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广东省肇庆市国营林场公司下属12个国营林场,总经营面积65.73万亩,共有边界防火线683公里,截止1988年止,已营造木荷防火林带581公里,另营造工区界防火林带113公里,防火线基本实现了木荷防火林带化。所剩下的102公里边界防火线,除部分石山,1990年可以全部种上木荷。国营大坑山林场是营造木荷防火林带的先行场。该场从1964年营造木荷防火林带,至1975年,全场43公里防火线,已全面完成营造任务。最早营造的木荷林带(18年生),折合活立木蓄积8.4立方米/亩。木荷生产郁闭后,不用年年铲草维修防火线,用扫把扫除枯枝落叶即可,节省用工三分之二以上。1985年1986年,林业部两次在该场进行木荷林带防火抗性试验,在林带边缘,火苗高达12米,均无过火现象发生,木荷部分枝叶干枯,来春又复生。有关参与试验的专家教授,一致认为木荷防火林带抗火性能显著,该项目属全国首创,被评为省林业科技进步三等奖。 相似文献
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我们从１９８８年秋季开始对黑龙江省西部地区的一条典型的、正在受到严重冲刷的农田侵蚀沟进行了以生物措施为主的综合治理。采用的主要措施是：在沟头上方营造截流林带、修筑沟头坝，在沟坡两侧营造防蚀林带、削坡插柳、修筑封沟埂，在沟内密插防冲柳带、设置土谷坊和柳编谷坊。经过五年的治理，受到了良好效果。治理后的１９９３年与治理前的１９８８年相比，该侵蚀沟每年向源侵蚀速度由２．５ｍ减少到０．０５ｍ，沟帮崩塌速度由１．５４ｍ减少到０．０３ｍ，每年侵蚀农田数量由１０００ｍ￣２减少到１９．９４ｍ￣２，平均沟深由２．１８ｍ抬高到１．６６ｍ，泥沙进出量由侵蚀２５００ｍ￣３到沟内淤积３５８．３ｍ￣３，五年内共淤积泥沙７２０．５５ｍ￣３。 相似文献
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研究了无断根沟的17 a生一路双行毛白杨农田防护林的细根特征。结果表明,在距林带5.0m范围和100 cm深农田内的单位土体细根特征值为:根重92.20g/m3,根长641.01m/m3,根表面积1.058 8m2/m3,根体积103.7 cm3/m3,根尖数301 481个/m3。农田内的各细根特征值都随距林带的距离的增加而降低,基本上随着土壤深度先增加后降低,较高值出现在距林带1.5m范围内的20~40 cm或40~60 cm土层,在1.5m到3.0m的区间迅速或明显降低,在3.0m或5.0m以外则缓慢降低并且细根特征的最大值上升到10~20 cm土层。由此可见,根系胁地最强的范围应在距林带3m以内。 相似文献
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福建龙溪县管前乡从82年以来,结合发展果树开展营造田头山边防火林带的试验工作。目前已有20公里防火林带,今年计划扩建100公里,至今已挖穴43公里。从82年以来先后7次阻隔森林火灾,保护了5.3万亩林木。87年9月上旬市林委为了推广管前这一经验,组织各县村委书记主任到实地参观,大家认为在田头山边营造果树防火林带是一个良好的生态生物保护圈,是森林防火一个创举。不仅改变了过去山脊防火路(生土带),而且又解决了山脊防火路无法解决的长短效益。这个乡从今年起按县林委的要求在新造林地上,山脊营造木荷或 相似文献
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采用目测判断、直接火烧、实验测定、火场植被调查和实地营造试验的方法,探究了防火树种的选择和防火林带营造技术。结果表明:防火树种的条件主要是枝叶茂密、含水量大、含油脂少、不易燃烧、耐火性强;下层林木应耐潮湿,与上层林木种间关系相适应;生长迅速、郁闭快、适应性强、萌芽力高;无病虫害寄生和传播。防火能力较强的树种有刺槐、核桃和青杨等;防火能力较弱的树种有三裂绣线菊、华北落叶松和丁香等。防火林带的营造技术条件是造林面积在100hm2以上,防火林带一般设置在山脊、林地边缘等,主林带宽度一般为30m左右,副林带宽度为20m左右,密度越大,防火效果越好。林带营造技术措施主要有整地、栽植和抚育管护。 相似文献
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布海乡位于我省中部平原,属于一般风害区。该乡自1973年以来,共营造农田防护林带243条,全长750华里,构成231个方田网眼,总面积4629亩,保护着十几万亩良田。为了探讨林带的胁地问题,我们于1983年,对该乡八条林带的胁地情况进行了调查。其方法是:在同一个网眼内,于主带的东西方向和付带的南北方向,分别测量各种胁地距离,并选择农作物相同的标准地块进行生长情况调查。共调查九个网眼,测设标准地37块(包括 相似文献
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<正> 营造农田防护林体系是提高农作物产量与质量的有效手段之一。国内外已有不少关于林带使作物增产的报道;法国人Guyot指出,灌溉条件下,林带可使小麦增产21.8％,丹麦人研究认为,可以平均增产5％,据我们1985年研究认为,在100亩左右的长方形林网内平均增产5.5％。有关林网保护下的农作物质量及其增产机制的报导还不多见。为了系统的了解防护林体系保护下的农作物产 相似文献
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《Scandinavian Journal of Forest Research》2012,27(4):369-376
Remote sensing techniques have proven successful for producing stem maps of forests in leaf-on condition from high-resolution imagery. This paper demonstrates how a mathematical model for the surface of a stem can be used to estimate the breast-height diameter of individual trees from aerial photographs to give information on basal area. The diameters are estimated by likelihood estimation from images of a forest in leaf-off condition where the stems and their shadows are visible. Applied to a homogeneous and monospecific oak ( Quercus robur L.) stand under standard silvicultural treatment in Denmark, the estimation was successful for 56 out of 60 trees. The root mean squared error on the diameter was 4.2 and 3.2 cm using three and five images, respectively. The key conclusion is that it is feasible to infer fairly accurate information about the diameters and three-dimensional positions of stems from aerial photographs. 相似文献
