An easy,accurate and efficient procedure to create forest fire risk maps using the SEXTANTE plugin Modeler

To prevent, detect, and protect against forest fires, forest personnel need to define rules for determining forest fire risk. In Portugal, all municipalities must annually produce forest fire risk(FFR) maps. To produce more reliable FFR maps more easily, we developed an open source model using the Modeler plugin of SEXTANTE in the program QGIS version 2.0 Dufour. The model provides all the maps involved in the FFR model(susceptibility map, hazard map, vulnerability map, economic value map,and potential loss map) and was produced according to Portuguese Forest Authority's(AFN, Autoridade Florestal Nacional) rules for determining the FFR. This model was tested for the Portuguese municipality Santa Maria da Feira, where 40 % of the total municipality area falls in the category ‘‘very high' or ‘‘high' fire risk. The ‘‘very high'fire risk area is mainly classified as broad-leaved forest and has the steepest slopes(15 %). The distance of burned areas to roads was also analyzed; the proportion of burned areas increased with increasing distance to the main roads.In addition, 92.6 % of the ‘‘high' and ‘‘very high' risk zones were located in areas with lower elevation. These results confirmed that forest fire is strongly influenced not only by environmental factors but also by anthropogenic factors. The procedure implemented here was compared with our open source application already available in QGIS and also to the same procedure implemented in GIS proprietary software. Although the results were obviously the same, the model developed here presents several advantages over the other two approaches. Besides being faster,it is easy to change the model parameters according to user needs(i.e., to the rules of different countries), and can be modified and adapted to other variables and other areas to create risk maps for different natural phenomena(e.g.,floods, earthquakes, landslides). The model is easy to use and to create risk and hazard maps rapidly in a free, open source environment that does not require any programming knowledge.     

A comparative analysis of spatial, temporal, and ecological characteristics of forest fires in seasonally dry tropical ecosystems in the Western Ghats, India

The Western Ghats in India is one of the 25 global hotspots of biodiversity, and it is the hotspot with the highest human density. This study considers variations in the regional fire regime that are related to vegetation type and past human disturbances in a landscape. Using a combination of remote sensing data and GIS techniques, burnt areas were delineated in three different vegetation types and various metrics of fire size were estimated. Belt transects were enumerated to assess the vegetation characteristics and fire effects in the landscape. Temporal trends suggest increasingly short fire-return intervals in the landscape. In the tropical dry deciduous forest, the mean fire-return interval is 6 years, in the tropical dry thorn forest mean fire-return interval is 10 years, and in the tropical moist deciduous forest mean fire-return interval is 20 years. Tropical dry deciduous forests burned more frequently and had the largest number of fires in any given year as well as the single largest fire (9900 ha). Seventy percent, 56%, and 30% of the tropical moist deciduous forests, tropical dry thorn forests, and tropical dry deciduous forests, respectively have not burned during the 7-year period of study. The model of fire-return interval as a function of distance from park boundary explained 63% of the spatial variation of fire-return interval in the landscape. Forest fires had significant impacts on species diversity and regeneration in the tropical dry deciduous forests. Species diversity declined by 50% and 60% in the moderate and high frequency classes, respectively compared to the low fire frequency class. Sapling density declined by ca. 30% in both moderate and high frequency classes compared to low frequency class. In tropical moist deciduous ecosystems, there were substantial declines in species diversity, tree density, seedling and sapling densities in burned forests compared to the unburned forests. In contrast forest fires in tropical dry thorn forests had a marginal positive effect on ecosystem diversity, structure, and regeneration.     

东莞大屏嶂森林火险等级评价与区划

针对广东省东莞大屏嶂森林公园的森林资源环境特点,选取植被类型、坡度、坡向、海拔、居民区距离、道路距离6个火险影响因子,利用GIS空间分析功能对大屏嶂森林公园进行森林火险等级的评价与区划。区划方案表明,该区可以划分为无、低、中、高和极高5个等级火险区,其面积分别占研究区的1.67%、2.19%、33.16%、55.3%和7.68%。森林火险等级的空间分异较明显,极高火险主要出现在西北部,中部和北部火险等级较高,东部与南部火险稍低。森林火险较高等级主要受植被类型、坡向及海拔这3个因素影响。     

