Division of forest fuel type areas of Heilongjiang Province by using GIS

Eight factors, including forest coverage, fuel load, species composition, elevation, monthly mean temperature, monthly mean relative humidity, monthly mean wind velocity, and monthly mean precipitation of fire season, were considered and the methods of weight, the cumulative probability, ARC/INFO technique, and raster-to-vector conversion were adopted in division of forest fuel type area. Firstly, the electronic maps of forest distribution and administrative divisions were built, then overlaid and transformed to the real-world coordinates. Finally, the forest fuel type areas of Heilongjiang Province including 81 counties were divided into five grades, accounting for 16%, 17%, 17%, 11%, and 38% respectively. The grade Ⅰ fuel type areas with highest fire danger rating mainly distributed on Daxinganling Mountains, Xiaoxinganling Mountains, and Zhangguangcailing Mountains, the grade Ⅴ fuel type areas mainly centralized on Songnen Plain, Sanjiang Plain, and other Plains, and other forest fuel type areas (grades Ⅱ, Ⅲ, and Ⅳ) were situated between plains and mountainous areas.

Supercritical extracts of forest fuels in Great Xing＇an Mountains

Extracts are important components of fuels. Fatty-extracts with high heating value （HV） are hypothe- sized by researchers as positively related to the HV of fuels. The Soxhlet extractor is typically used to extract fatty-extracts but it has shortcomings, including long processing time （8-10 h） and the requirement for large amounts of organic solvent. Supercritical extraction is an alternate and useful technique for extraction of natural products. However, published studies rarely discuss the relationship between extracts and HV. In this study, we assessed the supercritical extracts （SUE） of forest fuels in the Great Xing＇an Mountains. Our results indicated that the optimum conditions for extraction of SuEs were 40-60 mesh, 40-50 MPa, 45℃, 80 min and a CO2 flow rate of 1.5-2.0 dm3/min. The Soxhlet extracts contents and the SuE contents were all related to HV. However, R2 of the coniferous samples （0.8499） and needle samples （0.9722） demonstrated that the correlation between HV and the SuE content was closer. We conclude that supercritical fatty-extracts provide a useful index of the HV of fuels, especially coniferous fuels. SuE data can be used in fire management, for example to estimate the rate of fire spread or fire intensity.

DYNAMIC PREDICION OF FOREST FUEL LOADS BY GREY VERHULST MODEL

The variation of fuel loads after a fire for three forest types, phododendron -Larix gmetinii forest, herb--Larix gmelinii forest and herb--Betula plalyphlla forest , in the northern forest area of Daxing’anling region was discussed. The dynamic models were developed by gray theory for estimating the fuels loads of arbor- shrub, herbs’ grass, litter, and semi-decomposed litter, inflamma ble fuel and the total fuels in each forest type. After a fire, the inflammabIe fuel loads in phododendron-- Larix gmelinii forest and in the herb- - Betula platyphlla fores was estimated at 10.958 t/hm2and 10.473 t/hm2 respectively’ by 13 years later. and that was 12.297 t/hm 2 in herb--Larix gmeliniiforest by 7 years later.. It was predicated that a big fire may occur after 10 years based on inflammable fuel biomass accumulated.

DYNAMIC MODELS OF MOISTURE CONTENT OF FOREST FUELS

The fuel moisture content is an integral part of any workable fire danger-rating system. This paper presented dynamic models for estimating 1-h, 10-h. 100-h and 1000-h timelag fuels, that were developed by multiple regression and stepwise variable selection of statistics. The variables include both meteorological factors and moisture contents observed prior to the day correspondingly. The analysis revealed that the fuel moisture content are correlated positively with the precipitation of 24 hours prior to the observation time, and negatiyely with air temperature at observing height of 1.5 meter in forest.

