Forest Fire Paper

7/29/2019 Forest Fire Paper

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Fire and Forest Health

Philip Worlanyo Dugbley

Department of Silviculture

Faculty of Forest Sciences

Bogor Agricultural University, Indonesia

E-mail:[email protected]

Abstract

Without forests humans can not survive. Forests are vital parts of our environment and their

benefits are immeasurable. Forest fires are sometimes essential for forest regeneration but also

detrimental if repeated systematically in the same area. Thus, forest fires can have positive and

negative effect on forest, and its impact on forest health and vitality varies greatly depending on

its usage and frequency of occurrences. Fire is a natural disturbance that occurs in most

terrestrial ecosystems. It is also a tool that has been used by humans to manage a wide range of

natural ecosystems worldwide. As such, it can produce a spectrum of effects on soils, water and

forest ecosystems. This at the long run usually has significant effect on forest health. There are

several management techniques and tools that are used to manipulate a forest to meet specificobjectives. When it comes to forest health and maintaining fire-dependent ecosystems, there is

no better tool than prescribed fire. The use of prescribed fire is a great tool for silvicultural,

ecological, and wildlife management purposes. Fire scientists, land managers, and fire

suppression personnel need to evaluate fire effects on these components, and balance the overall

benefits and costs associated with the use of fire in forest ecosystem management.

Keywords: Prescribed and wildfires; Forest health; Forest soil and ecosystem; Fire eco principle
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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1.0 Introduction

There have always been forest fires and no one can avoid them because in places such as the

temperate zones, fires can occur naturally. Many forests have evolved with fire and recurring

burns help plant and wildlife to thrive. Fire from any unban inter-phase can play a major role in

restoring forest health. However, the use of fire in restoring forest health is a challenge, since

forest is a community of different plants species. Therefore, the resistance and resilience of a

forest must be taken into consideration. Thus, the ability of the species and forest as a whole to

withstand drought are heavily impacted.

In past years, fire was hazardous for small trees, but recently insect and diseases have replaced

the perceived fire effect. Fire has therefore become an important tool in controlling insect pests

and diseases. In harsh conditions such as during drought, plants become susceptible to beetle

insects and diseases. Fires in forests produce some of the most profound impacts on almost allecosystems. Wildfires and prescribed fires affect the vegetation, soils, wildlife, and water

resources of watersheds. They impose a wide range of effects depending on the mosaic of fire

severities and post-fire hydrologic events. For example, changes in soils after fires produce

varying responses in the water, floral, and faunal components of forest ecosystems because of

their complex interdependencies (DeBano, 2000). The effects of fire on soils are a function of the

amount of heat released from combusting biomass, the fire intensity and the duration of

combustion. Since forest health is also somehow affected by soil conditions, it will be wealth

stating the impact of fires on forest soils.

The objective of this paper therefore, is to summarize the possible impacts of fires (both wild and

prescribed) on forest health; including forest soils and its ecosystem.

2.0 Fire Ecology Principles

Forest ecosystems, most importantly those of the western part of the world, had evolved under

regimes of periodic forest fires (Vale, 1982). Its important to note that healthy forests do burn.

This is partly a result of summer drought conditions that characterize many portions of the West.

In much of the Western parts, temperatures tend to be warmest when conditions are driest.

These factors are unfavorable for biological decomposition by bacteria, fungi, and other

decomposers. As a result, decomposition is often extremely slow.


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Nutrients are locked up, and unavailable for further growth. Litter that falls to the forest floor

gradually builds up. In Western Europe, fire, more than any other factor, is responsible for

recycling the nutrients in this dead plant material. Deprived of periodic fires, most western

ecosystems gradually decline in productivity for lack of available soil nutrients. In contrast,

under natural conditions, net nutrient levels often increase after a fire (White, 1985). The

periodicity between fires varies from ecosystem to ecosystem. For instance, in dry, low-elevation

ponderosa pine forests of the Southwest, before the era of fire suppression, fires once burned

almost every 3 to 20 years.

Long before fire suppression had any influence on fuel loading, there was huge forest fires

associated with the Western Europe. In 1910, for example, more than 3 million acres burned in

northern Idaho and western Montana, including many low-elevation areas characterized by

frequent low intensity fires (Sargent, 1993). The conditions for a major burn often have more to

do with drought, wind, and ignition sources than with fuels. Also, since young trees have poorly

developed root systems, young trees are among the first to experience drought stress and are

extremely flammable. Thus activities like salvage logging may actually increase the likelihood

of major fires, rather than reduce it, by increasing the amount of young forest re-growth.

3.0 Impact of Fire on Forest Soil

Both prescribed and wild fires definitely produce large impact to forests ecosystem and health.