龙胜县森林火险等级区

以广西龙胜县为研究区,调查分析该县森林火险状况及影响要素,结合森林资源载量及森林防火实际,选取树种（组）燃烧类型、人口密度、气象因子、火灾次数等11项主要林火影响因子,综合运用层次分析法(AHP)、聚类分析法及ArcGIS空间分析法,区划森林火险等级。结果表明,各村（分场）可区划为Ⅰ（高火险区）、Ⅱ（中火险区）、Ⅲ（低火险区）3个火险等级;Ⅰ、Ⅱ、Ⅲ级火险区面积分别占研究区总面积的35.47%、38.33%、26.20%。高火险区主要分布在东部和南部,中火险区集中于西部和北部,低火险区分散在高、中火险区之间。区划结果有利于总结、突出研究区森林火情特点和重点。     

Forest fire risk zone mapping from satellite images and GIS for Baihe Forestry Bureau, Jilin, China

A forest fire can be a real ecological disaster regardless of whether it is caused by natural forces or human activities, it is possible to map forest fire risk zones to minimize the frequency of fires, avert damage, etc. A method integrating remote sensing and GIS was developed and applied to forest fire risk zone mapping for Baihe forestry bureau in this paper. Satellite images were interpreted and classified to generate vegetation type layer and land use layers （roads, settlements and farmlands）. Topographic layers （slope, aspect and altitude） were derived from DEM. The thematic and topographic information was analyzed by using ARC/INFO GIS software. Forest fire risk zones were delineated by assigning subjective weights to the classes of all the layers （vegetation type, slope, aspect, altitude and distance from r3ads, farmlands and settlements） according to their sensitivity to fire or their fire-inducing capability. Five categories of forest fire risk ranging from very high to very low were derived automatically. The mapping result of the study area was found to be in strong agreement with actual fire-affected sites.     

连云港花果山森林景区高分辨率火险区划

利用10cm高空间分辨率航空遥感影像,在森林资源二类调查的基础上,获取研究区的可燃物类型及其特征信息;利用1∶10 000地形图获取地形因子信息。在此基础之上,通过加权叠置法计算火险指数,并将研究区划分为Ⅰ级(没有危险)、Ⅱ级(低度危险)、Ⅲ级(中度危险)、Ⅳ级(高度危险)、Ⅴ级(极度危险)等5个火险区划。结果表明:Ⅰ级火险区面积最小,占研究区总面积3.98%;Ⅱ级火险区面积最大,占32.25%;Ⅲ级火险区面积占21.05%;Ⅳ级和Ⅴ级火险区面积分别占22.14%和20.58%,两者之和较大,占研究区总面积的42.72%,研究区防火任务艰巨。研究区内可燃物类型对火险等级划分起重要作用,其中麻栎和茶树在森林防火工作中发挥重要作用;松树、竹林和荒草地是防火的重点。     

基于粒子群算法和BP神经网络的多因素林火等级预测模型

针对现有小尺度林火预测模型预测结果有效性、可扩展性等方面的不足,通过考虑多种火险因素,构建BP神经网络预测模型以提高预测精度,在此基础上借助粒子群算法加快BP神经网络收敛速度,进而提出一种混成的多因素森林火险等级预测模型particle swarm optimization based back-propagation neural network (PSO-BP)。所构建的预测模型,能够同时考虑气候因素(日最高气温、日平均气温、24 h降水量、连旱天数、日照时数、日平均相对湿度、日平均风速)、地形地貌因素(海拔、坡度、坡向、土壤含水量)、可燃物因素(植被类型、可燃物含水率、地被物载量)、人为因素(人口密度、距人类活动区域的距离) 16个变量。基于南京林业大学下蜀林场森林防火实验站传感器网络所采集的实际数据及现场测量数据,通过一组试验验证提出模型的有效性。结果表明:基于训练数据集及检验样本所构建的模型能够开展有效的火险等级预测;模型的计算复杂度较单独使用BP神经网络模型明显下降。     

Integrating fire risk considerations in landscape-level forest planning

The low timber returns of Mediterranean forests, together with their high fire risk, has led to negligent forest management. Absence of management has in turn been blamed for increasing the risk of fire, thus forming a vicious circle of low profitability, little management and high risk of fire. Developing forest planning tools that maximize both economic objectives and fire resistance could help to revive the forest sector in the region and generate long-term fire prevention strategies. In the present study, we simultaneously maximized timber income and the overall fire resistance of the landscape to generate management plans for a typical forest landscape in the Pre-Pyrenees of Catalonia (North-East Spain). The risk of fire was integrated into the economic objective by incorporating potential fire losses in the expected net income. Landscape metrics describing fire resistance were also included in problem formulations. The results show that this approach greatly improves management efficiency in terms of economic profitability and fire resistance.     

