Forest fire as an ecological factor is a highly broad and complex one. The research on fire in nature has hundreds of papers annually and seems to be growing at an ascending rate. It is difficult to compress small amount of the available literature on aspects of fire as an ecological factor into this essay.

Forest Fire – As an Ecological Factor

For this reason this essay will emphasize the effects of fire on ecosystem properties that are important for plant growth and development and on the influence of fire on growth and reproductive characteristics of plants and effects on ecology.  Forest fire is a fire in an area of combustible vegetation occurring in rural areas.

Forest Fire occurrence throughout the history of terrestrial life invites conjecture that fire must have had pronounced evolutionary effects on most ecosystems’ flora and fauna.[1] Many plant species depend on the effects of fire for growth and reproduction.[2] Wildfires in ecosystems where wildfire is uncommon or where non-native vegetation has encroached may have strongly negative ecological effects.[3]

1-Forest Fire as an Ecological Factor

  • Fire Ecology

Fire ecology concerned with natural processes containing fire in an ecosystem and the ecological impacts, the relationship between fire and the abiotic and biotic components of an ecosystem. Forest fires are general in climates that are mostly moist to allow the growth of vegetation but dry and hot periods. Most species types of North American forests evolved with fire, and many of these species depend on wildfires, and particularly high-severity fires, to reproduce and grow. Fire provides service to restoration nutrients from plant matter back to soil, the heat from fire is important to the germination of some types of seeds, and the snags (dead trees).

Early successional forests created by high-severity fire support some of the highest levels of native biodiversity found in temperate conifer forests.[4][5] Global warming and climate changes are causing an increase in temperatures and more droughts nationwide which contributes to an increase in wildfire risk Although some ecosystems depend on naturally fires to regulate growth, some ecosystems suffer from too much fire, as the chaparral in southern California and lower-elevation deserts in the American Southwest. The increased fire frequency in these ordinarily fire-dependent areas has upset natural cycles and damaged native plant communities.

Because they are highly flammable, they can increase the future risk of fire, creating a positive feedback loop that increases fire frequency and further alters native vegetation communities.[6] In the Amazon Rainforest, drought, logging, cattle ranching practices, and slash-and-burn agriculture damage fire-resistant forests and promote the growth of flammable brush, creating a cycle that encourages more burning.[6] Fires in the rainforest threaten its collection of diverse species and produce large amounts of CO2.[7]. A combination of images taken at a photo point at Florida Panther NWR. The images are panoramic and cover a 360 degree view from a monitoring point. These images range from pre-burn to 2 year post burn.

1.2 Forest fire and ecological succession

Fire effects are different in every ecosystem and the organisms in those ecosystems have adapted according to fire effects. One common thing is that in all ecosystems, fire creates a mosaic of different habitat areas, with areas ranging from those having just been burned to those that have been untouched by fire for many years. This is form of ecological succession in which a freshly burned site will progress through continuous and directional phases of colonization following the destruction caused by the fire. [8] Ecologists commonly summarize succession through the changes in vegetation that successively arise.

After wildfire the first species to germinate will be those with seeds are already present in the soil, or those with seeds are able to travel into the burned area quickly. These are commonly fast-growing plants that require light and are intolerant of shading. As time passes, more slowly growing, shade-tolerant woody species will suppress some of the herbaceous plants. [9] Conifers are often early successional species, while broad leaf trees frequently replace them in the absence of fire.

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Hence, many conifer forests are themselves dependent upon recurring fire.[10] Different kinds of plants, animals, and microbes specialize in exploiting different stages in this process of succession, and by creating these different forms of patches, fire allows a greater number of species to exist within a landscape. Soil properties will be a factor in determination the specific nature of a fire-adapted ecosystem, as will climate and topography

1.3 Plant adaptation

Vegetation in forest fire-prone ecosystems often survives through adaptations to their local fire regime. Such changes include physical protection against heat, increased growth after a fire event, and flammable materials that encourage fire and may eliminate competition. For example, plants of the genus Eucalyptus contain flammable oils that encourage fire and hard sclerophyll leaves to resist heat and drought, ensuring their dominance over less fire-tolerant species. [11][12] Dense bark cover, shed lower branches, and high water content in external structures may also protect trees from rising temperatures.

