大兴安岭呼中森林大火碳释放估算

森林火灾不仅破坏森林生态系统,还向大气中释放了大量含碳温室气体,影响碳循环。对林火碳释放进行有效地估算,可以更加深入了解林火对碳循环的作用。利用卫星遥感影像,分析了2010年6月大兴安岭呼中森林大火后植被指数变化,对火烧程度进行了分级,结合野外火烧迹地调查和可燃物含碳率,估算出不同火烧等级、不同植被类型林火过火面积、火烧消耗可燃物量和释放碳量。结果表明:此次大兴安岭呼中森林大火总过火面积为5 812.4hm2,消耗可燃物总量76 742.51t,释放碳34 534.13t,其中落叶松林和针阔混交林释放碳量分别为14 934.16和19 599.97t。     

林火碳排放模型研究进展

林火作为干扰因子, 影响着森林演替、森林生物量和生产力以及生物地球化学循环。森林燃烧所释放的含碳温室气体对全球气候变化具有重要影响。对森林火灾释放的含碳气体进行有效估算, 可以弄清林火产生的含碳气体对全球碳循环的影响。文中介绍了2种林火碳排放模型, 即基于有效可燃物模型和火干扰下碳循环模型。通过对这2种估算方法的比较, 指出未来林火碳排放估算方法的发展趋势。     

卫星遥感技术在林火管理与研究中的应用(英文)

卫星遥感已经成为森林火险等级预测、可燃物和火烧区制图、林火监测和火生态研究的一个主要数据来源。本文综述了这些研究领域的研究成果,分析了未来林火管理中采用的卫星遥感技术的发展趋势。根据卫星遥感数据制取的可燃物分布图可以满足林火管理在空间和时间尺度上的需要。单独采用遥感数据或结合地面气象数据可以生成一些火险指数,用于森林火险的预报。目前NOAA 和MODIS 卫星由于有高的时间分辨率已被广泛用于林火探测和监测,这些监测结果可以在许多林火网站上见到,这为世界各地的林火管理和研究提供了重要的参考资料。作为低成本的有效工具, 卫星遥感技术在确定火烧面积和过火区制图上发挥了重要作用。遥感技术的发展也可以用来推断火烧时间和估计火烧程度。卫星遥感也非常适合用来估计生物燃烧面积,这是估计全球或区域生物燃烧排放量和理解火对全球变化的影响的基础。本文还讨论了林火研究中采用的卫星类型。文章最后建议中国需要在卫星遥感技术的应用上进一步发展,提高我国的林火管理水平。参71。     

大兴安岭呼中区2010年森林火灾碳排放的计量估算

林火是森林生态系统中特殊而重要的生态因子,亦是导致植被和土壤碳储量动态变化的重要干扰因子.森林火灾的碳排放对气候变化及大气碳循环具有重要影响,科学有效地对其进行计量,对了解区域和全球的森林生态系统碳循环和碳平衡具有重要意义.根据大兴安岭野外森林可燃物的调查数据和2010年森林火灾统计资料,利用GIS技术工具,通过野外火烧迹地调查与室内控制环境实验相结合的方法确定各种计量参数,从林分水平上,采用排放因子法,估算大兴安岭2010年森林火灾碳排放量和含碳气体排放量.结果表明:大兴安岭2010年森林火灾碳排放量为117 870.62t;含碳气体排放量CO2、CO、CH4和NMHC分别为379 606.01,23 425.74,1 081.46和758.61 t.虽然针阔混交林火烧面积占总过火面积的26.35％,但是碳排放量只占总排放量的13.79％,而2种偃松林型的火烧面积只占总过火面积的29.92％,碳排放量却占总排放量的50.35％,对此提出了相应的林火管理策略.研究结果为正确认识森林火灾对区域碳平衡及全球生态环境的影响提供参考数据.     

林火与气候变化研究进展

火是全球大多森林生态系统中的一个重要干扰因子, 它对大气中的温室气体和气溶胶的增加有显著影响。林火与气候变化是当前林火研究领域的热点问题。文中综述了气候变化对林火的影响和林火排放物对气候变化的影响。大量研究表明, 气候变化将导致森林火险期延长, 出现潜在极端火行为的天数增多, 森林火灾更加严重, 特别是北方森林火灾增加显著。未来的研究趋势是, 采用卫星遥感数据在大尺度上研究气候变化对林火的影响, 把林火模型与气候模式和全球植被动力学模型耦合, 构建更为复杂的林火排放模型, 以深入揭示林火与气候变化的关系。     

