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1.
林火碳排放研究进展   总被引:2,自引:0,他引:2  
火是森林生态系统主要的干扰因子, 森林火灾的频繁发生不仅使森林生态系统遭到破坏, 同时也造成了含碳温室气体的大量释放。综述了火烧面积、森林可燃物以及燃烧效率等主要因子对森林火灾排放碳量估计的影响, 分析了这一领域未来研究发展趋势。大量研究表明:1)卫星遥感是估测大尺度上森林过火面积的主要手段, 随着高分辨率卫星的应用, 森林火灾面积的估计精度不断得到提高。目前的研究主要集中于大尺度上林火面积的估计和估算方法的改进。2)遥感数据是目前估计大尺度可燃物燃烧量的有效手段, 利用遥感数据的同时结合有效可燃物计算模型, 运用多元线性与非线性分析结合等方法提高对可燃物燃烧量的估计。3)燃烧效率是决定可燃物消耗量的主要因子, 也是估计森林火灾释放含碳气体量的关键。未来的研究是利用高分辨率的遥感数据, 结合复杂的可燃物计算模型, 更精确地估计林火碳排放。  相似文献   

2.
Abstract

Efficient transport of timber for supplying industrial conversion and biomass power plants is a crucial factor for competitiveness in the forest industry. Throughout the recent years minimizing driving times has been the main focus of optimizations in this field. In addition to this aim the objective of reducing environmental impacts, represented by carbon dioxide equivalent (CO2 e) emissions, is discussed. The underlying problem is formulated as a multi-depot vehicle routing problem with pickup and delivery and time windows (MDVRPPDTW) and a new iterative solution method is proposed. For the numerical studies, real-life data are used to generate test instances of different scales concerning the supply chain of biomass power plants. Small ones are taken to validate the optimality of the new approach. Medium and large test instances are solved with respect to minimizing driving times and fuel consumptions separately. This study shows that the selection of the objective of minimizing fuel consumption leads to a significant reduction of CO2 e emissions compared to a minimization of driving times.  相似文献   

3.
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.  相似文献   

4.
The paper focuses on the determination of fuel consumption (CO2 emission) and exhaust emissions such as CO, HC, NOx, and PM in the process of timber extraction and transport. A complex assessment of fuel consumption and exhaust emissions was performed for the entire, fully mechanized supply chain including, tree felling, delimbing, and bucking with a harvester, timber extraction with a forwarder and transport with a truck. The performed investigations determined unit exhaust emissions (referred to 1 m3 of timber) for the entire technological process and its individual stages. The investigations of the exhaust emissions and fuel consumption were performed under actual conditions of typical forest operations and transport. State-of-the-art portable emissions measurement system equipment was used for the measurements. The fuel consumption was determined through the carbon balance method. The investigations were performed for the process of extraction and transport of pulpwood. The measurements were performed on location in the town of B?bnik?t near Poznań, in a pinewood forest, typical of this part of Europe. The analysis includes the transport of timber to the lumberyard on a distance of 31.4 km. The total fuel consumption for the entire mechanized supply chain was 2.10 dm3/m3. The total exhaust emissions, however, amounted to: CO—8.91 g/m3, HC—1.19 g/m3, NOx—45.32 g/m3, PM—4.04 g/m3.  相似文献   

5.
We compared the greenhouse gas (GHG) emissions from a log pile (LP) to those from a sand compaction pile (SCP) and from cement deep mixing (CDM) as measures against soil liquefaction, assuming that forest and waste management scenarios influence the GHG (CO2, CH4, and N2O) balance of wood. We found little difference between the LP and SCP methods with respect to GHG emissions from fossil fuel and limestone consumption. However, GHG emissions from the CDM method were seven times higher than emissions from the LP method. In the GHG balance of wood, when the percentage of CH4 emissions from carbon in underground wood was lower than 3.3%, permanent storage in the log achieved greater reductions in GHG emissions than using the waste log as fuel in place of coal or heavy oil. In order to obtain reductions in GHG emissions by replacing SCPs or CDM with LPs, sustainable forest management with reforestation and prevention of CH4 emissions from the underground log are essential. Using reforestation, permanent storage of the log, no CH4 emission from the log, and using logging residues instead of coal, the LP can achieve reductions in GHG emissions of 121 tonnes of CO2 per 100 m2 of improvement area by replacing CDM.  相似文献   