Physical impacts of fire on soil include breakdown in soil structure, reduced moisture retention

and capacity, and development of water repellency, all of which increase susceptibility to

erosion. These fires increase water repellency in forest soil, which results into infiltration and

soil erosion. Fires also affect soil colour, pH, bulk density, texture, and so forth (Chandleret al.,

1983)

Chemical changes in soil after forest fire is very significant. This is because changes in nutrient

cycle and soil organic matter can change the productivity of forest ecosystems. Fire-impacted

soils experience changes in nutrient pools cycling rates, loss of elements to the atmosphere, and

loss of organic matter. The effect of forest fire on soil organic matter (SOM) varies from

complete combustion to increase in its amount and the effect on nitrogen is also variable.


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Most studies have reported increase in the total plant available forms of nitrogen, ammonium

(NH4+) but reduction in the amount of total nitrogen. This reduction in the nitrogen is because of

volatilization. Other nutrients are less affected in comparison to nitrogen. High availability of

nutrients results into this sudden flush of nitrogen in the soil followed by a rapid growth of

herbaceous plants and a significant increase in plant storage of nitrogen (Kutiel and Naveh,

1987).

Biological properties of soil are also highly affected. Of the three main properties of soil, soil

biological properties is the most and easily affected component. This is due to the sensitivity of

microorganisms and invertebrates towards high temperatures. Biological properties are altered

by changes or loss of microbial species and population dynamics, reduction or loss of

invertebrates, and partial elimination (through decomposition) of plant roots. Although the most

severe impacts on soils occur in stand-replacing wildfires, prescribedd fires can produce local

effects as well. The changing trend is that, fire decreases the number and species richness of both

soil-dwelling invertebrates and micro-organisms. But in comparison to micro-organisms, soil

dwelling invertebrates are less affected because of high mobility and burrowing habit. Soil

microorganisms are complex and how they respond to fire will depend on numerous factors,

including fire intensity and severity, site characteristics, and pre-burn community composition.

4.0 Effect of Fire on Forest Ecosystem

Most fires perform a variety of ecosystem services. For example, fires cleanse the forest. Heat

from fires can kill forest pathogens in the soil, including root rots, as well as parasitic insects and

fungi that may be found in fallen trees or snags (Rabkin, 1995). Laboratory studies have

demonstrated that smoke from fires can kill certain arboreal forest pathogens, reducing for a

time, the influence of some tree diseases. Smoke also aids the germination of some plant species.

Fires also change nutrient flows. Dead litter burns and turns to ash. The heat and combustion

change the chemical composition of soils. Depending on how hot they burn, fires can volatilize

certain nutrients, like nitrogen, that are lost as gases into the atmosphere (Vale, 1994). However,

the nitrogen pool available to plants is large relative to most fire-induced losses, and nitrogen is

quickly replaced in the soil through nitrogen-fixing bacteria, which usually increase significantly

after a burn in most ecosystems.


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Studies have also shown that, bacteria and other nitrogen fixers typically make up all the

nitrogen losses to volatilization within two years of a burn. Other important plant nutrients,

including phosphorus and calcium, are released from litter by fires and leached into the top

layers of the soil. Despite some losses to waterways and the atmosphere, the overall effect of all

but the most intense fires is the redistribution of nutrients from the forest canopy and floor into

the soil, thus increasing soil fertility.

Figure 1.0___

Immediate and long-term ecosystem responses to fire. (Adapted from Borchersand Perry 1990. In: Natural and Prescribed Fire in Pacific Northwest Forests, edited by J.D.

Walstad, S.R. Radosevich, and D.V. Sandberg).


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5.0 Impact of Prescribed and Wild Fires on Forest Health

Basically, there are two types of forest fires: prescribed (controlled) fires and wildfires.

Prescribed fireis the controlled application of fire to naturally occurring vegetation under

exacting weather conditions, in a definite place, for a specific purpose, to achieve particular

results. Prescribed burning of naturally accumulated forest floor materials or slash following tree

harvest is also a standard practice to reduce fuel levels, with the intention of minimizing the

extent and severity of wildfires or facilitating germination and growth of desired forest species.

They are primed when soil is moderately moist, and consequently they show a low severity

(Walstad et al. 1990).

In contrast, wildfiresgenerally occur in the presence of

an abundant and dry fuel load and, thus, are very severe.

However, due to the inhomogeneous spatial distribution

of severity, naturally burnt soils often appear as chaotic

mosaics of areas little affected by the fire alternating

with others seriously impacted (Rab, 1996).

Soil properties can experience short-term, long-term, or

permanent fire-induced changes, depending chiefly

on type of property, severity and frequency of fires,

and post-fire climatic conditions after fire occurrences. Fire can be detrimental or advantageous.

Several aspects of fire, such as heat, intensity, timing, and frequency, can be manipulated to meet

a desired objective. To maintain a healthy ecosystem, the biological characteristics within a stand

are changed through manipulation. Used correctly, fire is a good tool to accomplish land

management objectives. There are several reasons for using prescribed fire. For a fire to occur,

three elements are needed in sufficient quantities namely; fuel, oxygen and heat.