大兴安岭6种主要乔木树种燃烧过程的含碳气体释放特征

【目的】气候变暖带来的环境问题越来越突出,含碳气体排放量增加是温室效应的主要原因,而森林火灾排放含碳气体仅次于化石燃料燃烧,是全球变暖的重要因素,为了实现定量探究森林火灾对气候变暖的影响,需要准确估算森林火灾含碳气体的排放量。【方法】以大兴安岭6种主要乔木的枝和叶为研究对象,通过室内燃烧试验的方法,利用Testo350烟气分析仪测定其在燃烧过程中含碳气体的排放量,分析不同可燃物排放气体差异性,并计算可燃物的排放因子和修正燃烧效率。【结果】1)燃烧过程中6种乔木枝、叶燃烧含碳气体(CO、CO_2、CxHy)排放量的平均值枝为2 406.18、18 486、184.88 mg·dm~(-3);叶为2 297.43、20 548.6、166.27 mg·dm~(-3);2)6种乔木枝的CO_2气体排放量差异不显著,樟子松叶的CO_2排放量显著低于其余5种乔木,剩余5种乔木差异不显著。6种乔木枝和叶的CO、C_xH_y排放量差异显著;3)6种乔木枝、叶含碳气体的排放因子(EFi)范围分别为CO(118.97～195.00)、CO_2(1 290.12～1 672.50)、C_xH_y(8.10～17.32)g·kg~(-1);4)叶的修正燃烧效率(MCE):针叶乔木阔叶乔木;同种针叶乔木的修正燃烧效率(MCE):枝叶,而同种阔叶乔木的修正燃烧效率(MCE):枝叶。【结论】根据气体排放量计算了不同气体的排放因子,利用排放因子可对大兴安岭森林火灾排放的含炭气体进行估算;修正燃烧效率结果能定量反映出本文在实验条件下可燃物都达到了明然状态,修正燃烧效率越低产生的不完全燃烧产物就越多;修正燃烧效率结果说明了针叶乔木叶相对于阔叶乔木叶燃烧不充分,针叶乔木叶燃烧产生的CO量多;研究结果将对估计大兴安岭森林火灾含碳气体排放总量和其对环境的影响提供一定的理论依据。     

森林地表死可燃物含水率预测模型研究进展

林火是影响森林生态系统的重要因子之一,林火蔓延和发展深受森林可燃物含水率的影响,尤其是林火的发生直接受地表死可燃物含水率的影响。因此,准确预测森林地表死可燃物含水率是预报森林火险和火行为的关键,加强森林死可燃物含水率预测模型研究尤为重要。从森林可燃物含水率的研究方法、研究模型及模型精度3方面综述研究现状,并对比评价现有模型。针对目前研究的诸多问题,提出5点展望:1)加强研究重点火险区野外含水率动态。利用已有的森林火险因子采集站和森林火险监测站获取不同环境因子和可燃物含水率及气象因子监测数据,构建重点火险区基于气象参数的森林可燃物含水率预测模型。2)加强森林可燃物的基础数据监测和收集。这可为全面构建森林火险等级系统奠定坚实的数据基础,同时还应建立精准的森林可燃物类型划分体系。3)加强研究可燃物含水率的空间异质性。应考虑不同影响因子下可燃物含水率动态,特别是了解小尺度内森林可燃物含水率的空间异质性,才能更准确进行林火预测预报。4)结合应用增强回归树(BRT)方法来提高模型精度。在可燃物含水率模型精度影响因子的研究中,运用BRT方法多次随机抽取一定量的数据,量化分析不同因子对模型精度的影响程度。5)结合GIS进行大尺度火险预警研究。综合应用RS和GIS技术,建立可燃物含水率的遥感反演模型,在准确模拟森林可燃物含水率空间分布的基础上,建立基于可燃物含水率的不同火险等级的预测模型。     

北方森林林火发生驱动因子及其变化趋势研究进展

北方森林作为气候变化最敏感的陆地生态系统之一,近些年来随着林区气候变暖,林火发生的数量和过火面积都呈显著的增加趋势,因此研究北方森林林火发生驱动因子及其变化趋势对维护其生态系统的稳定具有重要意义。文中主要从北方森林林火发生的主要控制因子和未来气候变暖条件下林火发生的预测方法及变化趋势进行综述。研究结果表明,林火的驱动因子既包括在大尺度上气候的作用,也包含植被、地形、可燃物和人类活动等局部尺度的影响。近几年来对气候变暖下林火状况趋势预测更倾向综合考虑气候和局部控制因子的作用。对我国而言,需要在更大的区域尺度上开展林火发生预测的研究。研究认为,北方森林林火变化趋势及预测研究的关键问题在于如何在不同空间尺度上确立林火发生的关键控制因子以及完善现有的林火预测方法。     