Diurnal variation models for fine fuel moisture content in boreal forests in China

Studying diurnal variation in the moisture content of fine forest fuel(FFMC)is key to understanding forest fire prevention.This study established models for predicting the diurnal mean,maximum,and minimum FFMC in a boreal forest in China using the relationship between FFMC and meteorological variables.A spline interpolation function is proposed for describing diurnal variations in FFMC.After 1 day with a 1 h field measurement data testing,the results indicate that the accuracy of the sunny slope model was 100%and 84%when the absolute error was<3%and<10%,respectively,whereas the accuracy of the shady slope model was 72%and 76%when the absolute error was<3%and<10%,respectively.The results show that sunny slope and shady slope models can predict and describe diurnal variations in fine fuel moisture content,and provide a basis for forest fire danger prediction in boreal forest ecosystems in China.

A Geographical-Origin-Destination Model for Calculating the Cost of Multimodal Forest-Fuel Transportation

As a consequence of increasing demand for wood fuels, the management of forest-fuel production chains has become an important logistics issue in FinlandandSweden. Truck-based transportation has been the dominant method in fuel supply from the areas around power plants. However, increasing demand has led to enlargement of supply areas and greater variety in supply methods, including also railway and waterway transportation. This study presents a GIS-based calculation model suitable for cost calculations for power plants’ forest-fuel supply chains. The model has multimodal properties—i.e., it provides transfer of forest-fuel loads between transportation modes—and enables case-specific adjustment of transportation and material-handling cost parameters. The functionality of the model is examined with a case study focusing on a region of intense forest-fuel use. The results indicate that truck transportation is competitive with railway transportation also for long transport distances. However, increasing the proportion of multimodal transportation for other than economic reasons (e.g., for supply security) could be reasonable, since the impact on total supply costs is marginal. In addition to honing of the parameters related to biomass availability and transport costs, the model should be developed through inclusion of other means of transportation, such as roundwood carriers.

Southeast Tibet Forest Fuel Types and Flammability

Southeast Tibet forest is in east subtropical zone. This region natural environment is unique, influenced by the southwest monsoon, so forest fires are very easy to occur in the dry season. Forest in this region is over mature forest, and accounts for much proportion. Fire season in this area is winter and spring. But in the special year, forest fires can also occur in the hot summer. Fire season lasts from October to next February,but to April in an individual arid year. Most of the fires in this area are surface fires, crown fire, can occur after long time drought. Ground fires do not occur in the region.

THE ESTIMATE OF THE EFFECTIVE FUEL COMBUSTION VALUE OF FOREST COMMUNITY IN THE DAXINGAN MOUNTAIN

Under the condition of absolute dry, more than thirty forest fuel pararneters,ash content. extract and burning point were measured. By the method of regression step by step. we found an experience formula which can estimate effective fuel high combusti on value of forest community from the Daxingan Mountain,and then,By means of modifying moisture content. we gave an approximate formula about actual heat releasing of forest fuels in the forest fire behavior.

云南省果林修剪枝条资源评估及生物质能潜力分析

以2010—2020年果林修剪枝条及45个水果种植(柑橘、石榴、苹果、梨和葡萄)主要优势县(市、区)为研究对象,利用果林修剪系数及折标煤系数,测算云南省果林修剪资源量,估算生物质燃料潜力,解析其时空分布特征。结果表明:2010—2020年云南省果林修剪枝条资源总量呈上升趋势,枝条年均修剪用量为152.27万t,不同区域之间果林修剪枝条资源量差异明显;2020年云南省果林修剪枝条资源量为261.75万t,其中超10万t的县(市、区)6个,5万~10万t的县(市、区)份有8个,低于5万t的有31个;将枝条制成颗粒燃料折算成标准煤,年均量为91.80万t,标准煤折算成天然气和发电量,年均量分别为69.03亿m^(3)和74.72亿kW·h,其产生的年均潜在价值为41.84亿元。云南省果林修剪枝条能源化潜力巨大,发展生物质燃料的资源禀赋条件优异,具备产业化发展生物质颗粒燃料的资源基础。