Prescribed fire is a good tool to reduce fuel loadwithin a stand to prevent uncontrollable

outbreaks of wildfires in most forest situations. Site-prep fires reduce debris loads after a harvest

event and also enable easier planting, giving the seedlings a head start on their competition with

other plants. Prescribed fire, or controlled burning, plays many roles in the management and

manipulation of forestlands. It also plays an important role in improving the health and diversity

of certain forestland types.

Figure 1.1 Forest Wild fire


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Habitats are made available for wildlife that would otherwise not have existed. Fire set within

developing stands of forest tress will also open up the soil, allowing sunlight to reach the forest

floor and stimulate the growth of new forbs and browse. This will benefit numerous wildlife

species by adding diversity to the food supply and other fire-adapted plant and animal species

will begin to thrive as well.

6.0 Summary and Conclusion

Prescribed and wild forest fires have multiple impacts on environmental factors such as soil, air,

water, wildlife, and fire-dependent plant species. One natural function of fire is rejuvenation,

thus, it recycles substances such as nutrients. Controlled burning therefore is a valuable and

irreplaceable management tool foresters and wildlife managers utilize to meet desired

management objectives. Unfortunately, the inability to use scientific forestry practices, such as

selective harvest, has lead to catastrophic forest fires that endanger forest and even forest fringe

communities. Policies are needed that will provide sustainable timber yields and give forest

managers the necessary tools to effectively manage forests and prevent wildfires.

In order to keep our forests healthy, we need to take some actions to:

Prevent the buildup of dangerous flammable material in our forests. Find ways to keep timber-dependent industries alive so we can manage forests and put

forest products to use.

Find the proper balance in managing forests so they will contribute to our economic wellbeing while also providing recreational opportunities

In conclusion, prescribed fire is an important ecological tool and maintaining fire as an

ecosystem process is still an option. For instance, in a research dubbed the TEAKETTLE

GREEK EXPERIMENT with the goal of identifying the effect of fire and thinning on forest

health, scientist found out that burning helps in reducing the amount of shrubs which aid in the

fast establishment and growth of seedlings. Respiration and decomposition also responded

positive to the burning which implies that, fire can enhance certain processes in the forest

ecosystem. Moreover, fire also helps in releasing soil nutrients presumably that are tied up in

organic materials thereby making nutrient more available for plants.


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On the other hand, in the same experiment, thinning aided in reducing moisture stress in forest

trees and making them less vulnerable to pests and diseases. It also helped in reducing lager fuel

tress. After the experiment, scientist on this project suggested that moderate thinning with

frequent use of fire are the best ways to keep teakettl e forest ecosystem healthy.

Researches in other areas of the United States also confirm the value of fire in restoring forests

that evolved with frequent lower intensity burns. The "TEAKETTLE GREEK EXPERIMENT"

contributes to this new understanding that fire plays a vital role in restoring forest health.


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REFERENCES

1. Chandler, Craig; Cheney, Phillip; Thomas, Philip; Trabaud, Louis; Williams, Dave. 1983.Fire in forestry. Vol. 1: forest fire behavior and effects. New York: John Wiley & Sons.

450 p.

2. DeBano L. F. 2000. The role of fire and soil heating on water repellency in wild-landenvironments: a review. Journal of Hydrology, 231-232: 195-206

3. DeBano, L.F., D.G. Neary, and P.F. Ffolliott, 1998. Fires Effects on Ecosystems. NewYork: John Wiley & Sons, Inc. 333 p.

4. Kutiel P, Naveh Z. 1987. The effect of fire on nutrients in a pine forest soil. Plant andSoil, 104: 269-274.

5. R. White (1985):, Introduction: American Indians and the Environment, EnvironmentalReview 9 101103.

6. Rab M.A 1996. Soil physical and hydrological properties following logging and slashburning in the Eucalyptus regnans forest of southeastern Australia. For Ecol Manage

84:159175

7. S. Rabkin(1995):, Portable Magic, Yosemite 57, no. 3 27.8. S. Sargent, 1993 Tuolumne Tomboy, Yosemite 55, no. 3 pp 699. T. Vale and G. Vale, 1994. Time and the Tuolumne Landscape: Continuity and Change

in the Yosemite High Country (Salt Lake City: University of Utah Press.

10.T. Vale, 1982. Plants and People: Vegetation Change in North America (Washington,D.C.: Association of American Geographers).

11.Walstad JD, Radosevich SR, Sandberg DV (eds) 1990.Natural and prescribed fire in thePacific Northwest forest. Oregon State University Press, Corvallis

12.Borchers, J.G.; Perry, D.A. 1990. Effects of prescribed fire on soil organisms. In:Walstad, J.D.; Radosevich, S.R.; Sandberg, D.V. (eds.) Natural and prescribed fire in

Pacific Northwest forests. Corvallis: Oregon State University Press: 143157.

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Forest Fire Paper