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1.
Thermogravimetric and differential thermal analyses techniques have been applied to investigate the thermal degradation characteristics
and chemical kinetics of Japanese cedar, cypress, fir, and spruce. The decomposition of the components could be modeled by
an Arrhenius kinetic expression. The kinetic parameters were extracted from the thermogravimetric data using least-squares
techniques. The heating rates used for the analyses were 10°, 5°, and 0.33°C/min; and the activation energy and reaction order
of the above woods were 7.54, 8.39, 2.87, and 7.88 kJ/mol and 0.71, 0.64, 0.44, and 0.63, respectively. Finally, carbonization
was done to produce charcoal from these woods under various operating conditions, and the charcoal was characterized in respect
to yield, heating value, electrical conductivity, and X-ray diffraction. The quality of the charcoal from fir was the best
among the four types of wood. The charcoal produced is inferior to binchotan (white charcoal) in respect to electrical conductivity
and crystalline structure.
Received: February 13, 2002 / Accepted: July 12, 2002
Acknowledgment The authors express their gratitude to Professor Yoshida of Applied Chemistry in Tokyo Metropolitan University for performing
the TG/DTA in his laboratory and for his valuable suggestions about the analyses. 相似文献
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Sasa Sofyan Munawar Kenji Umemura Fumio Tanaka Shuichi Kawai 《Journal of Wood Science》2008,54(1):28-35
This study focused on the effects of treatments of alkali, mild steam, and chitosan on the surface morphology, fiber texture,
and tensile properties of pineapple, ramie, and sansevieria fiber bundles. The fibers were treated with NaOH (2%), mild steam
(0.1 MPa), and chitosan solutions (4% and 8%). The properties of these treated fibers were characterized and compared with
the untreated fibers. Field emission scanning electron microscopy (FE-SEM) was used to observe the surface morphology of those
fibers. X-Ray diffraction (XRD) spectroscopy was used to observe the fiber textures. Tensile properties of the treated and
untreated fibers were also recorded. SEM micrographs showed that the surfaces of the NaOH-treated fibers were more damaged
than those of the steam-treated fibers. The 4% chitosan solution covered the fiber surface more uniformly than the 8% chitosan
solution. The steam-treated fibers had higher values of degree of crystallinity, crystallite orientation factor, and crystallite
size than the NaOHtreated fibers. Ramie fiber showed greater mechanical properties than the other fibers. The values of tensile
strength, Young’s modulus, and toughness of the steamtreated fibers, which were similar to those of the 4% chitosan-coated
fibers, were higher than those for the other treatments. 相似文献
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We address the question of how credible knowledge that will contribute to more effective forest policy and management can
be produced. We argue that some forest-related knowledge-producing practices of professional scientists and of local people
are similar, and given the differences in the knowledge they produce, we explore how they might be used productively together
to create better understandings of forests with resulting better forestry practice and policy. Using a case study of participatory
forest ecology research, we demonstrate that when professional (conventional) scientists do research in collaboration with
local experts (civil scientists), the resulting knowledge can be more accurate and more policy relevant than they could produce
doing research on their own or only with other conventional scientists. 相似文献
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本文就核桃采收时间、脱皮方法及坚果分级标准进行了初步研究总结,为实现核桃优果优价、提质增效提供了切实可行的理论依据。 相似文献
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Behavioral responses,rate of mortality,and oviposition of western cherry fruit fly exposed to malathion,zeta-cypermethrin,and spinetoram 总被引：1，自引：1，他引：0
Western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is a pest of sweet and tart cherry, Prunus avium L. (L.) and P. cerasus L., respectively, in western North America. This fly is commonly controlled with spinosad bait sprays. Spotted wing drosophila,
Drosophila suzukii Matsumura, is potentially a new pest of cherries in this region that could be a threat to orchards at the same time as R. indifferens. Drosophila suzukii apparently is not controlled using spinosad bait sprays, but may potentially be controlled using malathion, zeta-cypermethrin,
and spinetoram. However, how well these last three materials protect fruit against reproductively mature R. indifferens is not known. In laboratory observations, R. indifferens spent the least amount of time on cherries treated with zeta-cypermethrin, possibly because of its toxicity and irritant
effects. In laboratory experiments, zeta-cypermethrin killed flies more quickly than malathion and spinetoram, causing up
to 100% mortality 2 h after exposure. Zeta-cypermethrin prevented all oviposition when flies walked on dried residues for