6.
Pre-fire woody fuel (diameter > 0.6 cm) structure and its consumption by fire were measured at experimental/prescribed fires and high intensity wildfires in eucalypt forests in southern Australia in order to better understand and model the dynamics of woody fuel consumption. Two approaches were used in model development: (1) a fire or plot level analysis, based on a dataset which includes the proportion of the pre-fire woody fuel load consumed at each fire; and (2) a stage level analysis, based on a dataset where woody fuel consumption was measured at a woody fuel particle level (i.e. pre-fire and post-fire diameter). For the plot level analysis a generalised linear model (GLM) approach identified the Forest Fire Danger Index (FFDI) as the best predictor of the proportion of woody fuel consumed, with an R2 of 0.58 and mean absolute error of 10%. The stage level analysis recognised the various combustion stages through which a burning woody particle would pass, but failed to develop an accurate model that predicted the ignition, partial and full consumption of woody fuels based on fuel, fire behaviour and environmental variables. Analysis showed that consumption of woody fuel particles is highly variable and that variation in fire behaviour potentially has a greater impact on woody fuel consumption, than does variation in fuel characteristics (e.g. state of decay, fuel suspension and interactions with other fuel particles). The FFDI GLM provides forest and fire managers with a tool to manage woody fuel consumption objectives and may assist fire managers with forecasting post-frontal fire behaviour. The FFDI GLM may also assist forest and fire managers to better meet land management goals and to comply with air quality and emission targets.  相似文献   

7.
This paper summarizes the fuel type systems currently adopted by the fire danger rating systems or fire behavior prediction systems of some countries, such as Canada, the United States, Australia, Greece, and Switzerland. As an example, the Canadian Forest Fire Danger Rating System organizes fuel types into five major groups, with a total of 16 discrete fuel types recognized. In the United States National Fire Danger Rating System, fuel models are divided into four vegetation groups and twenty fire behavior fuel models. The Promethus System (Greece) divides fuels into 7 types, and Australia has adopted only three distinct fuel types: open grasslands, dry eucalyptus forests, and heath/shrublands. Four approaches to mapping fuels are acceptable: field reconnaissance, direct mapping methods, indirect mapping methods, and gradient modeling. Satellite remote-sensing techniques provide an alternative source of obtaining fuel data quickly, since they provide comprehensive spatial coverage and enough temporal resolution to update fuel maps in a more efficient and timely manner than traditional aerial photography or fieldwork. Satellite sensors can also provide digital information that can be easily tied into other spatial databases using Geographic Information System (GIS) analysis, which can be used as input in fire behavior and growth models. Various fuel-mapping methods from satellite remote sensing are discussed in the paper. According to the analysis of the fuel mapping techniques worldwide, this paper suggests that China should first create appropriate fuel types for its fire agencies before embarking on developing a national fire danger rating system to improve the current data situation for it's fire management programs.  相似文献   

8.
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.  相似文献   

9.
Fire behavior was measured and modeled from eight 1 ha experimental plots located in the Francis Marion National Forest, South Carolina, during prescribed burns on February 12 and February 20, 2003. Four of the plots had been subjected to mechanical chipping during 2002 to remove woody understory growth and to reduce large downed woody debris from the aftermath of Hurricane Hugo in 1989. The remaining four (control) plots were left untreated. The burns were low intensity (mean flame length = 36.2 cm) and slow moving (mean spread rate = 1.18 m min−1). Neither flame length nor rate of spread differed significantly between treatments (ANOVA F's < 0.5, P > 0.7, d.f. = 1,4). Post-burn observations provided somewhat more convincing evidence of treatment effects on fire behavior. According to transect data, only slightly more than half the area in the chip plots burned as compared to upwards of 80% in the burn-only plots. BehavePlus and Hough–Albini (HA) fire models correctly predicted the low intensity, slow moving fires given the observed wind and fuel moisture conditions. Accuracy of BehavePlus predictions depended on the value for fuel height entered in the model. Use of mean fuel height for the fuel depth parameter, as is typically recommended, somewhat overestimated fire hazard in the burn-only plots. However, limiting fuel height to the observed litter depth resulted in roughly accurate predictions. HA predictions for untreated fuels were close to correct even without adjusting fuel depth. When provided with two “high-risk” fuel and fire weather scenarios both models predicted more extreme fire behavior in the untreated fuels. In contrast, chipping appeared to protect against dangerous wildfires as long as fuel heights remained low. Smoke monitoring data from a companion study carried out in the same plots indicated a 60% reduction in smoke particulate production from chipped areas, roughly consistent with predictions of the fire effects model FOFEM. Mechanical chipping is apparently a useful method for limiting fire-hazard and smoke production in long-unburned fuels. However, questions remain concerning the long-term fate of heavy chip fuels and resultant effects on fire and smoke during severe drought.  相似文献   

