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绥中县位于辽宁省西部,辽西走廊之西端。地理位置处于东经119°36’—120°30＇,北纬39°59＇—40°42＇。全县地势西北高,东南低,西北由海拔近4m的山地逐渐为200～300m的丘陵,到渤海沿岸则为海拔50m以下的滨海平原。总面积为412.5万亩,其中森林面积109万亩,森林覆盖率28.1％。森林火灾是森林的大敌,一点星星之火可将多年的绿化成果毁于一旦,给国家和群众造成重大损失。据统计,1979—1985年上半年,全县就发生林火56次,年均8.6次,其中成灾的18次,年均2.8次,燃烧面积达3294亩,年均506亩,烧林地面积1087亩,年均167亩。本文试图就我县林火与某 相似文献
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为评价内蒙古毕拉河林场2017年5月2日发生的森林火灾损失情况,利用火灾发生前后的Landsat8卫星影像,计算得到两者间的差值归一化燃烧指数(d NBR),通过目视解译和数学统计相结合的方法构建森林火灾受害程度分级评价指标,对该火烧迹地受灾程度进行定量评价,并利用实地测量GPS数据和GF-2卫星数据验证受害程度的分级精度为86.39%。研究结果表明:内蒙古毕拉河林场火烧迹地的中度受害区域面积最大,为4 685.09hm~2,占火烧迹地总面积的40.35%;轻度受害面积次之,为4 213.1hm~2,占火烧迹地总面积的36.28%;重度受害面积为1 031.03hm~2,占总面积的8.88%;未受害区域的面积最小为906.57hm~2,占火烧迹地总面积的7.81%;火烧迹地内的受灾森林主要分布在中度受害区域和轻度受害区域,受灾草地主要分布在轻度受害区域。 相似文献
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以研究大尺度范围内森林火灾面积提取的可行性为目的。本文以昆明市为研究区,分别提取2005年和2006年两期Landsat TM影像的植被指数、水体指数、火烧迹地指数、纹理特征等,并选取适于大尺度范围的最佳特征波段;利用特征融合后的影像构建决策树,实现大尺度范围内火烧迹地的自动提取。研究表明,QUEST算法的分类总体精度达84.5%,在3种分类方法中精度最高;采用QUEST算法的决策树分类提取"3·29"火烧迹地面积占实际的97.9%,但大尺度范围内火烧迹地提取效果并不理想,仍需人工剔除提取产生的较小的斑块;最后用2015年"3·02"的火烧迹地验证了QUEST决策树方法的具有一定的普适性。该模式对大尺度范围内森林火灾面积统计的具有重要应用价值。 相似文献
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大兴安岭林火迹地景观变化研究 总被引：3，自引：0，他引：3
大兴安岭地区是中国非常重要的林区,也是容易发生林火的地区。1987年6月5日发生的一场大火,使1.33?06公顷原始森林被毁,并产生了不同火烧强度的森林景观斑块。本文以图强林业局的两个林场作为典型区(124°05′-122°18′E,53°34′-52°15′N),通过绘制和比较1987年和2000年数字化的森林组分图,分析了火后森林景观的变化情况。本文将森林覆被类型分为12类,针叶林、阔叶林、针阔混交林、灌木、苗圃、采伐迹地、火烧迹地、农用地、沼泽、水域、建筑用地和荒草地。通过研究,得出以下结论:1)林火迹地已几乎全部演替为其他森林景观类型,林火迹地主要是通过自然演替成为阔叶林,其次是通过人工演替成为针叶林,其余的则大部分演替为沼泽和荒草地。2)研究区森林覆盖率由1987年的47.6%变为2000年的81.3%。为了今后林业可持续发展与管理,本文提出了加强防火意识和注重树种多样性培育等对策。图3表3参11。 相似文献
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廖显宗 《林业机械与木工设备》1980,(4)
目前加拿大年采伐量为1.27亿立米,估计到二十世纪初年采伐量将达2.15立米,接近于年允许采伐量2.41亿米的指标。为增加森林资源,加拿大对全部采伐迹地和火烧迹地进行更新,现在年采伐面积约91万公顷,森林火灾损失几乎同样 相似文献
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大兴安岭盘中林场火烧迹地森林恢复的对策 总被引：3，自引：0，他引：3
“5、6”特大森林火灾发生后,解决火烧迹地森林恢复问题已成为当务之急,现据1937年大兴安岭林管局林业调查规划院完成的二类资源清查数据,就重度火烧迹地盘中林场的森林恢复问题剖析如下。一、火烧区概况盘中林场位于大兴安岭北坡,塔河县境内。全场过火面积90313公顷,占总面积的 相似文献
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松材线虫染病黑松上钻蛀性昆虫生态位的研究 总被引：2，自引：0，他引：2
2006年8月和10月,在浙江省舟山市和安徽省滁州市的松材线虫病典型发生区调查了黑松上的钻蛀性害虫的种类,分析了衰弱木上优势虫种的生态位宽度、生态位相似性和生态位重叠值。结果表明:在感染松材线虫病的黑松上共发现7种昆虫,其中钻蛀类害虫5种,天敌2种。在两地生活于松树主干上的昆虫种类不尽相同,而且具有各自不同的生态位宽度,存在不同程度的生态位重叠,对空间和营养资源的利用有不同比例的相似性。依据其各自生物学特性和生活习性的不同达到竞争的平衡和共存。 相似文献
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川硬皮肿腿蜂与中华甲虫蒲螨协同防治天牛类蛀干害虫技术研究 总被引：1，自引：0，他引：1
根据川硬皮肿腿蜂(Scleroderma scichuanensis Xiao)和中华甲虫蒲螨(Pyemotes zhonghuajia)的作用特点和优势,主要以协同防治天牛类蛀干害虫为例,进行野外释放及防效研究。结果表明:川硬皮肿腿蜂和中华甲虫蒲螨对天牛均有控制作用,两者的交互作用,平均寄生率为52.8%,虫口减退率为54.62%,防治效果均优于农药;二者作用时期不同,蒲螨对低龄幼虫寄生率高,肿腿蜂对中高龄幼虫寄生率高。在防治时,应根据两者的作用特点和优势,在不同时间(龄期)进行2种天敌的先后释放可达到较高的寄生率和虫口减退率。 相似文献
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马尾松林中的若干次要食叶害虫是马尾松毛虫的寄生或捕食性天敌的转主寄主,从而使马尾松纯林至少有6条比较稳定的食物链和沿着这6条食物链流动的48条能流线。因此,只要合理地实施人工防治,不滥用化学杀虫剂,能够提高马尾松纯林的自然控制能力,有利于控制马尾松毛虫灾害,并达到综合防治多种食叶害虫的良好效果。 相似文献
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Organic farming system of winter wheat was investigated in Solvakia over three years, 1995–1997. The system was carried out