20–25 min or were directly sprayed, and then exposed to cherries with dried residues, simulating exposure of mature female
flies in a treated orchard. Malathion and spinetoram reduced oviposition compared with controls, but did not prevent it, when
flies contacted residues or were directly sprayed at a high volume. Results suggest zeta-cypermethrin is the most effective
of the three materials at protecting cherries against mature R. indifferens and could be used in an integrated control program for it and D. suzukii. 相似文献
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林地土壤pH值，磷，钾，有机质和水含量具有可变和可控性 总被引：1，自引：0，他引：1
对取自山西省北部不同地点、不同层次的土样的pH值、磷、钾、有机质、水含量的变化进行了研究。结果表明：林地土壤理化性质具有可变性的可控性。 相似文献
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Lewis Clifford E. Burton Glenn W. Monson Warren G. McCormick W. C. 《Agroforestry Systems》1983,1(4):277-297
Agroforestry Systems - Native forages of southern United States are frequently low in nutrients and poorly digestible, while improved pastures are the opposite. Since this area produces rapid... 相似文献
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Seedling emergence, growth, and allocation of Oriental bittersweet: effects of seed input, seed bank, and forest floor litter 总被引：3，自引：0，他引：3
Joshua W. Ellsworth Robin A. Harrington James H. Fownes 《Forest Ecology and Management》2004,190(2-3):255-264
The establishment of invasive plant populations is controlled by seed input, survival in the soil seed bank, and effects of soil surface disturbance on emergence, growth, and survival. We studied the invasive vine Celastrus orbiculatus Thunb. (Oriental bittersweet) to determine if seedlings in forest understory germinate from the seed bank or from seed rain. We also conducted a greenhouse experiment to investigate the role of leaf litter mass and physical texture on seedling survival, growth, and allocation. In the understory of an invaded mixed hardwood forest, we measured seed input, seedling emergence with seed rain, and seedling emergence without seed rain. Mean seed rain was 168 seeds m−2: mean seedling emergence was 107 m−2, and there was a strong correlation between seed rain and seedling emergence. The ratio of seedlings to seed input (0.61) was close to the seed viability (0.66) leaving very few seeds to enter the seed bank. Seed bank germination under field conditions was low (1 seedling m−2). Soil cores were incubated in a greenhouse to determine seed bank viability, and germination from these soil cores did not occur. To determine how litter affects seedling establishment and growth, we measured seedling emergence and biomass allocation in a greenhouse experiment. Seeds were placed below intact and fragmented deciduous leaf litter in amounts ranging from zero to the equivalent of 16 Mg ha−1. Seedling emergence was not affected by fragmented litter, but decreased to <20% as intact litter increased to 16 Mg ha−1. Increasing litter resulted in greater allocation to hypocotyl and less to cotyledon and radicle, and this effect was greater in intact litter. C. orbiculatus seedlings achieve emergence through forest floor litter through plasticity in allocation to hypocotyl growth. The low survival of C. orbiculatus in the seed bank suggests that eradication of seedling advance regeneration and adult plants prior to seed rain may be an effective control strategy. However, the intact forest floor litter of an undisturbed forest will not prevent seedling establishment. 相似文献
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This study presents data on the biomass and net aerial primaryproductivity (NAPP) of two contrasting East Anglian salt marshes.One site was at Tollesbury, Essex where the marshes are of theestuarine type and are subject to marsh degradation and erosionwhile the other site was 130 km to the north at Stiffkey, Norfolkwhere the barrier-type marshes are still actively developing withno signs of erosion. The NAPP was determined by the method ofSmalley with quadrats being harvested monthly with replacement.At the lowest levels at Tollesbury there was Pioneer Marshwhich was dominated by a mixture of Salicornia spp. and Astertripolium. At higher levels at Tollesbury there was LowerMarsh which was dominated by a mixture of Atriplex portulacoides andPuccinellia maritima. Over the four years of the studyPuccinellia became the dominant species following a markeddecrease in the extent and vigour of Atriplex. At Stiffkey theMiddle Marsh was at a much higher level and the vegetation waspredominantly a short dense sward with Atriplex portulacoides,Puccinellia maritima and Limonium vulgare together with smallerquantities of Armeria maritima and Plantago maritima. The meanNAPPs over three years of the Pioneer and Lower Marsh atTollesbury (467 & 519 g m-2 yr-1respectively) were similar butin 1993 the NAPPs recorded at Tollesbury were higher than thoserecorded at Stiffkey (625 & 583 compared with 458 g m-2yr-1).Smalleys method is difficult to apply to communities wherespecies dominance is variable, especially when dominance isshared between species with markedly different growth patterns.The results for NAPP obtained from the salt marshes at Tollesburyand Stiffkey are discussed in relation to results obtained byother workers from comparable areas in England and theNetherlands. Attention is also drawn to the possibly largerbelow-ground component of production that is frequentlyoverlooked. The importance of salt marshes in relation to othercoastal communities lies in the export of a proportion of theorganic matter produced and this mainly depends on theabove-ground production. 相似文献
