Forest fuel mapping and evaluation of LANDFIRE fuel maps in Boulder County,Colorado, USA

A key challenge in modern wildfire mitigation and forest management is accurate mapping of forest fuels in order to determine spatial fire hazard, plan mitigation efforts, and manage active fires. This study quantified forest fuels of the montane zone of Boulder County, CO, USA in an effort to aid wildfire mitigation planning and provide a metric by which LANDFIRE national fuel maps may be compared. Using data from 196 randomly stratified field plots, pre-existing vegetation maps, and derived variables, predictive classification and regression tree models were created for four fuel parameters necessary for spatial fire simulation with FARSITE (surface fuel model, canopy bulk density, canopy base height, and stand height). These predictive models accounted for 56–62% of the variability in forest fuels and produced fuel maps that predicted 91.4% and 88.2% of the burned area of two historic fires simulated in the FARSITE model. Simulations of areas burned based on LANDFIRE national fuel maps were less accurate, burning 77.7% and 40.3% of the historic fire areas. Our results indicate that fuel mapping efforts that utilize local area information and biotic as well as abiotic predictors will more accurately simulate fire spread rates and reflect the inherent variability of forested environments than do current LANDFIRE data products.     

Stand structure, fuel loads, and fire behavior in riparian and upland forests, Sierra Nevada Mountains, USA; a comparison of current and reconstructed conditions

Fire plays an important role in shaping many Sierran coniferous forests, but longer fire return intervals and reductions in area burned have altered forest conditions. Productive, mesic riparian forests can accumulate high stem densities and fuel loads, making them susceptible to high-severity fire. Fuels treatments applied to upland forests, however, are often excluded from riparian areas due to concerns about degrading streamside and aquatic habitat and water quality. Objectives of this study were to compare stand structure, fuel loads, and potential fire behavior between adjacent riparian and upland forests under current and reconstructed active-fire regime conditions. Current fuel loads, tree diameters, heights, and height to live crown were measured in 36 paired riparian and upland plots. Historic estimates of these metrics were reconstructed using equations derived from fuel accumulation rates, current tree data, and increment cores. Fire behavior variables were modeled using Forest Vegetation Simulator Fire/Fuels Extension.Riparian forests were significantly more fire prone under current than reconstructed conditions, with greater basal area (BA) (means are 87 vs. 29 m²/ha), stand density (635 vs. 208 stems/ha), snag volume (37 vs. 2 m³/ha), duff loads (69 vs. 3 Mg/ha), total fuel loads (93 vs. 28 Mg/ha), canopy bulk density (CBD) (0.12 vs. 0.04 kg/m³), surface flame length (0.6 vs. 0.4 m), crown flame length (0.9 vs. 0.4 m), probability of torching (0.45 vs. 0.03), predicted mortality (31% vs. 17% BA), and lower torching (20 vs. 176 km/h) and crowning indices (28 vs. 62 km/h). Upland forests were also significantly more fire prone under current than reconstructed conditions, yet changes in fuels and potential fire behavior were not as large. Under current conditions, riparian forests were significantly more fire prone than upland forests, with greater stand density (635 vs. 401 stems/ha), probability of torching (0.45 vs. 0.22), predicted mortality (31% vs. 16% BA), and lower quadratic mean diameter (46 vs. 55 cm), canopy base height (6.7 vs. 9.4 m), and frequency of fire tolerant species (13% vs. 36% BA). Reconstructed riparian and upland forests were not significantly different. Our reconstruction results suggest that historic fuels and forest structure may not have differed significantly between many riparian and upland forests, consistent with earlier research suggesting similar historic fire return intervals. Under current conditions, however, modeled severity is much greater in riparian forests, suggesting forest habitat and ecosystem function may be more severely impacted by wildfire than in upland forests.     

