湖北省宜昌市森林防火瞭望塔通视性评价研究

通视性评价是G IS可视化的重要内容,在森林防火、建筑规划、景观分析等领域具有重要作用和广泛的应用前景。以宜昌市14个代表性的森林防火瞭望塔为研究对象,进行通视性分析,结果表明:①通视性受瞭望塔的高度、可视距离等因素限制,也与地形有很大关系;精度取决于空间数据和配套属性数据的准确性,与DEM建模中使用的插值方法有关。②宜昌市森林防火瞭望塔可视距离按10km计算,14个瞭望塔可视区域面积占市总面积的12.1%;防火瞭望塔可视距离按理想可视距离(无阻挡无限可视),则14个瞭望塔可视区域面积占市总面积的68.32%。③通视性分析可为宜昌市后期瞭望塔布点提供参考,并在图上实现先期可视化。     

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.     

Pinus pinaster Ait. tree mortality following wildfire in Spain

Maritime pine (Pinus pinaster Ait.) is the tree species most affected by wildfire in the Iberian Peninsula. Prediction of the probability of fire-injured tree mortality is critical for management of burned areas, evaluation of the ecological and economic impact of wildfire and prescribed fire planning and application. Pine bark beetles (Scolytidae) frequently attack burned maritime pine stands and cause extensive post-fire mortality throughout the Iberian Peninsula. In the present study, maritime pine trees were monitored for three years following 14 wildfires in four ecotypes in Spain (11 fires in Galicia (Galician ecotype - NW Spain), one fire in Portillo (Meseta-Castellana ecotype - Central Spain), one fire in Rodenal (Rodenal ecotype - Central Spain), and one fire in Genalguacil (Sierra Bermeja ecotype - SW Spain)). Data on tree attributes, crown and bole injury, ground fire severity, Ips sp. presence and tree survival were obtained by examining 3085 trees. Logistic regression models for predicting the probability of delayed maritime pine mortality were developed by use of generalized estimated equations (GEE). An ample range of response to fire damage in mortality was evident among the four ecotypes and different models were fitted for each. The most important variables for predicting tree mortality were total crown volume damaged, presence of Ips sp. attack and cambium kill rating. The results highlight the extensive presence of Ips sp. in burned maritime pine forests and its importance in tree mortality process, the ample range of response of P. pinaster, in terms of post-fire mortality, as well as the need to develop site specific mortality models for the different ecotypes of this species following fire.     

The European Forest Fire Information System in the context of environmental policies of the European Union

Since the mid-20th century, countries in Europe have been organized to record information on forest fires and their effects. These initiatives were established at regional and often national level, without major interaction among countries in Europe. With the expansion of the European Union in the 1980s, when Mediterranean countries were incorporated in the EU, the issue of forest fires increased in relevance, mainly due to the damages caused by fires in the natural areas of these countries. Initial EU policies related to fires date back to the 1980s, in which the European Union elaborated the first voluntary Regulations to support the development of forest fire information systems in the countries. Although EU environmental policies promoted the development of national systems, the first steps towards the development of a European fire information system did not take place until the late 1990s. Such a system was initially discussed between the European Commission services and the Member States in 1998. Although the development of the European Forest Fire Information System (EFFIS) started at this time, its official establishment came only in place with the publication of the Forest Focus regulation in 2003, which included within its implementation rules the reference to EFFIS. Since its establishment, EFFIS has influenced the further development of EU environmental policies on forest protection. It has further shaped the link of these to other forest and regional policies, which, although not fire-specific, did address the issue of damages caused by fires to the European environment and its population. The present article describes the steps in the development of the EU fire policies and EFFIS. It provides a synoptic view of how fires are included in different sectoral policies of the EU, and suggests ways in which the continuation of forest fire monitoring and management may be included in future European policies.     