基于Sentinel数据的沅陵县针叶林可燃物载量估测研究

森林可燃物是引发森林火灾的重要因素之一,准确估测森林可燃物载量对于制定火灾防控策略、提高火灾预警能力以及保护生态环境具有重要意义。以湖南省沅陵县Senitnel-1A和Sentinel-2A影像为数据源,通过提取多源数据的不同类型遥感因子,结合地面调查获取的样地可燃物载量信息,采用前向特征筛选法和4种机器学习模型[多元线性回归(multiple linear regression,MLR)、k最近邻(k-nearest neighbor,kNN)、支持向量机回归(support vector regression,SVR)、随机森林(random forest,RF)]构建了针叶林可燃物载量反演模型,并对研究区内针叶林可燃物载量进行反演。结果表明:①基于Sentinel-1A数据提取的VH极化后向散射系数与针叶林可燃物载量有较高的相关性;②相比于单一数据源,联合Sentinel-1A和Sentinel-2A数据可显著提高针叶林可燃物载量估测精度,最优模型R^(2)分别提高了0.19、0.29,rRMSE分别降低4.66、6.94个百分点,RMSE分别降低了6.13、9.13 t/hm^(2),平均rRMSE分别降低了5.17、5.75个百分点,最优模型为SVR模型,其R^(2)=0.5,rRMSE=27.71,RMSE=36.47 t/hm^(2)。Sentinel-1A数据的加入有利于针叶林可燃物载量估测精度的提升。

若尔盖县主要林分可燃物载量特征及林火防控分析

按照《全国森林和草原火灾风险普查四川省试点调查技术指南》,分气候区、森林起源、龄组、郁闭度、优势树种对森林可燃物调查类型进行调查,分析确定火灾风险。根据林分型分层结果、面积比例和标准地数量要求,确定各类型布设调查标准地数量,再把各类型标准地分别布设在森林植被分布图上。按标准设置正方形标准地,开展乔木、灌木、草本、枯落物、腐殖质等可燃物载量调查。结果表明:各层次可燃物载量如下,乔木层153.04~302.28 t/hm^(2);灌木层8.30~19.03 t/hm^(2);草本层0.69~2.32 t/hm^(2);枯落物层3.33~4.74 t/hm^(2);腐殖层2.47~4.72 t/hm^(2);根据总可燃物载量比较,相同林分型中,随着林龄的增加,可燃物载量整体呈现上升趋势。云杉、桦木的成过熟林总可燃物载量比近熟林有所下降,这可能与当地人为砍伐等破坏有关;林分中最易引起火灾的可燃物为地表可燃物和草本植物。4种林分型下,平均死可燃物载量为5.66~9.18 t/hm^(2),发生较大火灾的可能性较小。但近熟林和成过熟林中的死可燃物载量较大,应重点关注。森林火灾引发的影响因子较多,应根据林分可燃物特征、立地条件、人文情况等实际情况,提出符合防火实情的防火区划和防火减灾策略。

北京西山林场侧柏林可燃物含水率及林火预测

以北京西山林场侧柏林为研究对象,对选择林分的特征进行调查,经内业试验对侧柏林地表细小可燃物含水率进行测定,选择通过Pearson相关性分析呈显著的气象因子为拟合变量建立细小可燃物含水率模型,根据引燃试验建立地表火发生概率模型,同时结合Cruz树冠火发生模型,利用实际气象条件对地表火与树冠火发生概率的动态变化进行分析。结果表明:侧柏林细小可燃物含水率模型预测效果较好;防火期内,侧柏林发生地表火的概率较大,而不同样地发生树冠火的概率差别较大,在风速较大时发生树冠火的概率较大。

滇东地区海寨林场针叶林地表可燃物潜在火行为研究

在海寨林场针叶林内设置样地,开展外业调查,采集地表凋落物并进行室内燃烧模拟和实验室理化性质分析,采用SPSS 26.0软件分析数据,探究海寨林场针叶林地表可燃物的特征及潜在火行为。杉木的绝对含水率为(9.40±0.65)%,热值最低为(19 878.9±48.63) kJ/kg,并且杉木的火强度和蔓延速度最小,分别为(259.64±19.73) kW/m和(0.33±0.14) m/min,所以杉木的燃烧性最差;云南松纯林可燃物载量为(0.27±0.12)kg/m2,热值为(21390.88±73.39)kJ/kg,火强度较低,为(307.26±15.83) kW/m,实际烧损率仅为(55.32±15.02)%,云南松的热值最大,容易引燃,但载量太低,无法维持正常燃烧;华山松纯林的热值低于云南松,且火强度和烧损率低于云南松-华山松混交林;云南松-华山松混交林的蔓延速度和火强度为(0.82±0.31) m/min和(564.14±13.53) kW/m,远高于其他3种,潜在火灾风险等级最高。由上述潜在火行为可知,海寨林场4种针叶林引发火灾的风险等级由高到低依次为云南松-华山松混交林、华山松纯林、云南松纯林和杉木。