汽车燃料消耗量道路试验误差分析及控制

对汽车在道路条件下进行燃料消耗量试验时.影响燃料消耗量测量的主要因素及误差做了全面的分析。并提出了控制误差的主要措施。     

Dynamic prediction of forest fuel loads by Grey Verhulst model

The variation of fuel loads after a fire for three forest types,phododendron--Larix gmelinii forest,herb--Larix gmelinii forest andherb--Betula platyphlla 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, inflammable fuel and the total fuels in each forest type. After a fire, the inflammable fuel loads inphododendron-Lxirix gmelinii forest and in the herb- -Betula platyphlla fores was estimated at 10.958 t/hm² and 10.473 t/hm² respectively, by 13 years later, and that was 12.297 t/hm² inherb--Larix gmelinii forest by 7 years later. It was predicated that a big fire may occur after 10 years based on inflammable fuel biomass accumulated.     

The impact of road geometry and surface roughness on fuel consumption of logging trucks

Fuel accounts for more than 35% of transport costs in Swedish forestry, and reduced fuel consumption would provide immediate economic and environmental benefits. The objective of this study was to quantify the effect of road gradient, curvature and surface roughness on fuel consumption of a conventional 60-ton logging truck. The study used a 320-km test track on both public and forest roads. The track was driven with various load weights in both dry summer and wet autumn conditions. Fuel consumption data were retrieved from the truck's CAN-bus system, and road data were measured with a profilograph. Average fuel consumption was 71.4?litres/100?km. A regression analysis showed that the most important factor was the interaction between vehicle weight and gradient, explaining the 86% increase between empty and fully loaded truck. In addition, the regression analysis quantified the individual effects of undulation, curvature and surface roughness, explaining the 107% increase in fuel consumption between the highest and lowest road class. Results from the proposed regression model (R² of 84% for a road section length of 1000?m) were consistent with predictions given by the European ARTEMIS model, and the proposed model can be used to improve cost estimation and route selection.     

Short-term response of reptiles and amphibians to prescribed fire and mechanical fuel reduction in a southern Appalachian upland hardwood forest

We compared the effects of three fuel reduction techniques and a control on the relative abundance and richness of reptiles and amphibians using drift fence arrays with pitfall and funnel traps. Three replicate blocks were established at the Green River Game Land, Polk County, North Carolina. Each replicate block contained four experimental units that were each approximately 14 ha in size. Treatments were prescribed burn (B); mechanical understory reduction (M); mechanical + burn (MB); and controls (C). Mechanical treatments were conducted in winter 2001–2002, and prescribed burns in March 2003. Hot fires in MB killed about 25% of the trees, increasing canopy openness relative to controls. Leaf litter depth was reduced in B and MB after burning, but increased in M due to the addition of dead leaves during understory felling. The pre-treatment trapping period was short (15 August–10 October 2001) but established a baseline for post-treatment comparison. Post-treatment (2002–2004), traps were open nearly continuously May–September. We captured a total of 1308 species of 13 amphibians, and 335 reptiles of 13 species. The relative abundance of total salamanders, common salamander species, and total amphibians was not changed by the fuel reduction treatments. Total frogs and toads (anurans) and Bufo americanus were most abundant in B and MB; however, the proximity of breeding sites likely affected our results. Total reptile abundance and Sceloporus undulatus abundance were highest in MB after burning, but differed significantly only from B. Mean lizard abundance in MB was highest in 2004 and higher than in other treatments, but differences were not statistically significant. Our results indicate that a single application of the fuel reduction methods studied will not negatively affect amphibian or reptile abundance or diversity in southern Appalachian upland hardwood forest. Our study further suggests that high-intensity burning with heavy tree-kill, as in MB, can be used as a management tool to increase reptile abundance – particularly lizards – with no negative impact on amphibians, at least in the short-term.     

Comparing the role of fuel breaks across southern California national forests

Fuel treatment of wildland vegetation is the primary approach advocated for mitigating fire risk at the wildland-urban interface (WUI), but little systematic research has been conducted to understand what role fuel treatments play in controlling large fires, which factors influence this role, or how the role of fuel treatments may vary over space and time. We assembled a spatial database of fuel breaks and fires from the last 30 years in four southern California national forests to better understand which factors are consistently important for fuel breaks in the control of large fires. We also explored which landscape features influence where fires and fuel breaks are most likely to intersect. The relative importance of significant factors explaining fuel break outcome and number of fire and fuel break intersections varied among the forests, which reflects high levels of regional landscape diversity. Nevertheless, several factors were consistently important across all the forests. In general, fuel breaks played an important role in controlling large fires only when they facilitated fire management, primarily by providing access for firefighting activities. Fire weather and fuel break maintenance were also consistently important. Models and maps predicting where fuel breaks and fires are most likely to intersect performed well in the regions where the models were developed, but these models did not extend well to other regions, reflecting how the environmental controls of fire regimes vary even within a single ecoregion. Nevertheless, similar mapping methods could be adopted in different landscapes to help with strategic location of fuel breaks. Strategic location of fuel breaks should also account for access points near communities, where fire protection is most important.     

