Forest fire effects in beech dominated mountain forest of Iran

Most of world's forests of different climates have a history of fire, but with different severities. Fire regimes for broadleaf deciduous forests have return intervals that vary from many decades (or less) to centuries (or more). Iran has a total of 1.2 million ha of temperate forest in the north, where fires burn about 300–400 ha annually. This study focused on the impact of fire on forest structure, tree species quality, and regeneration composition (specially beech) in the Chelir forest of northern Iran. The results showed that forest fires changed the structure and had different effects on tree species composition between burned and control areas. Thin barked species such as oriental beech (Fagus orientalis Lipsky) and coliseum maple (Acer cappadocicum Gled.) have been affected more than those with thick bark, like hornbeam (Carpinus betulus L.) and chestnut-leaved oak (Quercus castaneifolia C.A. Mey). The density of oriental beech regeneration in the unburned area was greater than in the burned area, while the quantity of regeneration of hornbeam, coliseum maple and velvet maple (Acer velutinum Boiss) was higher in burned area. Forest fire had a greater effect on oriental beech quality, and changed regeneration composition in the burned area. Fire prevention activities should be considered as a silvicultural treatment for preserving these valuable forests.     

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.     

Bird communities following high-severity fire: Response to single and repeat fires in a mixed-evergreen forest,Oregon, USA

Fire is a widespread natural disturbance agent in most conifer-dominated forests. In light of climate change and the effects of fire exclusion, single and repeated high-severity (stand-replacement) fires have become prominent land management issues. We studied bird communities using point counting in the Klamath-Siskiyou ecoregion of Oregon, USA at various points in time after one or two high-severity fires. Time points included 2 and 3 years after a single fire, 17 and 18 years after a single fire, 2 and 3 years after a repeat fire (15 year interval between fires), and >100 years since stand-replacement fire (mature/old-growth forest). Avian species richness did not differ significantly among habitats. Bird density was highest 17 and 18 years after fire, lowest 2 years after fire, and intermediate in repeat burns and unburned forest. Bird community composition varied significantly with habitat type (A = 0.24, P < 0.0001) with two distinct gradients in species composition relating to tree structure (live to dead) and shrub stature. Using indicator species analysis, repeat burns were characterized by shrub-nesting and ground-foraging bird species while unburned mature forests were characterized by conifer-nesting and foliage-gleaning species. Bird density was not related to snag basal area but was positively related to shrub height. Contrary to expectations, repeated high-severity fire did not reduce species richness, and bird densities were greater in repeat burns than in once-burned habitats. Broad-leaved hardwoods and shrubs appear to play a major role in structuring avian communities in the Klamath-Siskiyou region. In light of these results, extended periods of early seral broadleaf dominance and short-interval high-severity fires may be important to the conservation of avian biodiversity.     

Breeding bird community composition in different successional vegetation in the montane coniferous forests zone of Taiwan

To examine the relationship between forest succession following fire and the composition of bird communities, we investigated the vegetation structure, bird population density, foraging behavior and guild structure in bamboo grasslands (11 years since the last fire), pine savanna (41 years), pine woodland (58 years), old-growth hemlock forest (never burned), and old-growth spruce forest (never burned) in the Tatachia area of central Taiwan. Canopy height, total foliage cover, tree density, total basal area of tree, total basal area of snags, foliage height diversity, and tree species richness all increased with successional age. However, shrub cover peaked in intermediate successional stages. The vertical profile of foliage cover was more diverse in later successional forests, which had more breeding bird species and ecological guilds. All the breeding bird species recorded in early and intermediate stages were also found distributed in the late successional forests. Because Taiwan has high precipitation and humidity, and most forest fires in Taiwan are caused by human activities, forest fires and large areas of early successional vegetation were probably rare in the mountain areas of Taiwan prior to the arrival of humans. Therefore, bird species have not had enough time to adapt to areas with early or intermediate successional vegetation. Moreover, late successional forests host all the major plant species found in the early and intermediate stages and have higher foliage height diversity index, which was positively correlated with the bird species richness and bird species diversity index in this study. As a result, all breeding bird species and guilds in the area can be found in late successional forests. Efforts for conserving avian diversity in Taiwan should focus on protecting the remaining native old-growth forests.     

