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1.
2005—2007年西南地区卫星监测热点分析 总被引：2，自引：0，他引：2
西南是我国受森林火灾危害严重的主要区域,分析我国西南地区森林火灾发生规律对改进这一地区的林火管理有重要现实意义.根据国家林业局林火监测中心提供的2005-2007年卫星监测到的热点数据及相关信息,发现2005-2007年西南地区热点主要分布在云南、广西和贵州西南部,所有监测到的热点中30.1%是农业用火,主要分布在云南西南和南部;44.6%的热点可能是野外植被燃烧引起的,这些热点包括草原、灌丛、森林和荒地上的火烧以及计划烧除、炼山等.西南地区的火烧主要发生在11月-翌年5月,1-5月份发生的火烧占全部野火热点的77.6%.森林火灾集中分布在云南东部和西北部、贵州东南部和广西大部分地区.由于这一地区人为火源和农业用火较多,加强研究区内高火险天气的火源管理是减少森林火灾的重要有效措施. 相似文献
2.
大兴安岭南部春季火行为特征及可燃物消耗 总被引：3，自引：1，他引：2
利用标准地调查分析2007年春季大兴安岭2起森林火灾的火行为及可燃物变化.采用加拿大火险天气指数(FWI)系统分析火险变化,地表可燃物载量调查采用线状相交可燃物调查方法,并利用MODIS遥感数据对火烧程度进行分级.结果表明:FWI系统各指标可以很好地指示森林火险变化,2007年4-5月细小可燃物湿度码(FFMC)基本都在90以上,腐殖质湿度码(DMC)和干旱指数(DC)在4月份持续升高,2场大火也发生在火险高的时段.火烧类型以地表火为主,部分林分有冲冠火.火后阔叶林地表径级可燃物增加不明显,针阔混交林主要是5.0～6.99 cm径级可燃物增加,而落叶松纯林火烧后除0.50～0.99 cm径级可燃物减少外,其他径级可燃物都明显增加.不同火烧程度对地表可燃物载量的影响有差异.中度和重度火烧后草本盖度明显下降,有些林分下木层死亡率较高.罕诺河火场和松岭区壮志林场过火区重度火烧分别占33.2%和46.4%. 相似文献
3.
大兴安岭地区森林火险变化及FWI适用性评估 总被引：3，自引：0，他引：3
根据研究区内及附件气象站每日气温、相对湿度、24小时降水和风速计算1987—2006年大兴安岭每日的加拿大林火天气指数系统(FWI)各组分值。利用空间插值方法,获得1987—2006年所有森林火灾发生日的FWI系统各组分值。大兴安岭林区森林火灾主要发生在落叶针叶林(61.3%)、草地(23.9%)和落叶阔叶林(8.0%),主要火源是雷击火(占57.1%)。4—6月份森林火灾发生时的FWI、FFMC和ISI平均值高。根据1987—2006年FWI组分指数的分布和火发生情况,对森林火险指数进行了分级,低、中、高、很高和极高火险的FWI取值范围分别为0～2.5,2.6～10.0,10.1～18.0,18.1～31.0,≥31.1。FWI对大兴安岭地区森林火险有显著的指示意义,FFMC和ISI对预测火灾的发生与蔓延有较好的指示作用。1987—2001年每年明显有春季和秋季2个火险期,但2002—2006年火险期显著延长。春季火险严重度指数(SSR)波动幅度比较大,夏季SSR和春季SSR有相反的波动趋势,2000—2006年秋季火险严重度明显升高。 相似文献
4.
雷击火是中国大兴安岭地区重要火源.根据1990-2006年研究区内10个气象站日观测数据包括最高气温、最小湿度、24 h降水、平均风速等指标计算每日FWI系统各指标,分析雷击火的发生与火险指数的关系.根据各气象站与研究区质心的距离确定各气象站的权重,计算研究区火险指数平均值.1990-2006年大兴安岭林区共发生森林火灾591起,其中雷击火359起,占60.7%.70%的雷击火分布在121°～125°E,51°～53°N,平均每起雷击火过火面积为797.37hm2,森林受害面积为581.67 hm2.71.9%、2.5%和17.3%的雷击火分别发生在落叶针叶林、落叶阔叶林和草地.雷击火发生在4-9月,5-8月是雷击火多发月份.1990-2006年雷击火发生时间段整体上有延长趋势.8月和9月发生的雷击火都发生在1998-2005年.雷击火的发生受气温与降水的影响,月均气温高、降水量少,雷击火次数明显多.发生雷击火日的平均可燃物湿度码FFMC、DMC、DC和FWI分别为90.3,69,6,287.4和24.7.雷击火发生日各火险成分指数平均值均高于1990-2006年4-9月总体平均值.根据雷击火发生概率和每日火险指数建立了雷击火发生概率预测模型. 相似文献
5.
未来情景下西南地区森林火险变化 总被引：1，自引：0，他引：1
采用区域气候模式输出的日值和加拿大森林火险天气指数系统,在50 km×50 km尺度下,分析IPCCSRES A2和B2情景下中国西南地区未来不同时段区域森林火险和森林火险期变化,为科学制定未来林火管理规划提供参考.气候情景数据使用区域气候模式系统(PRECIS)对中国区域1961-2100年SRES A2,B2情景下的气候模拟结果,计算研究区各格点森林火险天气指数( FWI),并利用ANUSPLIN软件把研究结果插值到1 km×1 km水平.结果表明:PRECIS模式对研究区的平均气温和月均降水均有较好的模拟能力,气温和降水空间分布形态及中心区域与观测数值基本一致.A2和B2情景下西南地区火险期(11月至翌年5月)内森林火险天气指数平均分别增加1.66和1.40.A2和B2情景下2041-2050年火险期FWI平均变率分别为1.22倍和1.24倍,表明A2和B2情景下西南地区的森林火烧面积在2041-2050年可能比基准时段增加22％和24％,并且在火险高的月份潜在的森林火烧面积增加更为明显.与基准时段相比,2种情景下都表现出低火险日数明显减少和极高火险日数显著增加的趋势.A2和B2情景下,2041-2050年高、很高和极高火险等级总日数分别增加17和13天.建议根据未来森林火险和火险期变化特点,加强早期预警、火灾监测和可燃物管理等,提高该区域适应气候变化的能力. 相似文献
6.