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京郊农田防护林景观生态评价--以北京大兴县北藏乡为例 总被引：1，自引：0，他引：1
Based on theories of protective forests and landscape ecology, the reasonableness of structures and patterns of shelterbelt system at Beizang Town, Daxing County, Beijing were analyzed and assessed from the two scales of forest belts and networks, by integrating uses of field investigation, GIS and RS techniques. Results showed that the existent main belt (3-12 m in width) was too narrow, while the assistant belt (3-27.1 m in width) was too wide; the species composition of the existent shelterbelts was single, and the structures and patterns of the shelterbelt system were unreasonable. It is suggested that the structure of the main and the assistant belts should be changed, such as increasing the width of main belts, decreasing the width of assistant belt, and planting more mixed species, and the pattern with arbores in the middle and shrubs in the sides of belts could be taken into account. For the landscape structure of forest network after regenerating or reconstruction, the grid number of closed network should be 13 per km2 and the minimum number of belts should be 34 per km2, This study also testified that integrating GIS and remote technique with landscape ecology could provide an effective method for reasonable reconstruction of the structures and patterns of shelterbelts system. 相似文献
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从“９８洪灾”中看出５０ａ来,长江的治理在策略上是有失误的。首先是长江治理战略思想上的失误,缺乏治理长江流域整体生态环境的系统思想。其次是具体措施上的失误,见水不见山,重水轻山;见水库不见湖泊,重修水库,轻保湖泊、库容;见堤坝不见河道,重筑堤堵水,轻疏导排障;投资重水利,轻林业。治江策略,首先要具有全流域生态环境治理的整体系统思想。对策略措施是“留”、“蓄”、“导” 相似文献
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Nishtman Hatami Peter Lohmander Mohammad Hadi Moayeri Soleiman Mohammadi Limaei 《林业研究》2020,31(1):99-106
The aim of this study was to develop and test a new basal area growth model in mixed species continuous cover forests in northern Iran.Weanalyzed 421 core samples from 6 main species in the forest area to develop our growth model.In each plot,we measured variables such as total tree height(m),diameter at breast height(DBH)(cm)and basal area of larger trees as cumulative basal areas of trees(GCUM)ofDBH[5 cm.The empirical data were analyzed using regression analysis.There was a statistically significant nonlinear function between the annual basal area increment,as the dependent variable,and the basal area of the individual trees and competition as explanatory variables.Reference area from the largest trees,was circular plot with area of 0.1 ha.GCUM was estimated for trees of DBH>5 cm.Furthermore,we investigated the dependencies of diameter growth of different species on stand density at different levels of competition,and diameter development of individual trees through time.The results indicate that competition caused by larger neighborhood trees has a negative effect on growth.In addition,the maximum diameter increment is affected by competition level.Therefore,the maximum diameter increment of species occurs when the trees are about 35–40 cm in dense-forest(40 to 0 m^2 per ha)and when the trees are about 60 to 70 cm in very dense forest(60 to 0 m^2 per ha)which is more likely to Caspian natural forests with high level density due to uneven-aged composition of stands. 相似文献