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Stewart A.W. Diemont Jessica L. BohnDonald D. Rayome Sarah J. KelsenKaity Cheng 《Forest Ecology and Management》2011,261(10):1696-1705
Numerous communities associated with at least five distinct ethnic Mayan groups in southern Mexico and Central America continue to rely upon forested areas as integral components of their agricultural systems. They carefully manage these areas so that forests provide food, raw materials, and animals. Management practices include removing and planting of woody and herbaceous species, apiculture, and seed harvest. Mayan agroforestry systems in geographically and ecologically distinct areas of Mesoamerica were evaluated to better understand traditional agroforestry system components and how indigenous Mayan agroforestry could be a part of regional forest conservation and restoration. Systems were within Mexican land grant areas (ejidos) or on contested land. Although these systems rely upon different woody species and management techniques, common among them are: (1) the use of multi-stage and successional pathways with forest as a part of the larger system, (2) species that are believed by traditional ecological knowledge (TEK) to accelerate forest regeneration - more than 30 tree species are recognized and managed as potential facilitators of forest regeneration and (3) direct human consumption of forest products at all stages of regeneration. 相似文献
13.
《Forest Ecology and Management》1999,124(1):45-77
Tree growth, biomass productivity, litterfall mass and nutrient content, changes in soil chemical properties and understory forest succession were evaluated over a 8.5-year period in single- and mixed-species (50 : 50) plantations of two N2-fixing species, Casuarina equisetifolia and Leucaena leucocephala, and a non-fixing species, Eucalyptus robusta. At the optimal harvest age for maximum biomass production (4 years), total aboveground biomass ranged from 63 Mg ha−1 in the Eucalyptus monoculture to 124 Mg ha−1 in the Casuarina/Leucaena mixture, and was generally greater in the mixed-species than in single-species treatments due to increased productivity of the N-fixing species in the mixed stands. Total litterfall varied from 5.3 to 10.0 Mg ha−1 year−1 among treatments, or between 5.9% and 13.2% of net primary production. Litterfall production and rates of nutrient return for N, P, K, Ca and Mg were generally highest for Leucaena, intermediate for Casuarina and lowest for Eucalyptus. These rates were usually higher in the mixed-species than in monospecific stands due to differences in biomass productivity, but varied considerably depending on their species composition. Total system carbon and nutrient pools (in biomass plus soils to 40-cm depth) for N, P, K, Ca, Mg, Mn at four years were consistently greater in the plantation treatments than in the unplanted control plots. Relative to the single-species plantations, these system pools were generally larger in the mixed-species plantations for C (−10% to +10%), N (+17% to +50%), P (−1% to +63%), K (−19% to +46%), Ca (−10% to +48%), Mg (+5% to +57%) and Mn (+19% to +86%). Whole-tree harvests at four years would result in substantial system carbon and nutrient losses, although these estimated losses would not exceed the estimated gains realized during the four-year period of tree growth at this site. At 7.5 years, soil organic matter and effective cation exchange capacity were reduced in all plantation treatments relative to the control. Changes in soil nutrient content from 0 to 7.5 years were highly variable and not significantly different among treatments, although stands containing Leucaena generally showed higher rates of nitrogen and phosphorus accretion in soils than those with Eucalyptus and/or Casuarina. Natural regeneration of secondary forest tree and shrub species increased over time in all plantation treatments. A total of 24 native or naturalized forest species were recorded in the plantations at 8.5 years. Woody species abundance at this age was significantly greater beneath Casuarina than either Eucalyptus or the Eucalyptus/Leucaena mixed stands. Species richness and diversity, however, were greatest beneath stands containing Eucalyptus and/or Leucaena than in stands with Casuarina. 相似文献