以林分为空间单元,动态评估小班尺度潜在森林火灾风险对于火灾预防管理实践具有重要作用。研究以云南临沧市临翔区多年采脂思茅松林分为对象,采集多年未采脂、采脂条件下的林分因子样本,以火源可及性、死可燃物载量、林分易燃性,以及坡度、坡向、地表湿润度为评估变量,构建小班尺度上的森林火险评估模型,分别评估林分在全国火险等级模型下的基础火险值(BHX)、未采脂条件下的静态火险值(SHX)及采脂条件下动态火险值(DHX)。在地理信息系统(GIS)支持下,利用地图模拟表达采脂活动引起林分可燃物载量和易燃性、火源密度等增加下的火险动态变化格局,并分析林分森林火险等级大幅变化原因。研究结果表明:研究区所有林分具有一致的基础森林火险值(BHX),危险性大;林分可燃物条件差异造成的未采脂林分静态火险值差异较大,大部分小班处于高火险等级;林分因采脂经营活动使各小班火险值呈现不同程度的增加,林分火险等级主要集中在极高火险,火险上升比率大于25%的林分面积超过60%;过度、非规范的采脂经营活动是林分火险等级增加的主要原因。林分是森林经营活动的基本单位,火险评估精细化至不同经营水平下的林分小班尺度,研究对基层林火管理及其它经营措施下火险动态评估具有一定的参考及借鉴价值。 相似文献
7.
本文根据河北省森林火灾的材料,对森林火灾的规律与特点进行了初步探讨。结果表明,河北省森林火险期长,高火险期集中,火警频繁,森林火灾的火因均为人为火源。因此,在森林防火工作中,采取多种措施,强化火源管理,辅以必要的森林防火设施设备,提高森林火灾的综合控制能力,就可以将森林火灾的损失控制在最低限度以内。 相似文献
8.
不管森林火险等级多高,危险多大,没有火源,森林火灾是不会自行发生的。火源来自四面八方,十分复杂,无时无刻都有发生森林火灾的可能,以福建省天气情况为例:高温、干燥、少雨天气出现在每年的6、7、8、9月,给森林火灾的出现提供了易燃条件,照理火灾的次数一定很多,而实际情况又不是这样,主要原因是我省农、林业生产用火不在这时候,火源出现频率低。据福建省1987年全省森林火灾情况统计,1至3月占全年82.6%;10至12月占6.6%;4至9月占10.8%,由此清楚地看出1至3月发生的森林火灾次数占全年绝大部份。这主要是福建省农村春耕前的备耕工作在这段时间,用火较多,产生的火源也较频繁。有了火源,发生火灾的 相似文献
9.
10.
对杭州市2000-2008年的森林火灾发生特点进行了分析,结果表明,森林火灾各年间发生的次数呈波浪状变化与不同年份大气环流气候变化相关;森林火灾主要发生在春冬两季,这与杭州市冬季晴冷少雨、空气干燥的气候特点以及炼山等人为用火活动规律相关;森林火灾次数日发生相对集中在10：00-16：00,占火灾总次数的83%;森林火灾的发生与森林植被类型相关,在针叶林的发生次数、受害面积最多;森林火灾发生火源99%是人为火源;森林火灾在中、幼林发生的次数较多,占总次数的80%。指出杭州市存在气候条件不利,林中可燃物多,森林消防基础设施条件差,森林防火长效管理机制不完善,防火意识弱,防火责任不够实,防火队伍质量不高,森林自身防火性能不高等问题。提出了完善森林防火长效机制：完善责任追究机制、考核机制、群防群治机制、火源管理机制、森林防火投入机制及各种森林防火的规章制度;严重干旱期间及高森林火险等级天气期间采取超常规措施,在各县（市）区适时颁布“禁火令”,规定禁火期间和禁火区,禁止一切野外用火;营造生物防火林带,改造针叶林成阔叶提高森林自身的防火性能等措施。 相似文献
11.
《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
12.
《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
13.
《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
14.
《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
15.
本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献
16.
《Scandinavian Journal of Forest Research》2012,27(2):131-138
The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided. 相似文献
17.
18.
《Scandinavian Journal of Forest Research》2012,27(5):472-479
Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken. 相似文献
19.
Srisuda Thippayarugs Banyong Toomsan Patma Vityakon Viriya Limpinuntana Aran Patanothai Georg Cadisch 《Agroforestry Systems》2008,72(2):137-148
In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic
or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts
(stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea
(Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content
as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest
N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized
to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea,
largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for
N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant
components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N
released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures
were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality
components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in
the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols.
Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest
age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its
components are mixed. 相似文献
20.
A. Rigueiro-Rodríguez M. R. Mosquera-Losada E. Gatica-Trabanini 《Agroforestry Systems》2000,48(3):245-256
The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste
disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization,
(2) milk sewage sludge at 40 kg N ha−1 target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two
pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha−1. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1); (2) Lolium perenne L. var. Tove (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea
(Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m2, with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect
on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage
sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but
affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral
systems.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献