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Kewu Cheng Runguo Zang Xiaofang Zhou Weiyin Zhang Zhiqiang Bai 《Frontiers of Forestry in China》2007,2(1):66-71
The riparian forests along the Ergis River, west China, composed mainly of Salicaceae species, play an important role in eco-environment
protection and sustainable development of local agriculture, stockbreeding, and social economy of the northern desert region
of Xinjiang Uygur Autonomous Region. The study of the influence of floods on the natural riparian forests is imperative for
the understanding of the successional process and the acceleration of conservation and restoration of forests. By investigating
the relationship between floods and dispersal of seeds, sprouting, natural regeneration, the structure of the forests, and
their current distribution, we conclude that: 1) the ripening and dispersal periods of Salicaceae species seeds overlap largely
with flood occurrence periods, and the sprouting and natural regeneration of seeds depend greatly on flood events; 2) floods
supply soil water and increase groundwater level of riparian land through flood irrigation and horizontal infiltration to
maintain the normal growth of the riparian forests; 3) floods have a decisive influence on the structure, composition, and
distribution pattern of riparian forests, and any disturbance in the water flow has a profound effect on these characteristics.
Given these facts, some management measures for conservation and restoration of the riparian forests are proposed, including
the establishment of riparian forest buffer belt, bank stabilization measures, and maintenance of flood protection.
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Translated from Journal of Beijing Forestry University, 2006, 28(2): 46–51 [译自: 北京林业大学学报] 相似文献
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Sedimentation in Mangrove Forests 总被引：1，自引：0，他引：1
The tidal currents in mangrove forests are impeded by the friction caused by the high vegetation density. The tidal currents are also complex comprising eddies, jets and stagnation zones. The sediment particles carried in suspension into the forest during tidal inundation are cohesive, mainly clay and fine silt, and form large flocs. These flocs remain in suspension as a result of the turbulence created by the flow around the vegetation. The intensity of sedimentation is largest for trees forming a complex matrix of roots such as Rhizophora sp. and smallest for single trees such as Ceriops sp. The flocs settle in the forest around slack high tide. At ebb tides the water currents are too small to re-entrain this sediment. Hence the inundation of coastal mangrove forests at tidal frequency works as a pump preferentially transporting fine, cohesive sediment from coastal waters to the mangroves. Mangroves are thus not just opportunistic trees colonising mud banks but actively contribute to the creation of mud banks. 相似文献
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生态景观林带建设的主要生态学理论与应用 总被引：1，自引：1，他引：0
文章论述生态景观林带建设的主要生态学理论及其应用。在广东省生态景观林带建设中应该以群落生态演替的观点进行生态景观带（面）的建设,应用基于演替原理得出的生态恢复参照系来指导;按群落学的观点进行景观节点（点）建设,依据群落学和生物多样性原理,建立多乔木、灌木、草本、藤本等植物组成的景观节点群落,以作为景观线带物种的补偿地;以生态关学与生物多样性的观点进行绿化景观林带（线）的建设,利用群落的时间格局进行绿化景观林带生态关学的构建,利用群落的空间格局进行绿化景观林带的生物多样性构建;可应用边缘效应原理和种间相互作用原理来构建与管理生态景观林带。 相似文献