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Effects of stratification, desiccation, radicle pruning, and season of sowing on Quercus vulcanica germination and growth were studied to identify optimum nursery procedures for artificial regeneration of this species. Following stratification (0, 2, 4 and 8 weeks), acorns were germinated, and acorn moisture content and germination performance were also determined at various times during desiccation. In early December unsprouted acorns were planted in containers, and in early April sprouted acorns, which had been stored in polyethylene bags at 4 °C, with radicles left intact or with radicles pruned back to 1.0 cm were planted in containers.Stratification for 2 and 4 weeks did not increase germination percentage but significantly increased germination rate. Germination percentage of the seeds dropped when the moisture content of the seeds was reduced by desiccation, and the critical minimum moisture content of the recalcitrant Q. vulcanica acorns was found to be 11–16%. Spring sowing of sprouted acorns altered the morphology the containerized seedlings and caused the formation of significantly more main roots, but resulted in significantly less shoot height and shoot dry weight. Spring-sown sprouted acorns had also a significant advantage over the fall-sown unsprouted acorns in seedling survival, and thus nursery personnel should not be concerned if acorns sprout before sowing. 相似文献
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Key message
This paper briefly reviews the state of the art in various types of wood- and bio-based composites, summarizes recent advances, and then discusses future possibilities for improving the durability of wood- and bio-based composites.Context
Wood can be processed and reformed into a number of different biocomposites.Aims
We aimed at reviewing the state of the art in various types of wood- and bio-based composites.Methods
Review of utility, performance and durability of wood- and bio-based composites.Results
The advanced biocomposites will:Combine wood, natural biofibers, and non-biomaterials to create synergistic hybrid materials that far exceed performance capabilities of current biocompositesBe renewable, recyclable, and totally sustainableProvide superior performance and serviceability exceeding performance of current biocompositesBe more durable, dimensionally stable, moisture proof, and fire resistantBe less expensive to produce and use (over the life cycle of use) than the materials they replaceConclusion
The next generation of advanced wood- and bio-based composites must provide high-performance construction and specialty products that simultaneously promote resource and environmental sustainability and provide advanced performance, long-term performance, enhanced durability, and value.19.
草炭及其改良土壤对氮、磷、钾的吸附特性 总被引：2，自引：0，他引：2
以草炭、壤土、砂土为试材,研究其在恒温条件下对氮、磷、钾的吸附特征,并筛选最佳模型来拟合各吸附等温线.结果表明:草炭对氮、磷的保肥能力较强,对钾的保肥能力极弱;增施草炭后,有助于提高不同土壤载体对氮和磷的保持能力,对钾的保肥能力无明显提高;用3种不同模型拟合,发现Freundlich与Temkin模型可以很好拟合铵离子吸附等温线,磷、钾的吸附等温线用Freundlich模型拟合效果较好,线形方程拟合草炭吸附铵的效果最好(R2=0.99). 相似文献
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Growth, nutrition, photosynthesis and transpiration responses of longleaf pine seedlings to light, water and nitrogen 总被引：15，自引：0，他引：15
Early growth and physiology of longleaf pine (Pinus palustris Mill.) seedlings were studied in response to light, water and nitrogen under greenhouse conditions. The experiment was conducted with 1-year-old seedlings grown in 11.3 l pots. The experimental design was a split-plot factorial with two levels (low and high) of each of the factors, replicated in three blocks. The four factorial combinations of water and nitrogen were randomly applied to 15 pots (sub-plots) in each of the light treatment (main plot). Data were collected on survival, root collar diameter (RCD), and height on a monthly basis. Biomass (shoot, root and needle), leaf area index, specific needle area, and needle nutrient (N, P, K, Ca, and Mg) concentrations were determined following final harvest after 16 months. Physiological data (net photosynthesis and transpiration) were collected monthly from March to July during the second growing season.
Height and RCD were significantly influenced by nitrogen and water and by the interaction between them with no apparent effect of light. Seedlings grew 93% taller in the high nitrogen and well watered (HNWW) treatment compared to the low nitrogen and water stressed (LNWS) treatment. Similarly, a significant increase (78%) in RCD was observed for seedlings in the HNWW treatment over the LNWS treatment. Light, along with water and nitrogen, played an important role in seedling biomass growth, especially when water was not limiting. Biomass partitioning (as measured by root:shoot ratio) was affected only by nitrogen and water. Nutrient stress had a greater influence on carbon allocation (69% increase in root:shoot ratio) than water stress (19% increase). Net photosynthesis (Pnet) was significantly higher for seedlings in the high resource than in the low resource treatments with significant light×water and nitrogen×water interactions. Transpiration rate was higher (75%) under the WW treatment compared to the WS treatment. Longleaf pine seedlings grown under the LNWW treatment had the lowest foliar nitrogen (0.71%) whereas seedlings in the HNWS treatment had the highest (1.46%). Increasing the availability of light (through larger canopy openings or controlling midstory density) and soil nitrogen (through fertilization) may not result in greater Pnet and improved seedling growth unless soil water is not limiting. 相似文献