10.
Wildland fire is a natural force that has shaped most vegetation types of the world. However, its inappropriate management during the last century has led to more frequent and catastrophic fires. Wildland fires are also recognized as one of the sources of CO2 and other greenhouse gases (GHG) that influence global climate change. As one of the techniques used to reduce the risk of destructive wildfires, prescribed burning has the potential of mitigating carbon emissions, and effectively contributes to the efforts proposed as part of the Clean Development Mechanism within the Kyoto protocol. In order to apply this concept to a real case, a simulation study was conducted in pine afforestation in the Andean region of Patagonia, Argentina, with the objective of evaluating the potential of prescribed burning for reducing GHG emissions. The scenario was established for a ten year period, in which simulated prescribed burning was compared to the traditional management scheme, which included the probability of annual average of wildfire occurrence based on available wildfire statistics. The two contrasting scenarios were: (1) managed afforestation, affected by the annual average rate of wildfires occurred in the same type of afforestation in the region, without prescribed burning, and (2) same as (1) but with the application of simulated prescribed burning. In order to estimate carbon stocks, and CO2 removals and emissions, we followed the guidelines given for GHG inventories on the Agriculture, Forestry and Other Land Uses (AFOLU) sector of the International Panel on Climate Change (IPCC), while the terminology used was the established by IPCC (2003). Data of afforested area, thinnings, and biomass growth were taken from previous surveys in the study area. Downed dead wood and litter (forest fuel load, FFL) was estimated adjusting equations fitted to those fuels, based on field data. Results show that comparing the two scenarios, prescribed burning reduced CO2 emissions by 44% compared to the situation without prescribed burning. The prescribed burning scenario represented about 12% of the total emissions (prescribed burning plus wildfires). Furthermore, avoided wildfires by simulated prescribed burning allowed an additional 78% GHG emissions mitigation due to extra biomass growth. Simulated prescribed burning in commercial afforestation of Patagonia appears to be an effective management practice not only to prevent wildfires, but also an efficient tool to mitigate GHG emissions. However, more studies in different scenarios would be needed to generalize these benefits to other ecosystems.  相似文献   

11.
Life-cycle analyses, energy analyses, and a range of utilization efficiencies were developed to determine the carbon dioxide (CO2) and fossil fuel (FF) saved by various solid wood products, wood energy, and unharvested forests. Some products proved very efficient in CO2 and FF savings, while others did not. Not considering forest regrowth after harvest or burning if not harvested, efficient products save much more CO2 than the standing forest; but wood used only for energy generally saves slightly less. Avoided emissions (using wood in place of steel and concrete) contributes the most to CO2 and FF savings compared to the product and wood energy contributions. Burning parts of the harvested logs that are not used for products creates an additional CO2 and FF savings. Using wood substitutes could save 14 to 31% of global CO2 emissions and 12 to 19% of global FF consumption by using 34 to 100% of the world’s sustainable wood growth. Maximizing forest CO2 sequestration may not be compatible with biodiversity. More CO2 can be sequestered synergistically in the products or wood energy and landscape together than in the unharvested landscape. Harvesting sustainably at an optimum stand age will sequester more carbon in the combined products, wood energy, and forest than harvesting sustainably at other ages.  相似文献   

12.

A computer-based model for the evaluation of energy use in mechanized wood harvesting systems (EnergyCalc) was developed with aid of life cycle analysis methodologies. The system boundaries were determined "from stump to roadside" with wood volume over bark (m3) as the functional unit. The computer model (based on a database system) used a Visual Basic program, and the energy audit was based on fuel and oil consumption, and the energy consumed in the manufacture of the machines and replacement parts. The general scenario from the literature, results from Sweden and a preliminary study from Ireland are presented. In the overall energy audit of mechanized wood harvesting systems in Ireland, fuel consumption was the most significant item (82%), followed by oils (7%) and machine repairs and replacement (11%). The mean energy use from the data for Ireland was found to be 16% higher than the equivalent in Sweden (120 vs 103 MJ m?3). An energy reduction strategy that has the potential to reduce overall energy consumption for Irish systems by up to 13% was suggested.  相似文献   