基于RS和GIS的香格里拉森林火险等级区划

以三江并流核心区香格里拉市为研究对象,以TM影像、森林资源调查数据、林相图和DEM为信息源,在分析香格里拉地区森林火险因子基础上,选取植被类型、坡向、坡度、海拔和离居民点远近作为主要林火等级区划因子。借助RS和GIS技术并采用因子加权叠置法,对研究区森林火险情况进行了定量评价,将火险等级分为低、中、高3类。结果表明:研究区低、中、高火险区面积分别占研究区总面积的12.96%,47.85%,38.87%,中、高火险区比重较大,森林防火任务较重。高火险区大部分位于易燃树种区和居民点密集区域,树种燃烧性和人为因素是影响火灾的重要因子,研究结果可为相关部门森林防火提供技术支持。     

Forest fire risk assessment in parts of Northeast India using geospatial tools

Forest fire is a major cause of changes in forest structure and function. Among various floristic regions, the northeast region of India suffers maximum from the fires due to age-old practice of shifting culti- vation and spread of fires from jhum fields. For proper mitigation and management, an early warning of forest fires through risk modeling is required. The study results demonstrate the potential use of remote sens- ing and Geographic Information System (GIS) in identifying forest fire prone areas in Manipur, southeastern part of Northeast India. Land use land cover (LULC), vegetation type, Digital elevation model (DEM), slope, aspect and proximity to roads and settlements, factors that influ- ence the behavior of fire, were used to model the forest fire risk zones. Each class of the layers was given weight according to their fire inducing capability and their sensitivity to fire. Weighted sum modeling and ISODATA clustering was used to classify the fire zones. To validate the results, Along Track Scanning Radiometer (ATSR), the historical fire hotspots data was used to check the occurrence points and modeled forest fire locations. The forest risk zone map has 55 63% of agreement with ATSR dataset.     

METHODS OF EVALUATING FOREST FIRE HISTORY

Forest fire history can be reconstructed over past centuries across a widevariety of forest types.Fire scars on living tress,and age classes of forest stands,are thetwo sources of information for these reconstructions.Point and area frequencies are usedto reconstruct fire history.Point frequencies are useful in forest types that burn withfrequent,low intensity fire so that many fire-scarred residual trees exist.A true point isa single tree,but more often point estimates are made by combining fire scar records fromseveral adjacent trees.Area frequences are applied where fires are infrequent but ofmoderate to high intensity,so that stand ages are used across wide areas to estimate firereturn interals.Proper selection and application of fire history methods are essential toderiving useful ecological implications from fire history studies.This review evaluates the common methods of determining fire history:what thetechniques are,where they are best applied,and how to interpret them in an ecologicalcontext.E     

林火生态因子的时空动态

本文从林分的时空角度入手 ,着重分析了不同林分、林龄、郁闭度随时间的推移导致森林火灾危险性的变化 ,其一般规律是 :中郁闭度林分 ,年龄增加、郁闭度增加 ,林木枝下高增加快 ,从而地表火发生率降低 ,树冠火危险性增大 ;长期未郁闭的疏林 ,地表火危险长期存在 ,林分生产力低 ;灌木、草坡是地表火发生率最高 ,生产力最低的类型。所以 ,根据不同分区林分特点 ,提出了合理的营林防火措施     

Effects of fire disturbance on bird communities and species of mountain Serrano forest in central Argentina

In central Argentina, Serrano forest has a long history of fire disturbance; however, the impact of fire on avifauna remains unknown. We compared the avian–habitat relationships in forest patches with low, moderate, and high fire regimes using a community-level (species richness, abundance, ordination and guilds) and species-level (indicator species analysis) approach. In patches under each fire condition, we recorded bird community composition, richness and abundance, and different vegetation structure variables. The site under high-severity fire regime was structurally poor and had been converted from original forest to dense grassland. There, diversity of bird community was low, retaining approximately 30 % of the species present in the least impacted site. Avian assemblage was dominated by generalist and open area birds. Guilds were underrepresented, showing an important reduction of foliage granivorous, nectarivorous, omnivores, and foliage and bark insectivorous, and absence of fly-catchers. Moreover, low abundance of forest understory, midstory, and canopy species and of birds belonging to open and closed nesting guilds was detected. By contrast, under low and moderate-severity fire regimes highest bird diversity as well as highest representativeness of most guilds was observed. Forest bird species were strongly associated with low fire disturbance, whereas moderate fire disturbance was characterized by the presence of forest and generalist species. Given the critical conservation status of Serrano forest in Córdoba, Argentina, habitat restoration and protection of forest relicts could be suitable measures to promote avifauna preservation.     