大数据技术在林火预测预报中的应用初探

林火预测预报是综合气象要素、地形、可燃物的干湿程度、可燃物类型特点和火源等,对森林燃烧的危险性进行分析预测。林火因子众多,气象要素时刻在变化,可燃物类型多种多样,林火预报数据庞大,准确地进行林火预测预报面临诸多困难。利用大数据的高速、大量、准确、多样等优势能解决林火预测预报中面临的问题。对大数据技术在制作林火预测预报系统、分析火灾规律、筛选林火预报主导因子、处理林火因子等方面进行了设想,并对大数据方法在林火预测预报中的应用进行了展望。     

小兴安岭主要森林可燃物类型地被物燃烧烟气分析

通过烟气分析系统测定小兴安岭地区15种森林可燃物类型地被物未分解层和半分解层燃烧过程中CO2,CO,CxHy,NO和SO2的排放因子和释放量,并分析不同可燃物类型的排放差异性和5种气体的相关性.结果表明:15种可燃物类型地被物燃烧5种气体的排放因子分别为3.16,0.31,0.007 0,0.005 4和0.019;5种气体总量、含碳气体总量和C02的释放总量分别为:1 330.56,1 321.25和1 200.56 mg·g-1,且均为半分解层大于未分解层;而CO,CxHy,NO和SO2的释放总量分别为:118.02,2.66,2.06和8.21mg·g-1,半分解层均小于未分解层;CO2,CO,CxHy和SO2的释放量之间存在着极显著的相关性(P＜0.01),而NO与这4种气体之间无显著相关(P＞0.05).研究结果将为评价森林火灾对大气环境造成的影响以及森林地被物的管理提供一定的科学依据.     

Chapter 12. A Wildfire and Emissions Policy Model for the Boise National Forest

Summary

We utilized the Boise National Forest's Hazard/Risk model, along with fire history records and fire behavior models, to estimate the current and anticipated levels of large wildfires and associated greenhouse gas and particulate emissions based on the forest condition and wildfire regime on the BNF. The model indicated that the forests at greatest risk of large, intense wildfires are the dense pondero-sa pine-Douglas-fir forests that make up over 1.1 million acres on the forest. We conclude that without an aggressive treatment program to reduce large areas of contiguous heavy fuel loadings the forest will be burned at an annual average rate of about 7.5% of the remaining at-risk forest. Using recent fire data to develop average patterns of intensity in wildfires within this forest type, we estimate that emissions will average around 1 million tons of carbon (C) per year over the next 20 years as the bulk of the ponderosa pine forests are burned. An aggressive treatment program featuring the removal of fuels where necessary, and prescribed fire as a means of re-introducing fire to these ecosystems, would result in a 30-50 percent reduction in the average annual wildfire experienced in the dense ponderosa pine forests, a 14-35% decrease in the average annual C emissions, and a 10-31% decrease in particulate emissions. We argue that the most effective way to curb emissions is with an aggressive treatment program linked to a landscape-based ecosystem management plan. This would have the effect of breaking up large contiguous landscape patterns so that fires become more patchy and diverse in their environmental impact, resulting in significantly reduced emissions as well as improved landscape diversity.     

火干扰对森林碳库影响的量化研究进展

火干扰是森林生态系统的主要干扰因子之一, 会对森林碳储量和碳动态产生重要影响。准确量化火干扰对森林中各碳库的影响程度, 对国家及全球碳预算具有重要意义。文中对国内外火干扰下森林碳储量的研究现状、研究方法和研究内容进行了综述。大量研究表明, 燃烧效率、火烧烈度等关键因子的准确量化是精确估算火干扰对森林碳储量影响的基础, 火烧样地调查与遥感反演法和模型模拟法的综合运用有利于精确量化火干扰下的森林碳库, 各种火烧数据源的同化处理是准确揭示火干扰对森林碳库影响的重要保证。在此基础上, 提出一些更加准确量化火干扰对森林碳储量影响的研究途径, 并对未来的研究方向进行了展望。     

LOSS ASSESSMENT OF BURNED FOREST USING REMOTE SENSING AND GEOGRAPHICAL INFORMATION TECHNIQUES

After forest fire,It is very needd to locate fire position and assess the loss of forestresources.In this paper,a method of burned forest assessment with satellite remote sensing dataand over-laying techniques is discussed and used in the assessment of the burned forest in Malinforest Farm after the large forest fire of May,1987.     