Land cover analysis in wildland-urban interfaces according to wildfire risk: A case study in the South of France

Each year, forest fires destroy about 500,000 ha of vegetation in Europe, predominantly in the Mediterranean region. Many large fires are linked to the land transformations that have taken place in the Mediterranean region in recent decades that have increased the risk of forest fires. On the one hand, agricultural fallows and orchards are slowly being colonized by vegetation, and on the other hand, the forest is not sufficiently used, both of which result in increased accumulation of fuel. In addition, urbanization combined with forest extension results in new spatial configurations called “wildland-urban interfaces” (WUI). WUI are commonly defined as “areas where urban areas meet and interact with rural lands, wildland vegetation and forests”. Spatial analyses were performed using a WUI typology based on two intertwined elements, the spatial organization of homes and the structure of fuel vegetation. The organization of the land cover in terms of representativeness, complexity or road density was evaluated for each type of WUI. Results showed that there were significant differences between the types of WUI in the study area. Three indicators (i) “fire ignition density”, derived from the distribution of fire ignition points, (ii) “wildfire density”, derived from the distribution of wildfire area and (iii) “burned area ratio”, derived from the proportion of the burned area to the total study area were then compared with each type of WUI. Assuming that the three indicators correspond to important aspects of fire risk, we showed that, at least in the south of France, WUI are at high risk of wildfire, and that of the different types of wildland-urban interfaces, isolated and scattered WUI were the most at risk. Their main land cover characteristics, i.e. low housing and road densities but a high density of country roads, and the availability of burnable vegetation such as forested stands and shrubland (garrigue) explain the high fire risk. Improving our knowledge of relationships between WUI environments and fire risk should increase the efficiency of wildfire prevention: to this end, suitable prevention actions and communication campaigns targeting the types of WUI at the highest risk are recommended.     

Long term effects of fire on ectomycorrhizas and soil properties in Nothofagus pumilio forests in Argentina

The forests of Nothofagus pumilio have historically been affected by forest fires. The effects of fire on certain above and belowground, biotic and abiotic components of these ecosystems have been previously documented, albeit belowground components have received much less attention. It has been suggested that the effects observed in the short-term after a fire usually differ from the longer-term effects. The long-term effects of fire (i.e. >5 years after burning) on belowground components in Nothofagus forests are currently unknown. In the present study we evaluated the long-term effect of fire on ectomycorrhiza (ECM) colonization and morphotype composition in N. pumilio roots, as well as soil chemical properties in temperate forests in Patagonia. Sampling was conducted in three mature monospecific forests. In each, nearby burned and unburned sites were selected. The time since the occurrence of fires differed between areas (i.e. 6-10 years). Within each site, 3 transects of 40 m were established randomly along which 5 samples of roots and soil were collected in spring and autumn. The main results were: (1) in comparison with the unburned site, ECM colonization was lower in the burned site in the area with the shorter time length since fire occurrence and no effects in the other two areas were observed; (2) richness and diversity were not significantly affected by fire but there was a significant effect of season for both parameters, being higher in spring; (3) ECM dominance was significantly higher in the unburned than in the burned site in Tronador, while in Challhuaco the opposite was observed, mainly in autumn; (4) in general carbon, nitrogen and phosphorous decreased while pH increased in the burned sites; (5) ECM colonization positively correlated with NH⁴⁺ and phosphorus and negatively with pH but was not significantly correlated with organic matter or any other soil variable. Altogether the results suggest that effects of fire on ectomycorrhiza and soil properties in N. pumilio forests are probably related to the time elapsed since fire occurrence combined with site characteristics. In addition, the direct and indirect effects of fire in these forest systems may persist for more than 10 years.     

Woodland salamander response to two prescribed fires in the central Appalachians

Using coverboard arrays, we monitored woodland salamanders on the Fernow Experimental Forest in the central Appalachian Mountains, West Virginia, USA prior to and following two prescribed fires in mixed oak (Quercus spp.) forest stands. Treatments were burn plots on upper slopes or lower slopes fenced to prevent white-tailed deer (Odocoileus virginianus) herbivory or control plots that were unfenced and unburned. Most of the 7 species we observed were the mountain dusky salamander (Desmognathus ocropheaus), red-backed salamander (Plethodon cinereus) and slimy salamander (Plethodon glutinosis). Significant population responses were difficult to interpret with numerous treatment and year interactions. Results largely were equivocal. We found no change in woodland salamander assemblage prior to burning or afterwards. There were few differences in adult to juvenile ratios of salamanders among treatments. Still, a priori contrasts of mountain dusky salamanders and red-backed salamander counts corrected for detection probability were greater under coverboards in the 2 years monitored after both prescribed fires had occurred than before burning or in unburned controls. This suggests that these species responded to the reduced leaf litter on the forest floor by utilizing coverboards more. Similarly, the three predominate species of salamanders also were more numerous under coverboards in plots subjected to deer herbivory with less subsequent forest floor vegetation as compared to those burned plots that were fenced. Our observations would suggest that woodland salamanders somewhat are tolerant of two prescribed fires within close temporal proximity. However, because woodland salamanders can be significantly reduced following timber harvest, continued research is needed to fully understand impacts of fire as a pre-harvest management tool in central Appalachian forests.     