GIS-based forest fire susceptibility mapping in Iran: a comparison between evidential belief function and binary logistic regression models

The aim of this research was to produce forest fire susceptibility maps (FFSM) based on evidential belief function (EBF) and binary logistic regression (BLR) models in the Minudasht Forests, Golestan Province, Iran. At first, 151 forest fire locations were identified from Moderate-Resolution Imaging Spectero Radiometer data, extensive field surveys, and some reports (collected in year 2010). Out of these locations, 106 (70%) were randomly selected as training data and the remaining 45 (30%) cases were used for the validation goals. In the next step, 15 effective factors such as slope degree, slope aspect, elevation, plan curvature, Topographic Position Index, Topographic Wetness Index, land use, Normalized Difference Vegetation Index, distance to villages, distance to roads, distance to rivers, wind effect, soil texture, annual temperature, and rainfall were extracted from the spatial database. Subsequently, FFSM were prepared using EBF and BLR models, and the results were plotted in ArcGIS. Finally, the receiver operating characteristic curves and area under the curves (AUCs) were constructed for verification purposes. The validation of results showed that the AUC for EBF and BLR models are 0.8193 (81.93%) and 0.7430 (74.30%), respectively. In general, the mentioned results can be applied for land use planning, management and prevention of future fire hazards.     

Characterization of forest fires in Catalonia (north-east Spain)

The present study analyses the temporal variation in the distribution of the number of fires, area burned and fire sizes in Catalonia using fire data from 1942 to 2002. The study shows variations in the distribution of fire size over recent decades, with a significant increase in the number of very large fires. The study also analyses relationships between characteristics of the forest (altitude, slope, aspect, living fuels and species composition) and the probability of the fire occurrence. The analysis is based on the overlay of forest cover data and perimeters of forest fires during the period (1986–2002). Of the analysed variables, altitude affects most the probability of fire occurrence, with higher proportions of burned forest area at lower altitudes. Stand’s vertical structure is also relevant, with lower proportions of burned area in stands with mature tree cover without understory. The study helps to analyse the strengths and weaknesses of forest and fire management policies, especially those related to forest and fuel management at the landscape level.     

基于RS和GIS的云南省森林火险预报研究

基于遥感、GIS技术,选取不同植被易燃等级、植被干燥度、森林气象火险预报等级作为森林火险预报因子,采用因子加权叠置法,计算得到云南省森林火险预报指数,划分为没有危险、低度危险、中度危险、高度危险和极度危险5个等级。研究结果表明,较之传统的森林火险气象预报,该预报模型能够更为准确地预测林火发生的可能性,更好地满足森林防火业务的需求。     

Evaluation of the growth function of an empirical forest scenario model

Forests have an important role in the global carbon cycle as carbon pools, sinks and sources, and their quantification has become a relevant task. Empirical models based on national forest inventories are widely used for the assessment of carbon sequestration. However, these models do not treat explicitly all the processes occurring in the ecosystem, as they are mainly based on statistical relations to estimate forest development. Therefore, there is a need for validation of these models to increase confidence in the predictions of future forest development. This study evaluates an empirical single-tree model that was developed in Switzerland (MASSIMO). The accuracy and precision of the growth function of the model is evaluated with data from the National Forest Inventory (NFI) of Liechtenstein. MASSIMO was found to predict the basal area per hectare of the Liechtenstein data very precisely (underestimation of 0.65%). The main differences between observed and predicted diameter increment occur mostly for larger DBH classes, where the increment is underestimated by the model. However, these differences may be related to the precision of the input variables. For example, the explanatory variable stand age is determined with relatively low precision; therefore it shows a high variability. For future model development, either the variable stand age should be estimated more reliably, or stand age should not be an explanatory variable of the growth function.     

Estimating natural forest fire return interval in northeastern Ontario,Canada

Long-term forest fire regime was simulated for the Moose River Forest Management Unit (FMU) in northeastern Ontario. The simulated area has not been managed for timber production and fire suppression activity has been minimal. The available data included fire records for 1970–2006 and forest age structure from forest resource inventory completed in 1978. The fire regime was simulated using a simple percolation model driven by three parameters: probabilities of fire spread during low and high fire activity years and of a given year being a low fire activity year. The model successfully generated a long-term fire regime producing age structure and 37-year-long fire records similar to those observed for the Moose River FMU. The simulation results suggest that (a) fire return interval in northeastern Ontario is likely much shorter than indicated by estimates based exclusively on data from the last four decades of fire activity, and (b) it is possible that the fire regime in northeastern Ontario has not changed since mid-1800s but rather is characterized by relatively long periods of low incidence of fire interspersed with pulses of high fire activity.