共查询到20条相似文献，搜索用时 125 毫秒
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简要阐述了森林在社会及经济发展中的重要作用,并分析了森林火灾的危害性及森林防火在林业中的重要地位,人们往往存在重造林轻预防的落后思想。提出了森林防火应以人为本,提高全民预防森林火灾意识,强化森林防火队伍建设,全面落实森林防火责任制,加强预警监测工作,切实提高森林火灾监控能力,并着力完善森林防火基础设施建设,因地制宜建立乡镇联防体系,运用现有科技手段为森林防火服务,保护好森林资源和人民群众生命财产安全,保障地方经济发展、社会和谐稳定做出贡献。 相似文献
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针对南方集体林权制度改革后,森林防火责任主体的变化情况,结合湖南实际,分析了林改后经营主体森林经营积极性提高,但防火减灾意识不强,能力不足的状况,认为需要从强化林权主体森林防火责任,引导经营业主建立森林防火协会组织,增强其自救能力。并从继续发挥现有由政府主导的森林防火体系的公共服务功能等方面着手,建立一种兼顾公共利益与经营业主利益的森林防火资金投入和预防、预警、处置机制。同时,在森林火灾预警、扑救以及减少林区生产用火等技术体系上加大投入和开发力度,借助现代空间技术、计算机技术等成果,提高总揽森林火险全局的能力。还需降低林区生产性和生活性用火机会,改变用火方式,提高森林火灾预防和灾后重建能力。 相似文献
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Various effects of four different thinning treatments, aftera period of 44 years, are outlined and discussed. In particular,there was found to be no significant difference between C, D,and LC grades in total volume production. The D grade thinningis shown to be the most favourable from an economic viewpoint. 相似文献
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Sung-Jun Pang Jung-Kwon Oh Jung-Pyo Hong Sang-Joon Lee Jun-Jae Lee 《Journal of Wood Science》2018,64(2):126-137
The aim of this study was to develop a stochastic model for predicting the bending strength distribution of glued-laminated timber (GLT). The developed model required the localized modulus of elasticity (MOE) and tensile strengths of laminae as input properties. The tensile strength was estimated using a regression model based on the localized MOEs and knot area ratios (KAR) which were experimentally measured for lamina grades samples. The localized MOE was obtained using a machine stress-rated grader, and the localized KAR was determined using an image-processing system. The bending strength distributions in four types of GLTs were simulated using the developed GLT beam model; these four types included: (1) GLT beams without finger joints; (2) GLT beams with finger joints; (3) GLT beams with different lamina sizes; and (4) GLT beams with different combinations of lamina grades. The simulated bending strength distributions were compared with actual test data of 2.4 and 4.8 m-long GLTs. The Kolmogorov–Smirnov goodness-of-fit tests showed that all of the simulated bending strength distributions agreed well with the test data. Especially, good agreement was shown in the fifth percentile point estimate of bending strength with the difference of approximately 1%. 相似文献
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Existing log grading procedures in the United States make only visual assessments of log quality. These procedures do not incorporate estimates of the modulus of elasticity (MOE) of logs. It is questionable whether the visual grading procedures currently used for logs adequately assess the potential quality of structural products manufactured from them, especially those for which MOE is of primary concern. The purpose of this study was to investigate the use of stress wave nondestructive evaluation techniques to sort red maple logs for the potential quality of lumber obtained from them. Ninety-five red maple logs were nondestructively evaluated using longitudinal stress wave techniques and sorted into four stress wave grades. The logs were then sawn into cants and lumber. The same procedure was used to obtain stress wave times in the cants and lumber. The lumber specimens were then dried and graded using a transverse vibration technique. The results of this study showed that good relationships existed between stress wave times measured in logs, cants, and the lumber produced from the logs. It was found that log stress wave grades have positive relationships with the lumber grades. Logs with high stress wave grades produced high-grade lumber. These findings indicate that the longitudinal stress wave technique has potential in sorting logs and cants for the production of high MOE products.The Forest Products Laboratory is maintained in cooperation with the University of Wisconsin. This article was written and prepared by U.S. Government employees on official time, and it is therefore in the public domain and not subject to copyright. 相似文献
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橡胶树寒害气象等级研究 总被引：4，自引：1，他引：3
用我国云南、海南、广东三省主要橡胶种植区内11个气象站建站的2008年11月至次年3月逐日气象资料以及橡胶寒害灾情史料,开展橡胶树寒害等级的研究,为规范橡胶树寒害调查、统计和评估业务提供参考。根据橡胶树寒害的特点,提出橡胶树平流型低温天气过程、辐射型低温天气过程的概念,给出了橡胶树平流型寒害、辐射型寒害和混合型寒害的明确定义,并用极端最低气温、最大降温幅度、寒害持续日数、辐射型积寒、平流型积寒和最长平流寒害过程的持续日数共6个致灾因子,构建寒害指数。依据寒害指数的大小,将橡胶树寒害分为轻度、中度、重度、特重四个等级。同时给出了橡胶树遭受不同寒害等级时可能导致的橡胶干胶减产率和橡胶树受害率的参考值。 相似文献
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基于生态系统可持续发展理论,构建了由社会、经济、自然环境和自然灾害4个子系统和28个2级指标组成的湿地生态环境质量评价指标体系;以信息熵理论为基础建立了客观确定权重的综合信息熵模型,层次分析法和综合信息熵模型法相结合确定指标权重;采用灰色关联模型对湖南省重要湿地2002~2006年生态环境质量进行评价。结果表明:湖南省重要湿地生态环境质量整体上属中等水平;洞庭湖、官庄、青山垅湿地综合评价值较低,生态环境质量较差;涔天河、酒埠江、黄石、凤滩、铁山生态环境质量为中等;东江湖、双牌和柘溪湿地生态环境质量始终处在良好水平。 相似文献
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对贵州息烽林场６７个森林火险调查样方进行ＰＣＡ、ＣＯＡ排序和模糊综合评判表明：海拔影响林场森林可燃物分布状况和土壤含水量;林场森林火险以危险和较危险两级为主,影响的主要因素是海拔、森林可燃物类型和火源状况;森林可燃物分为非林分型可燃物,林相整齐的中幼林型可燃物和近成过熟林型可燃物、林相不整齐林分型可燃物;林场森林型可燃物和近成熟林型可燃物、林相不整齐林分型可燃;林场森林火险区划为４级区域,即很危险区（Ⅰ）、危险区（Ⅱ）、较危险区（Ⅲ）和略危险区（Ⅳ）。 相似文献
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The sixteen one-chain-square plots replicated four times werelaid out in the form of a latin square in 1930 in a denselystocked 20-year-old plantation with just over 3,000 stems peracre to study the effect of four thinning grades. Following up Hummel's 1947 paper (Forestry 21, 30), the authorgives figures for stems per acre, height, girth increment, basalarea, volume, and crown measurements up to 1960. 相似文献