Fire-adopted seeds and reserve shoots that sprout after a fire encourage species preservation, as embodied by pioneer species. Fire Smoke, charred wood and heat can stimulate the germination of seeds in a process called serotiny. Smoke from burning plants increase germination in other types of plants by inducing the production of the orange butenolide. Chamise dead wood litter is low in water content and flammable, and the shrub quickly sprouts after a fire. 

Sequoia rely on periodic fires to reduce competition, release seeds from their cones, and clear the soil and canopy for new growth.[13] Caribbean Pine in Bahamian pineyards have adapted to rely on low-intensity, surface fires for survival and growth. Balanced fire frequency for growth is every 3 to 10 years. Frequent forest fires favor herbaceous plants, and infrequent fires favor species typical of Bahamian dry forests.Ecological succession after a forest fire in a boreal pine forest next to Hara Bog, Lahemaa National Park, Estonia. The images were taken one and two years after the fire.

1.4 Atmospheric effects

Mostly Earth’s weather and air pollution resides in the troposphere, the part of the atmosphere that extends from the surface of the planet to a height of about 10 kilometers (6 mi). The vertical lift of a thunderstorm or pyrocumulonimbus can be increased in the area of a large wildfire, which can propel smoke, soot, and other particulate matter as high as the lower stratosphere. [14]

Previously, prevailing scientific theory held that most particles in the stratosphere came from volcanoes, but smoke and other wildfire emissions have been detected from the lower stratosphere. [15]. Satellite data of smoke plumes from wildfires revealed that the plumes could be traced intact for distances exceeding 1,600 kilometers (1,000 mi). Computer consisting models such as CALPUFF may help predict the size and direction of wildfire-generated smoke plumes by using atmospheric dispersion modeling.

Forest fires can affect local atmospheric pollution, and release carbon in the form of carbon dioxide. Forest fire emissions contain fine particulate matter which can cause cardiovascular and respiratory problems. Increased fire emissions in the troposphere can increase ozone concentration beyond safe levels.

Indonesia forest fire 1997 were estimated to have released between 0.81 and 2.57 gigatonnes (0.89 and 2.83 billion short tons) of CO2 into the atmosphere, which is between 13%–40% of global carbon dioxide emissions annually from burning fossil fuels. [16][17] Atmospheric models suggest that these concentrations of sooty particles could increase absorption of incoming solar radiation during winter months by as much as 15%.

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1.5 Human risk exposure and airborne hazards

Forest fire have a threat to human populations. The releasing of hazardous chemicals from the burning of wildland fuels significantly impacts health in humans. Wildfire smoke is composed primarily of carbon dioxide and water vapor. Other common smoke components present in lower concentrations are carbon monoxide, formaldehyde, acrolein,  polyaromatic hydrocarbons, and benzene.[18] Small particulates suspended in air which come in solid form or in liquid droplets are also present in smoke. 80 -90% of fire smoke, by mass, is within the fine particle size class of 2.5 micrometers in diameter or smaller.

The concentration of Carbon dioxide’s high in smoke, it poses a low health risk due to its low toxicity.  Some chemicals are considered to be significant hazards but are found in concentrations that are too low to cause detectable health effects. The severity of fire smoke exposure to an individual is dependent on the length, severity, duration, and proximity of the fire. People had affected directly to smoke via the respiratory tract though inhalation of air pollutants.

Communities are exposed indirectly to wildfire debris that can contaminate soil and water supplies. The United State Environmental Protection Agency (EPA) created the Air Quality Index (AQI), a public resource that provides national air quality standard concentrations for common air pollutants. The public can use this index as a tool to determine their exposure to hazardous air pollutants based on visibility range. [19]

1.6 Effects of fire on major forest ecosystem processes

Fire and its relation with ecology are among the best-studied topics in contemporary ecosystem ecology. The large numbers of existing research on fire and fire ecology indicates an urgent need to synthesize the information on the pattern of fire effects on ecosystem composition, structure, functions for application in fire and ecosystem management. Summarizing the fire effects and underlying principles are critical to reduce the risk of uncharacteristic wildfires and for proper use of fire as an effective management tool toward management goals.