Long-term forest management after wildfire(Catalonia,NE Iberian Peninsula)

Studies of post-fire soil status in Mediterranean ecosystems are common;however,few have examined the effects of long-term forest management after a wildfire on physicochemical soil properties.Here,we analyzed differences in soil properties attributable to long-term postfire management and assessed the sustainability of these management practices in relation to the soil properties.The study area is located in Odena in the northeast region of the Iberian Peninsula consisted of the control forest(burned more than 30 years ago),low density forest(LD;burned in a wildfire in 1986 and managed in 2005)and high density forest(HD;burned in a wildfire in 1986 and no managed).For soils from each plot,we measured soil water repellency,aggregate stability,total nitrogen(TN),soil organic matter(SOM),inorganic carbon(IC),pH,electrical conductivity,extractable calcium,magnesium,sodium,potassium(K),phosphorus,aluminum(Al),manganese(Mn),iron(Fe),zinc,copper,boron,chrome,silicon and sulfur and calculated the ratios of C/N,Ca+Mg/(Na+K)^1/2,Ca/Al and Ca/Mg.Significant differences were found in TN,IC,SOM,pH,K,Al,Mn,Fe and C/N ratio(p<0.05).All soil properties were found to have largely recovered their pre-fire values.Soils were affected by the post-fire management practices implemented 20 years after the fire,as reflected in their respective physicochemical properties,so that soil properties at the control and LD sites are more similar today than those at the control and HD sites.Thus,sustainable forest management can overcome soil degradation in areas affected by wildfire in the medium-and long-term by improving soil properties.     

Multi-attribute evaluation of landscape-level fuel management to reduce wildfire risk

This paper provides an example of the practical application of multi-attribute trade-off analysis (MATA) to wildfire management. The MATA approach supports more informed decision-making because it exposes important trade-offs among competing management objectives (requiring value-based choices), helps guide and structure necessary technical judgements, explicitly represents uncertainty (i.e., not just expected outcomes but risk profiles around outcomes) and addresses temporal trade-offs. MATA promotes critical thinking about what analysis is required for decision-making. A MATA approach can be applied for all types of forest and fire management decisions. In this paper, we provide a sample application of MATA to an evaluation of landscape-level fuel treatments for managing wildfire risk. The study area is located in southeastern British Columbia, Canada where historical fire suppression policies and expanding development in wildland urban interface areas have resulted in an increase in both the probability and the consequences of stand replacement fires. We specify management objectives and develop measurable attributes for fire management costs, timber supply, property damage, landscape-level biodiversity, local air quality and climate change. We then simulate the effects on these attributes of four alternative fuel management strategies that include combinations of mechanical treatments and prescribed burning over a 100-year period. The evaluation illustrates the key features of MATA while highlighting the benefits and challenges of implementing the approach.     

Fire history of white and Lutz spruce forests on the Kenai Peninsula,Alaska, over the last two millennia as determined from soil charcoal

The presence of over 429,000 ha of forest with spruce (Picea spp.) recently killed by spruce beetles (Dendroctonus rufipennis) on the Kenai Peninsula has raised the specter of catastrophic wildfire. Dendrochronological evidence indicated that spruce beetle outbreaks occurred on average every 50 years in these forests. We used 121 radiocarbon-dated soil charcoal samples collected from throw mounds of recently blown over trees to reconstruct the regional fire history for the last ca. 2500 years and found no relation between fire activity and past spruce beetle outbreaks. Soil charcoal data suggest that upland forests of white (Picea glauca) and Lutz (Picea x lutzii) spruce have not on average burned for 600 years (time-since-fire range 90 to ∼1500 years, at 22 sites) and that the mean fire interval was 400–600 years. It would thus appear that 10 or more spruce beetle outbreaks can occur for every cycle of fire in these forests. We caution, however, that a trend of warmer summers coupled with an increasing human population and associated sources of ignitions may create a greater fire risk in all fuel types than was present during the time period covered by our study. We suggest that forest management focus on creating fuel breaks between valued human infrastructure and all types of forest fuels, both green and dead.     

Are drought and wildfires turning Mediterranean cork oak forests into persistent shrublands?

In the Iberian Peninsula Mediterranean oak forests have been transformed into a mosaic landscape of four main patch-types: forests, savannas, shrublands and grasslands. We used aerial photographs over a period of 45 years (1958–2002) to quantify the persistence and rates of transitions between vegetation patch-types in southern Portugal, where cork oak is the dominant tree species. We used logistic regression to relate vegetation changes with topographical features and wildfire history. Over the 45 years, shrublands have been the most persistent patch-type (59%), and have been expanding; forests are also persistent (55%) but have been decreasing since 1985; savannas and grasslands were less persistent (33% and 15%, respectively). Shrublands persistence was significantly correlated with wildfire occurrence, particularly on southern exposures after 1995. In contrast, forest persistence decreased with wildfire occurrence, and forests were more likely to change into shrublands where wildfire had occurred after 1995.     