基于通径分析的云南松林地表可燃物载量与林分因子的关系研究

[目的]研究林分因子对云南松林地表可燃物载量的影响,探讨林分因子对地表可燃物载量的作用机理及其关系,为研究区森林防火和地表可燃物管理提供科学依据。[方法]以雅安市汉源县为研究区域,在云南松林中设置标准地、样方,调查地表可燃物载量,对林分因子和地表可燃物载量关系进行分析。[结果]乔木层可燃物载量与郁闭度、林分密度和草本盖度显著相关;灌木层可燃物载量与灌木盖度显著相关;草本可燃物载量与郁闭度、林分密度和草本盖度显著相关;枯落物可燃物载量与郁闭度、林分密度、草本盖度和枯落物厚度显著相关;腐殖质可燃物载量与草本盖度和腐殖质厚度显著相关。平均胸径和平均树高对地表可燃物载量的直接影响较大,郁闭度、林分密度对地表可燃物载量的间接影响较大。[结论]云南松林林分因子通过直接和间接效应共同影响地表可燃物载量,其影响机理各不相同,在进行可燃物管理时,要因地制宜地选择可燃物管理方法以及调控措施。

陇南市主要森林类型死可燃物特征及危险性评价

【目的】探究陇南市主要森林类型死可燃物特征,并对森林火灾危险性进行评估,为区域森林火灾预防提供理论支撑。【方法】以陇南市4种主要森林类型为研究对象,分析不同森林类型死可燃物载量、干鲜比、平衡含水率、燃点和热值差异,并采用隶属函数模糊评价法对不同森林类型火灾危险性进行评价。【结果】4种森林类型死可燃物总载量呈油松林>落叶松林>栎类林>华山松林,且油松死可燃物总载量(16.02 t/hm2)显著高于其他3种森林类型(P<0.05),死可燃物中腐殖质和枯落物1载量显著高于枯落物2和枯落物3(P<0.05)。油松枯落物1死可燃物干鲜比显著高于落叶松(P<0.05),枯落物2死可燃物干鲜比最高(58.21%~66.47%),腐殖质最低(51.29%~55.56%)。栎类死可燃物平衡含水率最大,落叶松最小;枯落物3死可燃物平衡含水率最高(16.78%~20.38%),腐殖质层最低(12.22%~13.86%);死可燃物平衡含水率与可燃物直径成正比。腐殖质燃点显著高于枯落物,热值则与之相反(P<0.05)。隶属函数模糊评价结果表明4种森林类型中油松火灾危险性最大,其次是栎类和落叶松,华山松最低。【结论】不同森林类型和组分死可燃物载量、干鲜比、平衡含水率、燃点和热值存在差异。油松可燃物总载量最高,燃点和平衡含水率最低,导致其火灾危险性最大,因此在陇南市森林的经营和林火预防工作中,应加强对油松林可燃物管理。

甘肃天水关山林场森林可燃物特征调查与研究

调查分析了甘肃省天水市麦积区张家川县关山林场内不同森林类型中可燃物的特征,通过野外实地采样和实验室分析,测定了各类型森林可燃物的水分含量、热值和燃点等关键参数。结果表明:不同森林类型可燃物特性存在显著差异,关山林场总可燃物载量为冷杉林>桦木林>软阔混交林>灌木林;平均含水率软阔混交林>冷杉林>桦木林>灌木林的特征;燃点为桦木林>冷杉林>软阔混交林>灌木林的特征;热值为冷杉林>桦木林>软阔类混交林>灌木林的特征,且这些差异与森林所处的地形和局部气象条件也密切相关。