基于Landsat 8遥感数据的森林火灾过火面积估算

以贵州省毕节市赫章县2021年3月18日较大森林火灾为例,利用火灾前后Landsat 8遥感数据及ENVI遥感数据处理分析软件,通过图像预处理、计算归一化植被指数和燃烧面积指数等方法,提取森林火灾过火区域,计算过火面积。结果表明,利用Landsat 8数据能够较好地提取森林火灾过火区域,过火面积估算准确率达96.2%。     

Understorey fuel load estimation along two post-fire chronosequences of Pinus halepensis Mill. forests in Central Greece

Pinus halepensis forests are among the forest ecosystems in the Mediterranean Basin most affected by fire. Their distribution across lowland areas, in particular along the wildland–urban interface, increases the need to understand their ecology and responses to fire regime for their effective management. Apart from the extremely flammable tree layer, in several stands of these forests there is an increased fuel load attributed to the well-developed understorey of evergreen sclerophyllous shrubs. Taking into consideration that, in contrast with the long period required for full development of post-fire-regenerating pines, these shrubs resprout vigorously within the first post-fire weeks, it is important to explore the temporal trend of fuel accumulation to determine the risk of a second fire across a burned landscape. Two post-fire chronosequences of, in total, 12 P. halepensis stands were considered for sampling in Central Greece. The first chronosequence corresponds to pine stands characterized by the dominance of evergreen sclerophyllous shrubs in the understorey (Type 1) whereas the second chronosequence corresponds to pine stands where the cover of such shrubs was lower (Type 2). This study helps in understanding the fuel dynamics according to the type of P. halepensis forest stand and to anticipate future biomass growth. The proposed equations are simple tools, enabling land managers to estimate understorey total fuel load easily by visually recording the cover and height of the evergreen sclerophyllous shrub component, to justify understorey fuel reduction measures.     

Analyzing the effectiveness of alternative fuel reductions of a forested landscape in Northeastern China

Successful management of forest fire risk in the Northeastern China boreal forest ecosystem often involves trade-offs between fire dynamics, fire hazard reduction, and fiscal input. We used the LANDIS model to study the effects of alternative fuel reduction strategies on fire dynamics and analyzed cost effectiveness for each fuel reduction strategy based on cost–benefit theory. Five levels of fuel treatment area (2, 4, 6, 8, and 10% for each decade) and two fuel treatment types (prescribed burning [PB] and mechanical treatments in combination with prescribed fire [PR]) under current fire suppression simulated by LANDIS were compared in a 5 × 2 factorial design over a 300-year period. The results showed that PR scenarios are more effective at reducing the occurrence and burn area of catastrophic fires than PB scenarios. In addition, area burned by high intensity fire can be tremendously reduced by increasing low intensity fires with a higher level of treatment area under the various PR scenarios. The cost effectiveness of alternative fuel reduction strategies is strongly dependent on treatment area. In general, PB scenarios will be more cost effective in larger treatment areas and PR scenarios in smaller. We recommend mechanical treatments in combination with prescribed fire, with 4% of landscape treated in each decade (PR04) to be the optimal fuel reduction strategy in the study area based on risk control and cost efficiency analysis. However, the most challenging work in China is to make local forest policy makers and land managers accept the ecological function of fire on forest ecosystems.     

Prehistoric fire area and emissions from California's forests,woodlands, shrublands,and grasslands

In the majority of US political settings wildland fire is still discussed as a negative force. Lacking from current wildfire discussions are estimates of the spatial extent of fire and their resultant emissions before the influences of Euro-American settlement and this is the focus of this work. We summarize the literature on fire history (fire rotation and fire return intervals) and past Native American burning practices to estimate past fire occurrence by vegetation type. Once past fire intervals were established they were divided into the area of each corresponding vegetation type to arrive at estimates of area burned annually. Finally, the First Order Fire Effects Model was used to estimate emissions. Approximately 1.8 million ha burned annually in California prehistorically (pre 1800). Our estimate of prehistoric annual area burned in California is 88% of the total annual wildfire area in the entire US during a decade (1994–2004) characterized as “extreme” regarding wildfires. The idea that US wildfire area of approximately two million ha annually is extreme is certainly a 20th or 21st century perspective. Skies were likely smoky much of the summer and fall in California during the prehistoric period. Increasing the spatial extent of fire in California is an important management objective. The best methods to significantly increase the area burned is to increase the use of wildland fire use (WFU) and appropriate management response (AMR) suppression fire in remote areas. Political support for increased use of WFU and AMR needs to occur at local, state, and federal levels because increasing the spatial scale of fire will increase smoke and inevitability, a few WFU or AMR fires will escape their predefined boundaries.     

黑龙江省1980—2005年森林火灾时空特征

森林火灾是林火失去人为控制,在森林内自然蔓延和扩展,对生态系统和人类带来一定危害和损失的森林起火。森林火灾属世界性、跨国性的重大自然灾害,进入20世纪80—90年代以来,全球气候变暖导致森林火灾有上升的趋势,虽然各国的森林防火费用不断增加,但森林火灾发生的面积并未相