Regional patterns of fire recurrence effects on calcareous soils of Mediterranean Pinus halepensis communities

The effects of fire recurrence on soils were studied on calcareous sites of Mediterranean Pinus halepensis-dominated communities in Catalonia (NE Iberian Peninsula). Soil organic horizons and mineral soils of 15 sites consisting in two adjacent areas, one burnt only once (in 1994) and the other burnt twice (in the same 1994 fire but also once before, from 1975 to 1993) were surveyed 9 years after the last fire. Fire recurrence decreased the occurrence and dry mass of soil organic horizons. Total nitrogen concentration in L organic horizon was higher in less recurrently burnt areas. No other significant difference between once- and twice-burnt areas was found for any studied chemical parameter either in organic L and FH horizons or in mineral soils. The present study underlines the fact that fire effects on soil organic horizons are accumulated through consecutive fires.     

Chapter 13. Methodology for Determining Wildfire and Prescribed Fire Air Quality Impacts on Areas in the Western United States

Summary

Colorado has long been known for its scenic vistas and majestic mountains. Wildfires which are common in the summer months can significantly impact scenic environments close to the wildfire location. There are also concern as to the health impact to people in towns and cities located on the urban/wildland interfaces where the impact can also include loss of life and property. For these and other reasons, a concerted effort is underway to better understand the implications of these wildfires on areas potentially impacted by smoke.

This study created a methodology for evaluating air quality impacts on both a statewide and regional basis using a state-of-the-art meso-scale meteorological model to simulate the meteorological conditions which correlate with prescribed fire and wildfire activity. These meteorological fields are input into an air quality model which simulates transport and secondary aerosol formation for certain pollutants. This modeling effort makes use of climatological analyses derived from observational data provided by the Grand Canyon Visibility Transport Commission (GCVTC). Locally, the model examines impacts within the urban/wildland interface to the extent possible. The regional analysis evaluates the impact of long range transport on neighboring states and the relative impacts on states downwind from areas with the potential for extreme wildfire events.     

Wildfires,responsibility and trust: public understanding of Sweden's largest wildfire

Wildfires present a growing risk to many countries, and climate change is likely to exacerbate this risk. This study analyzes how people directly affected by a wildfire understand its causes and consequences, as well as the future risk of wildfires. The point of departure is that social understanding of wildfires has an important influence on the consequences that emerge in the wake of a wildfire. The empirical case analyzed here is the largest forest fire in modern Swedish history, and the material basis of the study is a postal survey to all individuals directly affected by the fire. The results revealed a complex picture of the respondents’ understanding of the wildfire. Even if the fire was human caused, there was little blame toward forest companies and fire departments. Many positive consequences, such as a long-term increase in biodiversity, were attached to the disaster, and there was a belief that organizations will learn from it and take action to limit wildfires in the future. Simultaneously, the majority of the respondents believed that climate change may lead to an increased risk of forest fires in the future. These findings illustrate the complexity of people's perceptions of the fire and its aftermath.     

The cost of stress resistance: construction and maintenance costs of leaves and roots in two populations of Quercus ilex

We tested whether growth and maintenance costs of plant organs vary with environmental stress. Quercus ilex L. seedlings from acorns collected from natural populations in the northern Iberian Peninsula and in a lower elevation and putatively less stressful habitat in the southern Iberian Peninsula were grown in pots under the same conditions. Growth and maintenance respiration were measured by CO(2) exchange. Young leaves from 5-month-old seedlings of both populations had similar mean specific leaf areas, nitrogen and carbon concentrations and specific growth rates, and almost identical growth costs (1.26 g glucose g(-1)). Leaf maintenance cost was higher in northern than in the southern population (27.3 versus 22.4 mg glucose g(-1) day(-1), P < 0.01). In both populations, leaf maintenance cost decreased by 90% as leaves aged, but even in mature leaves, the maintenance cost was higher in the northern population than in the southern population (3.38 versus 2.53 mg glucose g(-1) day(-1), P < 0.01). The growth costs of fine roots < 1 mm in diameter were similar in the two populations (1.20 g glucose g(-1)), whereas fine root maintenance cost was higher in the northern population than in the southern population (9.86 versus 7.45 mg glucose g(-1) day(-1); P < 0.05). The results suggest that the cost of organ maintenance is related to the severity of environmental stress in the native habitat. Because the observed differences in both leaves and roots were constitutive, the two populations may be considered ecotypes.     