on a small scale (four plots of 50 m2). Neither pesticides nor inorganic fertilisers were applied. Effect of two treatments, ploughing and previous crop, on the
community of pests and natural enemies was surveyed. There were two types of ploughing (shallow and deep) made in autumn before
sowing. As previous crops, silage-maize and alfalfa were used each season. The effect of all factors was analysed by multivariate
method, redundancy analysis (RDA) and Monte Carlo permutation to assess statistical significance. During three years, 37 taxons
of pests and 27 taxons of natural enemies were recorded. The results of RDA showed that the community of insects (pests and
natural enemies) was mainly influenced by temporal variation. The highest abundance of all insects was observed in 1996. The
effect of the two treatments on the community of pests and natural enemies was less obvious. Pests were found to be significantly
more influenced by ploughingthan by previous crop. Most of pests occurred more abundantly on plots with shallow ploughing
and on plots after maize. Abundance of natural enemies were, however, significantly affected by previous crop. Majority of
them were more abundant on plots after maize than after alfalfa. Ploughing had only marginally significant effect on natural
enemies that were more abundant on shallow ploughed plots. Both ploughing and previous crop had only negligible effect on
species diversity of natural enemies. 相似文献
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Monitoring populations of pests and their natural enemies under different management situations and seasonal weather parameters provides extremely useful information for taking preventive measures against pest outbreaks. The abundance, spatial and temporal distributions of herbivorous insects and arthropod natural enemies on Alnus species were monitored at four sites in Kabale district, Uganda between June 1999 and August 2000. Chewing insects, dominated by Coleoptera (75%), constituted the majority of insect herbivores sampled. Dominant and potentially serious pests of Alnus included Apion globulipenne, an unidentified Chrysomelidae (Coleopt. 27), Phymateus viridipes, Coloborrtics corticina and a Cacopsylla species (Homoptera: Psyllidae). Spiders were the predominant natural enemies accounting for 64% of the total natural enemies encountered, followed by parasitic Hymenoptera (30%). There were marked spatial and temporal variations in arthropod abundance. Among sites, mean abundance of total insect herbivores and total natural enemies on A. acuminata over 15 months ranged from 3.8–8.5 and 3.3–4.7 individuals per 1-m branch length respectively. Over the same period, mean number of total insect herbivores and total natural enemies on A. nepalensis that was studied at only one site were 11.9 herbivores and 4.2 natural enemies per 1-m branch length. Populations of most insect orders increased in the wet season although the greatest herbivore abundance was evident in the dry season. Further studies are necessary on the impact and management strategies of the potentially important insect pests and natural enemies on Alnus.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献