Clear cutting and burning affect nitrogen supply,phosphorus fractions and seedling growth in soils from a Wyoming lodgepole pine forest

Timber harvesting, with and without prescribed slash fire, and wild fire are common disturbances in pine forests of western North America. These disturbances can alter soil nitrogen (N) pools and N supply to colonizing vegetation, but their influence remains poorly understood for many forests. We investigated the effects of clear cut harvesting and fire on KCl extractable N pools, net N mineralization rates, phosphorus (P) fractions, seedling N uptake, and seedling growth in mineral soils sampled from a lodgepole pine forest in southern Wyoming. At a site where wild fire burned through a harvested stand of lodgepole pine and the adjacent intact forest, we analyzed mineral soils from the following four treatments: unburned clear cut, burnt clear cut, unburned forest, and burnt forest. Soils from unburned and burnt clear cut treatments had higher concentrations of KCl extractable N and higher net N mineralization rates, and produced larger pine seedlings in bioassays than soils from unburned and burnt intact forest treatments. Further, while seedlings grown in soils from the unburned and burnt forest treatments responded strongly to N fertilization, seedlings grown in clear-cut soils did not respond to fertilization. Taken together, these results suggest that harvesting had increased soil N supply. In comparing clear cut treatments, soils from the unburned clear cut had smaller extractable N and P pools, and lower net N mineralization rates, but produced larger pine seedlings than soils from the burnt clear cut.     

云南松林区的林火与火险等级分区初探

云南松林区发生的森林火灾是多种自然因素和人为活动综合作用的结果。通过对四川省云南松分布区不同区域与林火有关的主要气候因子分析及综合值的比较,结合地形地貌、植被状况和人为活动等多种因素,将我省云南松分布区划分成5个不同等级的火险区,并提出了相应的护林防火对策。     

火干扰对森林水文的影响

Fire is quite a common natural phenomenon closely related to forest hydrology in forest ecosystem. The influence of fire on water is indirectly manifested in that the post fire changes of vegetation, ground cover, soil and environment affect water cycle, water quality and aquatic lives. The effect varies depending upon fire severity and frequency. Light wildland fires or prescribed burnings do not affect hydrology regime significantly but frequent burnings or intense fires can cause changes in hydrology regime similar to that caused clear cutting.     

Estimation of gases emitted by forest fires based on remote sensing data

Forest fire, an important agent for change in many forest ecosystems, plays an important role in atmospheric chemical cycles and the carbon cycle. The primary emissions from forest fire, CO₂, CO, CH₄, long-chained hydrocarbons and volatile organic oxides, however, have not been well quantified. Quantifying the carbonaceous gas emissions of forest fires is a critical part to better understand the significance of forest fire in calculating carbon balance and forecasting climate change. This study uses images from Enhanced Thematic Mapper Plus (ETM+) on the Earth-observing satellite LANDSAT-7 for the year 2005 to estimate the total gases emitted by the 2006 Kanduhe forest fire in the Daxing’an Mountains. Our results suggest that the fire emitted approximately 149,187.66 t CO₂, 21,187.70 t CO, 1925.41 t C _x H _y , 470.76 t NO and 658.77 t SO₂. In addition, the gases emitted from larch forests were significantly higher than from both broadleaf-needle leaf mixed forests and broadleaf mixed forests.     

Long-term influence of fire and harvesting on boreal forest age structure and forest composition in eastern Québec

In boreal forests, historical variations in the area disturbed by natural disturbances or harvesting have rarely been compared. We measured temporal and spatial variations in areas affected by severe fires and clearcutting throughout the 20th century in a 57, 332 km² section of the eastern Canadian boreal forest. We examined the effects of these disturbances on spatio-temporal variations in the abundance of forests >60 years. Natural variability for the abundance of forests >60 years was estimated from simulations of natural disturbance regimes. We also measured compositional and structural differences between three categories of stands originating from relatively recent disturbances (∼50 years; clearcutting, fires, and clearcutting followed by fires), and one category of stands that were undisturbed for at least 200 years. At the regional level, we observed that forests >60 years gradually became scarcer throughout the 20th century due to a gradual expansion of harvested areas, an effect most pronounced in the southern part of the region, where mature and old forest abundance was clearly outside the range of natural variability at the end of the studied period. At the stand level, forest composition and structure differed between stand-origin categories: clearcutting-origin stands contained more balsam fir (Abies balsamea), fire-origin stands more black spruce (Picea mariana), and fire/clearcutting-origin stands more hardwoods (Betula papyrifera and Populus tremuloides). Overall, we estimate that strict forest management targets based on natural disturbance regimes will be difficult to achieve in eastern North-American boreal forests, most notably because contemporary disturbance rates, including both clearcutting and fire, have gradually become higher than the fire rates observed during the preindustrial period.     