13.
ABSTRACT

Forest fires contribute to climate change mainly due to emission of greenhouse gases by biomass burning and loss of sequestration by sink destruction. The average contribution in Spain between 1998 and 2015 was 9,494,910 Mg CO2 eq per year, 23.8% from biomass burning and 76.2% from loss of carbon sequestration, the latter three times higher than the former, although the emissions from combustion are usually the only accounted. Regarding to the vegetation burned, 43.6% of emissions come from forest (17.7% conifers, 4.8% hardwoods and 21.1% Eucalyptus), 53.7% from scrublands and 2.7% from grasslands. The loss of sequestration is 6.6% in the fire year and by 93.4% in previous years. Scrubland burning produces a greater amount of emissions than forests, but forest regeneration is slower, with greater influence on the loss of sequestration. It is essential a forest management focused on increase fire resilience and adaptation to climate change, increase the effectiveness of extinction works to reduce fire damages and implement actions to recover the burnt vegetation, because the loss of sinks is a critical aspect.  相似文献   

14.
Due to increases in tree density and hazardous fuel loading in Sierra Nevadan forests, land management is focusing on fuel reduction treatments to moderate the risk of catastrophic fires. Fuel treatments involving mechanical and prescribed fire methods can reduce surface as well as canopy fuel loads. Mastication is a mechanical method which shreds smaller trees and brush onto the surface fuel layer. Little data exist quantifying masticated fuel beds. Despite the paucity of data on masticated fuels, land managers desire fuel loading, potential fire behavior and fire effects such as tree mortality information for masticated areas. In this study we measured fuel characteristics before and after mastication and mastication plus prescribed burn treatments in a 25-year old ponderosa pine (Pinus ponderosa C. Lawson) plantation. In addition to surface fuel characteristics and tree data collection, bulk density samples were gathered for masticated material. Regressions were created predicting masticated fuel loading from masticated fuel bed depth. Total masticated fuel load prior to fire treatment ranged from 25.9 to 42.9 Mg ha−1, and the bulk density of masticated fuel was 125 kg m−3. Mastication treatment alone showed increases in most surface fuel loadings and decreases in canopy fuel loads. Masticated treatment in conjunction with prescribed burning reduced both surface and canopy fuel loads. Detailed information on fuel structure in masticated areas will allow for better predictions of fire behavior and fire effects for fire in masticated fuel types. Understanding potential fire behavior and fire effects associated with masticated fuels will allow managers to make decisions on the possibility of mastication to create fuel breaks or enhance forest health.  相似文献   

15.
A study was done using eight different logging machines (harvesters and forwarders) in clear-felling operations to quantify the associated fuel consumption, and to define the inherent relationship between engine output power and fuel consumption. Exhaust emissions were also calculated on the basis of mean fuel consumption values, obtained by measurements, and from the developed regression and correlation model for diesel and rapeseed methyl ester (RME) fuels. The calculation considered exhaust emissions associated with the manufacture, distribution, and combustion of the respective fuels. It was found that carbon dioxide emissions amounted to 9.63 kg/m3 of delivered timber for diesel fuel, and to 10.64 kg/m3 for RME. It was also found that when using RME only 2.82 kg/m3 of carbon dioxide emissions originated from fossil resources, therefore, it is only this amount that can be deemed an environmental load, confirming RME as a lesser environmental pollutant.  相似文献   

16.
Fire histories contribute important information to contemporary fire planning, however, our knowledge is not comprehensive geographically. We evaluated the influence of topography on fire history patterns in two contrasting landscapes within the Santa Catalina Mountains of southeastern Arizona. Multiple fire-scarred trees from randomly selected 2-ha plots were used to develop plot composite mean fire intervals (PCMFIs) within the Butterfly Peak (BP) and Rose Canyon (RC) landscapes. BP is dominated by steep, northerly aspects and presence of potential fire spread barriers (exposed rock bluffs and scree slopes). RC is dominated by more gentle and southerly aspects with relatively few fire barriers. Within each landscape, PCMFIs did not differ significantly between aspect classes from A.D. 1748 to 1910 (BP: p = 0.73 and RC: p = 0.57). Pooled PCMFIs in the gentler RC landscape were, however, significantly shorter (p < 0.001) than in the steeper BP landscape. The frequency of relatively widespread fires (i.e., number of fire years when ≥2 plots scarred) was similar between landscapes, but fires in the gentler RC landscape were significantly larger (p = 0.033). The higher frequency of large fires (i.e., fires that burned >75% of the landscape) in RC resulted in more area burned over time and shorter fire intervals at individual plots. Conversely, smaller fires in the dissected BP landscape resulted in less area burned and longer periods between fires at individual plots. The different topographies in the two landscapes likely result in different wind intensities, fuel moistures, and fuel/vegetation types—and consequently, different historical fire spread patterns. Our conclusion is that fire history patterns are not influenced primarily by stand-scale topography, but rather by the topographic characteristics of the broader, surrounding landscape.  相似文献   