Wildfire risk in the wildland–urban interface: A simulation study in northwestern Wisconsin

The rapid growth of housing in and near the wildland–urban interface (WUI) increases wildfire risk to lives and structures. To reduce fire risk, it is necessary to identify WUI housing areas that are more susceptible to wildfire. This is challenging, because wildfire patterns depend on fire behavior and spread, which in turn depend on ignition locations, weather conditions, the spatial arrangement of fuels, and topography. The goal of our study was to assess wildfire risk to a 60,000 ha WUI area in northwestern Wisconsin while accounting for all of these factors. We conducted 6000 simulations with two dynamic fire models: Fire Area Simulator (FARSITE) and Minimum Travel Time (MTT) in order to map the spatial pattern of burn probabilities. Simulations were run under normal and extreme weather conditions to assess the effect of weather on fire spread, burn probability, and risk to structures. The resulting burn probability maps were intersected with maps of structure locations and land cover types. The simulations revealed clear hotspots of wildfire activity and a large range of wildfire risk to structures in the study area. As expected, the extreme weather conditions yielded higher burn probabilities over the entire landscape, as well as to different land cover classes and individual structures. Moreover, the spatial pattern of risk was significantly different between extreme and normal weather conditions. The results highlight the fact that extreme weather conditions not only produce higher fire risk than normal weather conditions, but also change the fine-scale locations of high risk areas in the landscape, which is of great importance for fire management in WUI areas. In addition, the choice of weather data may limit the potential for comparisons of risk maps for different areas and for extrapolating risk maps to future scenarios where weather conditions are unknown. Our approach to modeling wildfire risk to structures can aid fire risk reduction management activities by identifying areas with elevated wildfire risk and those most vulnerable under extreme weather conditions.     

Pathways for resilience in Mediterranean cork oak land use systems

Context

Loss of woodlands and degradation of vegetation and soil have been described for all Mediterranean-type ecosystems worldwide. In the Western Iberian Peninsula, overexploitation of evergreen cork oak land use systems has led to soil erosion, failures in oak recruitment, and loss of forests. Degraded and dry sites are quickly colonised by pioneer heathland rockrose (Cistus spp.) shrubs forming highly persistent patches.

Aims

Although traditionally shrublands have been considered as a transient successional state, we present evidence that they can represent persistent alternative states to former cork oak forests.

Review trends and conclusions

We first describe how Mediterranean vegetation evolved in the Iberian Peninsula and the role of fire and long-term human management as main disturbances. We then discuss alternative pathways through state-and-transition models indicating the ecological and land use variables that halt cork oak regeneration and recruitment and drive vegetation transitions towards persistent shrublands. Unless concerted management actions and restoration programmes are undertaken, the cork oak land use systems will not be sustainable.     

Eight years of seasonal burning and herbicidal brush control influence sapling longleaf pine growth,understory vegetation,and the outcome of an ensuing wildfire

To study how fire or herbicide use influences longleaf pine (Pinus palustris Mill.) overstory and understory vegetation, five treatments were initiated in a 5–6-year-old longleaf pine stand: check, biennial arborescent plant control by directed herbicide application, and biennial burning in March, May, or July. The herbicide or prescribed fire treatments were applied in 1999, 2001, 2003, and 2005. All prescribed fires were intense and averaged 700 kJ/s/m of fire front across all 12 burns. Using pretreatment variables as covariates, longleaf pine survival and volume per hectare were significantly less on the three prescribed fire treatments than on checks. Least-square means in 2006 for survival were 70, 65, 64, 58, and 56% and volume per hectare was 129, 125, 65, 84, and 80 m³/ha on the check, herbicide, March-, May-, and July-burn treatments, respectively. A wildfire in March 2007 disproportionately killed pine trees on the study plots. In October 2007, pine volume per hectare was 85, 111, 68, 98, and 93 m³/ha and survival was 32, 41, 53, 57, and 55% on the check, herbicide, March-, May-, and July-burn treatments, respectively, after dropping trees that died through January 2009 from the database. Understory plant cover was also affected by treatment and the ensuing wildfire. In September 2006, herbaceous plant cover averaged 4% on the two unburned treatments and 42% on the three prescribed fire treatments. Seven months after the wildfire, herbaceous plant cover averaged 42% on the two previously unburned treatments and 50% on the three prescribed fire treatments. Before the wildfire, understory tree cover was significantly greater on checks (15%) than on the other four treatments (1.3%), but understory tree cover was similar across all five treatments 7 months after the wildfire averaging 1.1%. The greater apparent intensity of the wildfire on the previously unburned treatments most likely resulted from a greater accumulation of fuels on the check and herbicide plots that also collectively had a higher caloric content than fuels on the biennially prescribed burned plots. These results showed the destructive force of wildfire to overstory trees in unburned longleaf pine stands while also demonstrating the rejuvenating effects of wildfire within herbaceous plant communities. They caution for careful reintroduction of prescribed fire even if fire was excluded for less than a decade.     