Forest fire can shape ecosystem composition, structure and functions by selecting fire adapted species and removing other susceptible species, releasing nutrients from the biomass and improving nutrient cycling, affecting soil characteristics through changing soil microbial activities and water relations, and creating heterogeneous mosaics, which in turn, can further influence fire behavior and ecological processes.

Forest fire as a destructive force can consume large amount of biomass and cause negative impacts such as post-fire soil erosion and water runoff, and air pollution. The impacts of fire on an ecosystem depend on the fire regime, vegetation type, climate, physical environments, and the scale of time and space of assessment. More ecosystem-specific studies are needed in future, especially those focusing on temporal and spatial variations of fire effects through long-term experimental monitoring and modeling. [21]

Mostly forests have evolved to utilize fire disturbances to maintain ecosystem health and to regenerate. For example, many plants species actually require fire to germinate their seeds, and forest fires return important nutrients to the forest soil that was previously being stored in biomass. Forest fires help to clear out dead wood and other materials that would otherwise have taken much longer to break down and provide soil nutrition for the next generation of trees and Burned  forest plants serve as plants living in that forest.

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This process serves to keep a forest ecosystem healthy. important habitat for many species, such as the Black-backed Woodpecker, Picoides arcticus, that is specialized to live and thrive in forests that have experienced severe burning.  At one time in the not-too-distant past, it was common forest management policy to suppress and control forest fires as much as possible due a general lack of understanding of fire’s importance in the ecological health of forest ecosystems.

When forest fires are continuously suppressed, large amounts of dead biomass accumulates on the forest floor, increasing the risk for more frequent and much more intense wildfires than otherwise when they finally do occur. The current understanding of forest fires as a natural and healthy part of forest ecosystem ecology, forest management efforts typically are now focusing on a combination of containment where necessary to protect human communities, as well as periodic fires for the sustainability and health of forest ecosystems.[22]

Mostly forests have evolved to utilize fire disturbances to maintain ecosystem health and to regenerate. For example, many forest tree species require fire to germinate their seeds, and forest fires return important nutrients to the forest soil that was previously being stored in biomass. Forest fires help to clear out dead wood and other materials that would otherwise have taken much longer to break down and provide soil nutrition for the next generation of trees and plants living in that forest. These processes help to keep a forest ecosystem healthy.

Burned areas of forest serve as important habitat for many species, such as the Black-backed Woodpecker, Picoides arcticus, that is specialized to live and thrive in forests that have experienced severe burning. When forest fires are continuously suppressed, large amounts of dead biomass accumulates on the forest floor, increasing the risk for more frequent and much more intense wildfires than otherwise when they finally do occur. This puts communities at an increased risk for damage from these more intense fires.

Also, the plants that do grow in such forests are much more densely packed than they would otherwise have been. With the understanding of forest fires as a natural and healthy part of forest ecosystem ecology, forest management efforts typically are now focusing on a combination of containment where necessary to protect human communities, as well as periodic fires for the sustainability and health of forest ecosystems.

Conclusion:

The study of Fire ecology is important because it regulate different ecological cycles It has impacts on plantation, biodiversity, soil fertility and increase food web for habitats etc. So, the concept that forest fire is not good is not true it is bad or good depend on its severity. Sometime artificial fire is important for new vegetation and to burn forest residues, new grasslands, food for many organisms etc. Forest fire impacts as ecology factor because it have directly or indirectly relationship with ecology. So, it is important to study the relationship of forest fire with ecology to keep natural balance ecosystem.

Inam Khan 1 Muhammad Roman 2, Sarwan Khan2, Sadam Husain3,

School of Soil and Water Conservation, Beijing Forestry University, China

Muhammad RomanArticlesecological,factor,Fire,ForestForest fire as an ecological factor is a highly broad and complex one. The research on fire in nature has hundreds of papers annually and seems to be growing at an ascending rate. It is difficult to compress small amount of the available literature on aspects of fire as...Pakistan's Only Newspaper on Science and Technology
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