马尾松人工林地表可燃物负荷量动态模型的研究

设立64块标准地,应用回归分析,建立马尾松(Pinus massonianaLamb)林分地表可燃物载量与主要林分因子动态关系的数学模型。检验结果表明,林分因子对马尾松林分地表可燃物载量变化有极显著的影响,林分郁闭度主要影响地表1h时滞可燃物载量变化,林分平均年龄主要影响地表10 h时滞可燃物载量的变化。在实际中拟合效果良好,可用于预测马尾松人工林地表可燃物载量的动态规律,为地表可燃物管理提供科学的依据。     

阻燃处理木材的热分析

为研究阻燃处理对木材热解过程的影响,将未处理的和经过阻燃处理的木材进行热分析(包括TG、DTG、DSC),其结果表明:阻燃处理可改变木材发生剧烈热分解时的温度和重量损失速率,并使400℃时的残留物重量明显增加,在20～450℃范围内,未处理木材的DSC图谱有三个峰,相应于三个不同的热解阶段;不同阻燃剂的加入可明显地改变DSC图谱的峰形和峰位,即改变了木材的燃烧性能。此外本文还结合实验结果,对阻燃剂的作用机理提出了初步解释。     

Objectives and considerations for wildland fuel treatment in forested ecosystems of the interior western United States

Many natural resource agencies and organizations recognize the importance of fuel treatments as tools for reducing fire hazards and restoring ecosystems. However, there continues to be confusion and misconception about fuel treatments and their implementation and effects in fire-prone landscapes across the United States. This paper (1) summarizes objectives, methods, and expected outcomes of fuel treatments in forests of the Interior West, (2) highlights common misunderstandings and areas of disagreement, and (3) synthesizes relevant literature to establish a common ground for future discussion and planning. It is important to understand the strengths and limitations of fuel treatments to evaluate their potential to achieve an objective, develop sensible fire management policies, and plan for their effective use. We suggest that, while the potential of fuel treatment to reduce wildfire occurrence or enhance suppression capability is uncertain, it has an important role in mitigating negative wildfire effects, increasing ecosystem resilience and making wildfire more acceptable.     

Economic analysis of harvesting behavior using the modified Gentan probability theory

In the past studies on the Gentan probability theory, economic factors, such as the price of logs and the interest rate, have not been embedded into the derived stochastic model due to the limitation of the underlying assumptions. This has lead to misleading results of economic analysis for harvesting behavior based on the Gentan probability theory. In this paper, economic analysis of harvesting behavior was conducted by extending the Gentan probability theory. Since the proposed stochastic process can incorporate a nonstationary growth function, economic analysis of harvesting behavior was easily implemented. Experimental analysis of economic factors showed that change in the price of logs, the interest rate and harvest related costs affected the Gentan probability distribution. Although the analysis is still hypothetical, the results imply the potential use of the Gentan probability theory to predict the forest owners' harvesting behavior.     