Evaluating vegetation recovery following large-scale forest fires in Borneo and northeastern China using multi-temporal NOAA/AVHRR images

This study evaluated whether a normalized difference vegetation index (NDVI), derived from 8-km-resolution National Oceanic Atmospheric Administration (NOAA) Pathfinder AVHRR (advanced very high resolution radiometer) land (PAL) data, is appropriate for monitoring recovery following large-scale forest fires. Recovery processes were examined after fires on the island of Borneo and in northeastern China in 1983 and 1987, respectively. Based on pre- and post-fire NDVI differences (NDVId), six damage classes were established. Post-fire changes in land cover were monitored using (1) the average NDVI of all pixels corresponding to each damage class (A-NDVI) and (2) the ratio of a fire-affected A-NDVI to a non-fire-affected A-NDVI (QNDVI). Burn areas located by an NDVId threshold value were similar to reported burn areas. Both A-NDVI and QNDVI values signaled vegetation recovery, but the QNDVI gave much better results. For both the 1983 Borneo and 1987 northeastern China fires, QNDVI values dropped at the time of the fire and increased for about 4 years afterwards, although a 4-year period is obviously less than the time required for biomass recovery. Trends at the two study sites diverged after this period, however. The QNDVI values for multiple fire events in Borneo (in 1983, 1987, 1991, 1997, and 1998) showed that recovery times varied with the size of the burn area, but not with the damage class of the same event, whereas the severe-class QNDVI values for the fire in northeastern China in 1987 were still lower than the control value 10 years after the fire.     

Historic and current fire regimes in the Great Xing’an Mountains,northeastern China: Implications for long-term forest management

Understanding both historic and current fire regimes is indispensable to sustainable forest landscape management. In this paper, we use a spatially explicit landscape simulation model, LANDIS, to simulate historic and current fire regimes in the Great Xing’an Mountains, in northeastern China. We analyzed fire frequency, fire size, fire intensity, and spatial pattern of burnt patches. Our simulated results show that fire frequency under the current fire scenario is lower than under the historic fire scenario; total area burnt is larger with lower fire intensity under the historic fire scenario, and smaller with higher fire intensity under the current fire scenario. We also found most areas were burned by high intensity fires under the current fire scenario, but by low to moderate fires under the historic fire scenario. Burnt patches exhibit a different pattern between the two simulation scenarios. Large patches burnt by high intensity class fires dominate the landscape under the current fire scenario, and under historic fire scenario, patches burnt by low to moderate fire intensity fires have relatively larger size than those burnt by high intensity fires. Based on these simulated results, we suggest that prescribed burning or coarse woody debris reduction should be incorporated into forest management plans in this region, especially on north-facing slopes. Tree planting may be a better management option on these severely burned areas whereas prescribed burning after small area selective cutting, retaining dispersed seed trees, may be a sound forest management alternative in areas except for the severely burned patches.     

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.     

Fire history recorded on pine trunks and stumps: Influence of land use and fires on forest structure in North Karelia

Dendrochronological dating of fire scars was used to determine the history of forest fires, and the effects of the fires and of slash‐and‐burn cultivation on forest structure were studied in eastern Finland. A total of 67 fire years were dated over an area of 26 km². Forest fires increased towards the end of the 17th century and again towards the end of the 18th century, but decreased markedly in the middle of the 19th century. The mean fire interval was shorter near the historically known slash‐and‐burn cultivation areas than elsewhere. A forest survey map from 1913 was used to reconstruct the forest structure after the cessation of slash‐and‐burn cultivation and forest fires. This map showed that most of the younger forests were situated near old slash‐and‐burn cultivation areas, while the older forests were situated farther away from these. The proportion of deciduous trees decreased with increasing distance from slash‐and‐burn cultivation areas.     