17.
Summary

Land managers need vegetation maps to inventory, monitor, and manage ecological resources across multiple spatial and temporal scales. Current vegetation maps usually only describe one vegetation characteristic, such as cover types, across the landscape. Although these maps provide important information for land management, they often fall short of addressing key issues like forest health and ecosystem management. In this paper we present an integrated approach where three different vegetation classifications are used in concert to spatially characterize many ecological attributes such as snag densities, insect susceptibility, and fire behavior across the landscape. Two examples from the Pacific Northwest are used to illustrate how this approach can be used to describe fuel characteristics and resource hazard across multiple scales.  相似文献   

18.
Fire is a major disturbance in forests and one of the most important carbon emissions sources, which contributes to climate change. Carbon emissions are directly correlated with the degree of organic matter consumption or fire severity. Gaining knowledge about the relative strength of the various explanatory variables is essential to mitigate its environmental impact. We tested an approach that combines wind modeling, light detection and ranging (LiDAR), remotely sensed vegetation indices and topography data for assessing the occurrence of high-severity fire using the random forests ensemble learning method. Data from four wildfires that occurred in Galicia (northwestern Spain) were used to exemplify the application of this approach. The models predicted high-severity occurrence with a classification accuracy ranging from 77 to 94%. High-severity fire occurred more frequently in areas of high simulated wind speed, and more pronouncedly, for cases reported as wind-driven fires. High severity also occurred more frequently in areas of high terrain roughness, on sunny slopes and in low canopy base height stands. This approach allowed predicting spatially explicit fire severity at a mean scale level (resolution of 25 m) with accuracy rates from 80 to 95%. This approach may be helpful for fire managers when delimiting and planning fuel treatments for severity mitigation or during fire suppression, and for post hoc case studies.  相似文献   

19.
利用GIS划分黑龙江省森林可燃物类型区   总被引:7,自引:0,他引:7  
本文采用黑龙江省各县的森林覆盖率、森林可燃物载量、林木组成、海拔、防火期月平均气温、相对湿度、风速和降水量8个因子,通过权重和累计概率的方法,应用ARC/INFO技术,并采用矢量图形法中的栅格数据矢量化法,把黑龙江省森林分布图和黑龙江省行政区划图绘成电子地图,然后将其叠加,再转换成大地坐标,从中提取相关数据,最后划分了5个等级的可燃物类型区。全省81个县(林业局)中一、二、三、四和五级森林可燃物类型区分别占全省总数的16%、17%、17%、11%、38%。一级森林可燃物类型区集中在大、小兴安岭、张广才岭、老爷岭等山地林区;五级森林可燃物类型区主要集中分布在松嫩平原、三江平原等地区;其它三种级别的森林可燃物类型区介于平原与山地之间。图2表4参8。  相似文献   

20.
Using intumescent coatings on wood-based materials is an effective method for fire safety. Previous studies have demonstrated that the formulation of components strongly influences the performance of coatings. This study investigated the effect of intumescent formulation of vinyl acetate-acrylic coating on flame retardancy of plywood. The fire retardancy of materials was assessed by both heat release and CO and CO2 emissions. The CO and CO2 emissions have not been used frequently to rank materials; the highly toxic CO and CO2 may cause most fire fatalities. The fire retardancy of coatings on plywood was assessed by a cone calorimeter. Total heat release and time to peak heat release rate were the two primary parameters. The data show that low contents of binder resin (BR) and foam producing substance (FPS) decreased total heat release and lengthened time to peak heat release rate. Additionally, low BR and FPS content can form an ideal char layer. The ideal char layer significantly decreased the CO and CO2 emission. The mechanism to achieve better fire performance was verified by thermogravimetrical analysis exhibiting lower weight loss. Moreover, evaluated by 31P NMR, the low BR and FPS content can extend the survival duration of phosphor-carbonaceous chars. The results provide information for designing vinyl acetate-acrylic emulsion coating.  相似文献   

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