Yellow pine regeneration as a function of fire severity and post-burn stand structure in the southern Appalachian Mountains

We used pre- and post-burn fire effects data from six prescribed burns to examine post-burn threshold effects of stand structure (understory density, overstory density, shrub cover, duff depth, and total fuel load) on the regeneration of yellow pine (Pinus subgenus Diploxylon) seedlings and cover of herbaceous vegetation in six prescribed-fire management units located within western Great Smoky Mountains National Park (GSMNP) in east Tennessee, USA. We also evaluated the utility of the Keetch-Byram Drought Index (KBDI) as a predictor of post-burn stand and fuel conditions by comparing post-burn stand variables for different ranges of KBDI (23-78; more wet, and 328-368; more dry). We found that yellow pine seedlings were effectively absent in post-burn forests until overstory density was reduced over 40%, understory density was reduced over 80%, and post-burn shrub cover was 10% or less. We also observed that a reduction in total fuels of 60% and a post-burn duff layer depth of less than four cm were required for successful regeneration of yellow pine. Total herbaceous species cover exhibited near identical responses with increased cover following an 80% reduction in understory density and a post-burn duff depth of less than 4 cm. We observed strong positive relationships between high KBDI values and burn severity, changes in forest structure, reductions in fuels, and post-burn yellow pine reproduction. We observed continuous recruitment of yellow pine seedlings 5 years after fire in high KBDI burns while low KBDI burns showed little change in yellow pine density through time. An intense outbreak of the southern pine beetle (SPB; Dendroctonus frontalis) occurred within 2 years of our high KBDI burns and reduced shading resulting from overstory mortality likely enhanced the survival of yellow pine seedlings. The results of this study provide targets for the application of prescribed fire to restore yellow pine in the southern Appalachians. Continued research and monitoring will help determine how prescribed fire can best be applied in combination with other disturbance agents such as SPB to perpetuate yellow pine forests.     

基于LIDAR点云的建筑物的三维建模

介绍建筑物建模常用的3种方法(航空摄影、依图而建和机载激光扫描)及其优缺点,采用多种数据源和多种技术手段相结合的方式进行建筑物三维模型构建.对三维体框模型和三维精细模型构建等具体的数据处理过程进行了论述.认为基于三维激光雷达技术制作的三维模型精度高、适用范围广、外业工作量少,省时省力,但其数据量大,信息数据的存储、快速传输及浏览等目前都还较困难.     

云南松可燃物载量预测模型研究

对安宁市不同乡镇云南松林的17块样地可燃物载量与郁闭度、胸径、树高、林龄等林分因子和坡度、坡位、坡向等地形因子进行了野外调查和室内实验分析与计算。应用SYSTAT统计软件,对云南松可燃物载量与林分和地形因子进行回归分析,并建立了数学模型,利用这些特征因子来推算云南松林可燃物的载量,取得较为满意的结果。     

Fire models and methods to map fuel types: The role of remote sensing

Understanding fire is essential to improving forest management strategies. More specifically, an accurate knowledge of the spatial distribution of fuels is critical when analyzing, modelling and predicting fire behaviour. First, we review the main concepts and terminology associated with forest fuels and a number of fuel type classifications. Second, we summarize the main techniques employed to map fuel types starting with the most traditional approaches, such as field work, aerial photo interpretation or ecological modelling. We pay special attention to more contemporary techniques, which involve the use of remote sensing systems. In general, remote sensing systems are low-priced, can be regularly updated and are less time-consuming than traditional methods, but they are still facing important limitations. Recent work has shown that the integration of different sources of information and methods in a complementary way helps to overcome most of these limitations. Further research is encouraged to develop novel and enhanced remote sensing techniques.     

Factor analysis of risk-taking behavior in forest work

In this study, the data obtained by a questionnaire survey were analyzed to examine the difference with the type of occupation, consistency in each situation, the inductive and restraint factors of the risk-taking behavior in the forest work to elucidate the risk-taking behavior in forest work. The results showed that (1) the Kyushu Forest Cooperative Association’s staff members underestimate the risk, but have a strong recognition of “law observance,” (2) the supervisor or instructor has low consciousness of risk, (3) as the inductive factor of behavior, one’s own benefit in the daily situation is given the highest priority, but risk is the most important factor in situations concerning forest work and forest machine operation and handling, irrespective of the accuracy of the risk evaluation, (4) as the restraint factor of behavior, although there is a difference in the risk evaluation whether large or small, risk is given priority by all workers, and (5) the dare probability of each risk-taking behavior is highly correlated with the risk evaluation of the behavior. Among others, low consciousness of the supervisor or instructor concerning safety management is pointed out as a main factor in worker’s accidents, and reconsideration of the relationship between the supervisor or instructor and workers is necessary.