Harnessing forest ecological sciences in the service of stewardship and sustainability: A perspective from ‘down-under’

Australia's native forests are predominantly Crown land, managed by the States. Regional Forest Agreements between four of the States and the Federal Government (1997–2001) resulted in a 36% increase in the area of conservation reserves and a 15% decrease in area of multiple-use (including timber harvesting) forests. The limited acceptance of timber harvesting in native forests, together with the rapid expansion of hardwood plantations, has diverted research focus away from native forests. Recent events including a prolonged drought and two forest fires totaling more than 3 million ha should have stimulated research in native forests on the effects of fire on ecosystem processes, on the management of fire and on management of water catchments; fires, far more than logging, are shaping our native forests in recent times. In particular, the use of prescribed fire to reduce fuels has decreased. We argue that Australian research effort in native eucalypt forests is lacking in two key areas – the effects of fire on carbon storage in forests and soils, and on the management of water yield from forested catchments. The results of forest research are variously published in the scientific journals, and increasingly in consultancy reports to governments or a to a range of organizations and industries. The question of who does the harnessing of knowledge coming from the science of forest ecology is compounded by constant changes in both political and management arrangements. If forest science is to assume a greater role in politics and forest management in Australia, scientists must enter the foray, using the fighting words of politics rather than maintaining the protective mantle of neutrality. With research in native forests being continually downgraded at both State and Federal levels, we take a somewhat less than optimistic view about how well ecological sciences will be harnessed in the service of forest stewardship and sustainability in Australia.     

National assessment of the evolution of forest fragmentation in Mexico

This paper presents assessments of the fragmentation of the temperate and tropical forests in Mexico at the national level for two dates 1993 and 2002. The study was based on land use and vegetation cover data sets scale 1:250,000. Two broad forest types (Temperate Forests and Tropical Forests) and five more specific forest types (Broadleaf Forests, and Coniferous Forests; Tropical Dry Deciduous Forests, Tropical Sub-evergreen Forests, and Tropical Evergreen Forests) were defined to conduct the analyses. FragStats 3.3 was used to estimate nine metrics of the spatial pattern of the forests for each forest type and date considered. The results indicate that the land cover transitions that have occurred between 1993 and 2002 have resulted in more isolated forest patches with simpler shapes in both the Temperate and Tropical Forests. The remaining Tropical Forest patches have become smaller and more numerous. In contrast, the remaining Temperate Forest patches are fewer and on average larger. Of the more specific forest types defined in this study, the Broadleaf Forests have the highest indicators of fragmentation. However these forests are usually embedded or adjacent to Coniferous Forests. Of more concern for conservation purposes are the high values of fragmentation metrics found for the Tropical Evergreen Forests and Tropical Dry Deciduous Forests, because these forest types are usually surrounded by non-forest land covers or anthropogenic land uses.     

管涔山森林植被与土壤类型的垂直分布规律

管涔山林区是山西省八大林区之一,位于吕梁山北端,山高坡陡,海拔高差及气候条件变化幅度大,植被和土壤垂直分布比较明显。为使该林区在森林经营管理中更加合理、科学,同时亦为专家研究提供依据,该文对管涔山东、西坡植被与土壤类型的垂直分布,以及经营措施作了较详细的阐述。指出亚高山草甸带下发育着亚高山草甸土,针叶林带下发育着棕壤土,针阔混交林带下发育着淋溶褐土,灌草丛及农垦带下发育着褐土性土和栗褐土。     

Effect of recurrent fires on soil nutrient dynamics in a tropical dry deciduous forest of Western Ghats,India

The role of forest fires in the soil dynamics and global carbon cycle has not been comprehensively studied in tropical forests as the effects of fire on tropical forest soils can be extremely variable. This study was aimed to understand how repeated fires affect physical and chemical properties of soil in a tropical dry deciduous forest and alter soil fertility and health. The study was carried out in the dry deciduous forest of Mudumalai Tiger Reserve. Soil samples were collected from unburned (B0) to six-time burned (B6) plots. Samples were collected from each plot from three different depths viz. 0–10 (Top), 10–20 (Middle), and 20–30 cm (Bottom) and analyzed for soil physical and chemical properties. Soil pH, EC, WHC decreased with increasing fire frequencies while bulk density increased. Organic Carbon, Total N, and available P decreased with increasing fire frequencies whereas extractable K initially increased but decreased with the very high frequency of fires. NO₃^?N slightly decreased with high fire frequencies but NH₄^?N decreased significantly with increasing fire frequency. These results provide a new insight regarding the influence of repeated fires on soil that will be valuable to understand the effect of fire on the recovery of soils and nutrient dynamics.