大娄山典型林分草本可燃物载量及其影响因素分析

以大娄山6种典型林分的草本可燃物为研究对象,通过对相同林分和不同林分下草本可燃物载量进行差异性及相关性分析,结合林分特征因子进行逐步回归分析,得到草本可燃物载量的预测模型。结果表明:阔叶混交林内草本可燃物载量最大值为0.759 t/hm^(2),杉木林最小,仅为0.058 t/hm^(2);马尾松林的草本可燃物载量主要与平均厚度相关,而阔叶混交林的草本可燃物载量主要受平均盖度和林分密度影响;相同林分时,马尾松林下模型的拟合优度为0.885,拟合效果较好,平均厚度、郁闭度和平均地径显著负向影响草本可燃物的载量;阔叶混交林下模型拟合优度为0.973,拟合效果好,平均盖度显著正向影响草本可燃物的载量。本研究对大娄山森林可燃物调控和科学林火管理具有重要意义。

低强度计划火烧对滇中地区云南松纯林可燃物的影响

在云南省中部的新平县照壁山云南松纯林内连续4年设置样地,通过外业调查、采样和实验室内实验,观测计划烧除时的火行为,以及计划烧除后的8个月左右对样地内的可燃物进行调查,可燃物包括乔木、灌木、草本和蕨类。结果表明:(1)计划烧除使得乔木的死亡率在10%以下;(2)计划烧除使得灌木、草本和蕨类的高度降低,降低了林内的垂直连续性,而2020年未进行计划烧除,灌木、草本和蕨类的高度有所增加,可见周期性计划烧除促进了林内植被生长;(3)计划烧除使得可燃物载量降低,能较有效地调控可燃物载量;(4)计划烧除使可燃物的种类减少,计划烧除内出现的物种,未计划烧除内均出现,未计划烧除的物种数大于计划烧除的物种数。研究结果能为云南计划烧除提供有利依据。

森林可燃物调控技术及其评价方法

森林可燃物作为森林燃烧三要素之一,其载量、燃烧特性和连续性分布均会影响林火的发生、蔓延和防控。森林可燃物作为林火发生的物质基础和必要条件,是林火蔓延的主要载体。一旦发生高强度火灾会严重破坏森林生态环境和森林资源。开展森林可燃物调控,减少可燃物积累,改善可燃物的燃烧特性以及改变其水平和垂直连续性,对降低林火风险,减小林火强度有重要意义。本文从可燃物调控技术(人工调控、机械清除、计划烧除、化学除草、微生物降解、营造生物防火林带等)和评价方法(林火行为、森林燃烧性、火灾风险和生态效应等)2方面,综述了国内外研究现状,总结归纳了森林可燃物调控技术和调控效果评价方法,对比了不同调控措施的有效性,分析了各种评价方法的优缺点。并对可燃物调控技术的未来研究方向和评价方法进行了展望,提出需要开展森林可燃物的基础研究,针对性探讨适宜重点火险区的调控措施,并长期监测和动态评估调控效果,量化调控效果的时间变化及生态环境影响。在理解阻火原理的基础上,提出以“绿色防火”理念结合森林生态调控等综合技术,助力实现“双碳”目标,是未来森林防火研究与管理的重要方向。

川西南地区云南松飞播林火灾研究

云南松是我国重要的造林绿化树种,也是西南地区飞播造林的主要树种之一,为国土绿化、森林覆盖率提高等发挥了重要作用。通过文献综述,分析云南松飞播林火灾危险性及特征,火灾形成条件和影响等。结果表明:现有云南松飞播林大部分是近熟林和成熟林,管护较好,林下可燃物载量大、连续性好,火源较多,火灾形成机制很复杂,火灾危险性高。要系统谋划飞播林的林下经济发展,生态优先,因地制宜,充分利用好林地资源,拓展林间、林下发展空间,将生态效益转化为经济效益。研究结果能更好总结现行云南松飞播林火管理政策和方法,提出与时俱进的飞播林火灾防控措施,为积极预防和安全扑救提供理论参考。