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排序方式: 共有200条查询结果,搜索用时 15 毫秒
1.
随着经济发展和人们生活水平的提高,人们开始追求更加健康的生活方式,对家具产品的要求越来越高。近年来,俄勒冈硬木由于其良好的装饰性能,较弱的导热性,优良的耐水性、耐高温性、耐腐蚀性和易于清洁性,已成为家具产品的重要原料,在家具制造中有着广阔的发展前景。重点介绍俄勒冈硬木的耐水性,安全性和装饰性,研究俄勒冈硬木在家具生产应用中的可行性。通过讨论俄勒冈硬木在家具设计中的应用,对于改善人性化设计方案和提高市场占有率提出一些建议。 相似文献
2.
以3个树种健康复叶为试材,研究了叶内光合构件和支撑构件的生物量投资的种内种间变化规律。结果表明:水曲柳、胡桃楸和黄檗叶轴质量占复叶质量的比例分别为0.18、0.26和0.17,胡桃楸显著大于其它2个树种。跨物种尺度上,复叶大的树种需要更多的叶内支撑结构投资。但物种水平上,水曲柳叶片投资随叶增大而增大,胡桃楸则降低,黄檗基本稳定,表现出与跨物种水平上的叶片投资随叶增大而降低的普遍规律不同。今后需要加深物种水平上叶内生物量分配的异速生长的了解。 相似文献
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4.
Esteban R. Suárez Geraldine L. Tierney Timothy J. Fahey Robert Fahey 《Landscape Ecology》2006,21(2):297-306
Exotic earthworms invading forests in Canada and northeastern United States that were naturally devoid of large detritivores
cause major changes in ecosystem function. To assess their long-term impacts, studies are needed to elucidate the factors
that control the patterns of earthworm invasion at the landscape level. We analyzed the distribution patterns of exotic earthworms
in a northern hardwood forest in south-central New York (USA), as explained by landscape variables thought to be important
in determining earthworm distribution. Forest type, slope angle, elevation, and the distance to agricultural clearings and
wet refugia were significant predictors of earthworm presence, whereas local wetness index and the distance to streams and
roads were not. Forest type and distance to agricultural clearings were the two most significant predictors. Our data suggest
that areas close to agricultural clearings, dominated by mixed hardwoods, and located towards valley bottoms or on gentle
slopes are very likely to support communities of exotic earthworms. Steeper slopes, areas dominated by American beech or eastern
hemlock, and locations in the core of extensive forest landscapes have lower probabilities of invasion by exotic earthworms.
When applied to a nearby area, our statistical model correctly predicted earthworm presence for 67% of 377 sampling points.
Most of the mistakes were incorrect predictions of earthworm absence, suggesting that our statistical model slightly underestimated
earthworm presence, possibly because of the pervasive influence of active agricultural fields adjacent to the test site. 相似文献
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Algarrobo (Prosopis alba) is an important nitrogen-fixing tree adapted to the semiarid regions of northwestern Argentina. The tree provides fuelwood and dimensionally stable lumber for flooring and furniture; its pods that have a high sugar content are consumed by livestock and humans. P. alba has been one of the most heavily harvested species. This paper reports on the evaluation of a nine-year-old Prosopis alba progeny trial containing 57 half-sibling families of eight provenances in northwestern Argentina (of the 1,596 trees planted, 1,289 survived in 1999). Considering the multiple uses of P. alba, the selection criteria included: total biomass production (from basal diameter using regression equations), height, rate of pod production, and pod sensory characteristics. The family-narrow-sense-heritability was 0.487 for height. 0.548 for biomass production, and 0.244 for pod production. In 1998, 12 of the 1,289 trees were more than 4 m tall and had more than 1.75 kg pods per tree; and their pods had a sweet or very sweet non-astringent taste. Scions from these 12 trees were successfully grafted onto unselected P. alba rootstock. These are currently being used to produce rooted cuttings. The pod production, biomass, and height of the 12 clones ranged from 6.55 to 14.4, 1.57 to 13.5, and 1.29 to 1.70 times the respective population means. The genetic gains of 13.5%, 77%, and 147% for height, biomass, and pod production respectively are greater than genetic gains for other tree species and are probably due to the great genetic variability in the local population and the lack of any prior genetic improvement program.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
7.
Survival of tanoak (Lithocarpus densiflorus) and Pacific madrone (Arbutus menziesii) seedlings was studied in order to interpret succession in conifer hardwood forests and to determine ways to suppress establishment of these species. Seed protected from rodents and birds, and unprotected seed was sown in clearcuts and in conifer stands 40 to 200+ years old. Second-year survival rates of tanoak seedlings were high (50–70%) in exposed clearcuts and conifer stands. Seed predators appear to be of prime importance in limiting tanoak establishment. Survival rates of Pacific madrone seedlings on the same sites as the tanoak were low (0–8%), and many factors caused mortality. Seedlings of both species grew slowly; after 3 years, average tanoak height was only 6.0 to 14.0 cm, average madrone height 2.0 to 6.0 cm. 相似文献
8.
我国50~60年代初期,林业部综合队曾编制红松(Pinus koraiensis Sieb.et Zucc.)、云杉(Picea spp.)、马尾松(Pinus massoniana Lamb.)、兴安落叶松(Larix gmelini(Rupr.)Rupr.)、白桦(Betula platyphylla Suk.)等树种材种出材量表,70~80年代各省(区)市、规划院、科研等单位对杉(Cunninghamia lanceolata Hook.)、落叶松、山杨(Populus davidiana 相似文献
9.
Charalampos Lykidis Athanasios Grigoriou Ioannis Barboutis 《Wood material science & engineering》2014,9(4):202-208
This paper investigates the potential of utilising wood biomass from fruit tree branches and evergreen hardwood shrubs as raw materials in the production of particleboards when mixed with Greek fir wood particles. The main mechanical properties of the boards made therefrom were determined and compared with those made of typical industrial wood (IW) particles. The highest modulus of rupture and elasticity (30.0 N/mm2 and 4330 N/mm2, respectively) in bending and screw withdrawal (SW) resistance (127.8 N/mm) were reported for boards made of Greek fir and were downgraded when the fruit tree branches or evergreen hardwood shrub particles also participated. The participation of fruit tree branch particles in proportions higher than 50% improved the internal bond (IB) of fir produced boards, while the highest IB strength (0.95 N/mm2) was reported for boards made of fruit tree branches. Particleboards made of evergreen hardwood shrubs showed inferior mechanical properties compared with those made of IW particles. The latter also showed superior bending strength but inferior SW resistance compared with boards made of fruit tree branches. Hygroscopic and other properties are under determination and will be presented and discussed in the second part of the work. 相似文献
10.
为探寻电热温床催根的生理和分子生物学机制,以无花果一年生枝为材料,筛选与电热温床处理促生根效果近似的吲哚丁酸(IBA)处理条件,比较插条生根过程中主要内源激素水平的变化。结果表明:500mg/L IBA浸泡插条基部与2h与28℃电热温床处理12d的促生根效果相似。插条基部组织激素水平测定显示,IBA和电热温床处理均能在处理开始后0~10d快速而显著地提高样品中吲哚丁酸(IAA)和玉米素(ZR)的浓度;与IBA处理相比,电热温床处理显著提高了早期样品中的脱落酸(ABA)浓度;不同处理和对照样品中的赤霉素(GA)含量在0~10d差别不大,后期以IBA处理的样品中的GA含量最高。研究结果显示在启动硬枝扦插生根的激素响应模式上,电热温床和IBA处理既有共同点,又存在独特性。 相似文献