to reduce the minimum growth rates required. Producers can use this information to ensure that they use tapping practices that will result in sustainable outcomes and obtain the maximum possible sap yields from their trees.
Respiration Rates of Organic Soil Depending on Changes of Moisture and Aeration  [PDF]
Zofia Fischer, Pavel Bla?ka, Lidya Dubis
Open Journal of Soil Science (OJSS) , 2017, DOI: 10.4236/ojss.2017.76008
Abstract: This paper aims at analyzing changes in soil respiration depending on the levels of soil moisture and aeration. Organic forest soil was used in the experiments. Watering of the soil was applied starting from two initial moisture contents: 1) GWC > 0.1, desiccated soil, respiration equals to zero; 2) GWC between 0.46 - 0.78, moisture of the soil approximately the same as at the time of sample collection. Watering of the soil was applied once or continuously during the experiment. The experiments were conducted under both: unrestricted air-supply and anoxic conditions. Measurements of: oxygen consumption, carbon dioxide emission, and RQ were determined with a volumetric respirometer. Soil desiccation, which occurs under good access of the air, and leads to the increase of respiration rate (the “Birch effect”), is predominantly related to aerobic respiration following the change in soil aeration. If respiration of non-desiccated soil is assumed as 100%, the oxygen consumption of desiccated soil equaled to 209.90% of such value in the non-desiccated soil at the lowest moisture level, and only to 51% at the highest. Carbon dioxide emission equaled to 191.92% and 111% at the lowest and the highest moisture levels, respectively. Desiccation did not increase the respiration rate under anoxic conditions. It either decreased or remained statistically unchanged. However, obtained values of RQ index suggest that under anoxic conditions desiccation affects fermentation processes in the soil. The value of RQ index at the moisture level lower than GWC 1 was very low attaining merely 0.3 - 0.4, which suggests active fermentation processes. At higher moisture content yet, RQ value exceeded 2.
Analysis of Airborne Betula Pollen in Finland; a 31-Year Perspective
Eija Yli-Panula,Desta Bey Fekedulegn,Brett James Green,Hanna Ranta
International Journal of Environmental Research and Public Health , 2009, DOI: 10.3390/ijerph6061706
Abstract: In this 31-year retrospective study, we examined the influence of meteorology on airborne Betula spp. (birch) pollen concentrations in Turku, Finland. The seasonal incidence of airborne birch pollen in Turku occurred over a brief period each year during spring (April 30 – May 31). Mean peak concentrations were restricted to May (May 5 to 13). Statistically significant increases in the annual accumulated birch pollen sum and daily maximum values were observed over the study period. Birch pollen counts collected in April were retrospectively shown to increase over the duration of the study. Increases in April temperature values were also significantly associated with the earlier onset of the birch pollen season. Furthermore, the number of days where daily birch pollen concentrations exceeded 10 and 1,000 grains/m3 also increased throughout the study period. These data demonstrate that increases in temperature, especially during months preceding the onset of the birch pollen season, favor preseason phenological development and pollen dispersal. Birch pollen derived from other geographical locations may also contribute to the aerospora of Turku, Finland. To date, the public health burden associated with personal exposure to elevated birch pollen loads remains unclear and is the focus of future epidemiological research.
Air pollution effects on the percentage of stomata in the leaves of tested species of horse chestnut and birch in Banja Luka conditions
Olja?a Rodoljub,Govedar Zoran,Hrki? Zoran
Glasnik ?umarskog Fakulteta , 2008, DOI: 10.2298/gsf0898155o
Abstract: The aim of this paper is the determination of air pollution influence on the percentage of stomata in tested woody species, horse chestnut and birch, under examined Banja Luka air pollution conditions. Two locations in Banja Luka town were examined, with different air pollution degrees: the first location is a hostel for students, with the minimal or absent air pollution; the second location is the west transit, with high air pollution due to a high number of motor cars which pass by the west transit. The air pollution difference between these two locations is very marked, and the objective of the examination was to assess how the indicated locations, which have different life conditions for the tested woody species, impact the physiological processes such as transpiration and photosynthesis. The study species react differently when the percentage of stomata and air pollution are compared.
Convergent syntheses of LeX analogues
An Wang,Jenifer Hendel,France-Isabelle Auzanneau
Beilstein Journal of Organic Chemistry , 2010, DOI: 10.3762/bjoc.6.17
Abstract: The synthesis of three Lex derivatives from one common protected trisaccharide is reported. These analogues will be used respectively for competitive binding experiments, conjugation to carrier proteins and immobilization on gold. An N-acetylglucosamine monosaccharide acceptor was first glycosylated at O-4 with a galactosyl imidate. This coupling was performed at 40 °C under excess of BF3·OEt2 activation and proceeded best if the acceptor carried a 6-chlorohexyl rather than a 6-azidohexyl aglycon. The 6-chlorohexyl disaccharide was then converted to an acceptor and submitted to fucosylation yielding the corresponding protected 6-chlorohexyl Lex trisaccharide. This protected trisaccharide was used as a precursor to the 6-azidohexyl, 6-acetylthiohexyl and 6-benzylthiohexyl trisaccharide analogues which were obtained in excellent yields (70–95%). In turn, we describe the deprotection of these intermediates in one single step using dissolving metal conditions. Under these conditions, the 6-chlorohexyl and 6-azidohexyl intermediates led respectively to the n-hexyl and 6-aminohexyl trisaccharide targets. Unexpectedly, the 6-acetylthiohexyl analogue underwent desulfurization and gave the n-hexyl glycoside product, whereas the 6-benzylthiohexyl analogue gave the desired disulfide trisaccharide dimer. This study constitutes a particularly efficient and convergent preparation of these three Lex analogues.
第1页/共65条
每页显示


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.