Expansion of the aphid Myzocallis (Lineomyzocallis) walshii (Monell) on the red oak Quercus rubra, and adaptation of local parasitoids in the northeastern Iberian Peninsula (Hom., Aphididae, Calaphidinae; Hym., Braconidae, Aphidiinae)

An ongoing expansion of Myzocallis (L.) walshii (Monell) in the NE Iberian Peninsula was detected. The aphid species was recorded in Catalonia, Andorra and Navarra. Adaptation of local native parasitoids (at least Trioxys pallidus Haliday and T. tenuicaudus Stary) to the new immigrant was documented, together with background information on their host range in the native environments. The detection of parasitoids of M. walshii is the first published evidence in Europe. The new evidence for M. walshii in the NE Iberian Peninsula also supports the warning of the expansion of the aphid as a pest of Quercus rubra over Europe.     

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.     

Effects of fuel treatments on carbon-disturbance relationships in forests of the northern Rocky Mountains

Fuel treatments alter conditions in forested stands at the time of the treatment and subsequently. Fuel treatments reduce on-site carbon and also change the fire potential and expected outcome of future wildfires, including their carbon emissions. We simulated effects of fuel treatments on 140 stands representing seven major habitat type groups of the northern Rocky Mountains using the Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS). Changes in forest carbon due to mechanical fuel treatment (thinning from below to reduce ladder fuels) and prescribed fire were explored, as well as changes in expected fire behavior and effects of subsequent wildfire. Results indicated that fuel treatments decreased fire severity and crown fire occurrence and reduced subsequent wildfire emissions, but did not increase post-wildfire carbon stored on-site. Conversely, untreated stands had greater wildfire emissions but stored more carbon.     

森林火险天气等级预报与应用

详细介绍了森林火险天气预报等级指数,结合兴隆林业局的实际情况,阐述了森林火险天气等级预报在了望、巡护及灭火准备中的应用对策。     

Variation in fire interval sequences has minimal effects on species richness and composition in fire-prone landscapes of south-west Western Australia

Prescribed burning is used in many fire-prone ecosystems for wildfire mitigation and conservation of biodiversity. However, there is limited information about how biota responds to long-term fire management, especially at a whole-of-community level. We studied community responses to different fire interval sequences resulting from planned and unplanned fires in Mediterranean-climate ecosystems in the Warren bioregion of south-west Western Australia (SWA) to determine the resilience of the biota to contrasting fire regimes. Fire history data were used to identify contrasting fire interval sequences in forest and shrubland communities for the period 1972-2004. We surveyed vascular plants, ants, beetles, vertebrates and macrofungi at 30 sites to investigate community-level responses to consecutive short (SS: ≤5 years), consecutive long (LL: ≥10 years), one very long (VL: 30 years), or mixed/moderate (M: 6-9 years) fire interval(s). All sites had a common time-since-fire of ∼4 years at the commencement of sampling which was conducted over two years. Species richness and composition differed between forest and shrubland communities, but the influence of fire interval sequences on taxonomic groups was minimal and difficult to detect. There was weak evidence of compositional differences between SS and LL/VL regimes for plants, ants, beetles and macrofungi but no difference between these regimes and the intermediate disturbance M-regime. These results demonstrate the resilience of the biota in open forests and shrublands of SWA to contrasting fire interval sequences over the past 30 years. We conclude that occasional short (3-5 years) intervals between fires are unlikely to have a persistent effect on community composition, though maintaining a regime of short or long intervals may alter species composition and/or abundance. We suggest that variability in fire intervals is important for long-term conservation of the biota. For the Warren Region, prescribed burning at an intermediate level of disturbance and incorporating variability in interval length is recommended to achieve the dual objectives of wildfire mitigation and biodiversity conservation.