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Forest Fire

 

 

By Giovanni Bovio

Текст № 1

F

ire management planning requires the coordination of a vast array of forest information as well as data on silviculture, forest management, and land use. Over the last 40 years Italy has tackled the problem of forest fires in a number of ways.

During the 1960s, there was increasing awareness that greater control of forest fires could be achieved by adopting a wider perspective. Researchers investigated general forest protection (Volpini 1967), silviculture and management (Feliciani and Cas-tellani 1967), and a broader knowledge base (Hofmann 1967). Managers began to realize the need for fire management plans and data on fire prevention and extinction.

Controlling Legislation

Italy is divided into 20 regions, which are further subdivided into provinces.

The regions contain forested areas that

differ significantly from each other. As a

result,, forests in various regions are

damaged by fire to different extents (fig. 1) and during different seasons. How-ever, the distribution of fire frequency, total area burned, and forested area burned has been fairly consistent during the past 20 years.

In the 1970s, individual regions began to draft laws specifically addressing the problem of fire. National statute 47, passed in 1975, called for appropriate national fire management plans and included instructions on fire prevention

 

An Evolution of Control Measures in Italy


Текст № 1
and extinction. The Decree of the Presi-dent of the Republic 616/77 applied the same legislation to regional authorities.

Plans had to specify the level of danger in different areas of the country, and indicate the nature and position of any equipment and instruments required. Plans were to be periodically revised, emphasizing rapid development of "protection against forest fires." Operations were to be constantly updated according to new developments in knowledge and techniques. The increasing importance placed by society on forests and their role also had to be taken into account.

Plans implemented in the second half of the 1970s largely addressed fire extinction by identifying the best solution for specific forest environments. The goal at that time was to extinguish fires whenever and wherever they broke out, often without even drawing up a list of operational priorities. This led to defensive systemsthat is, intervening only after a fire had actually broken out (Leone 1988).

A Twofold Approach

During the last few years, however,

plan emphasis has gradually changed. For

example, greater focus has been placed on rating fire danger and on fire detection, a trend also seen in other European countries. In addition, guidelines are more often included for restoring a forest after it' has been damaged by fire. '

The latest development in Italy, especially during the revision process, is to identify two types of areas: those where fire must be avoided at all costs, and those where fire is allowed up to certain preset limits (usually related to cover type).

This perspective—that fire may be allowed to burn a part of the total area covered by the plan—represents an inevitable evolutionary stage. Especiall/for large areas, operations large enough to totally exclude fires are simply not practical. Fur-thermore, fire management costs for vast areas would not be cost-effective. Even [if every flame front could be totally contained in planning areas less than 20,000 hectares (Bovio 1991), the same would not be possible for larger regions. In fact, achieving the conditions necessary to exclude fire entirely would involve massive operations and unrealistic costs.

Efforts to expand forest prevention have encountered other restrictions.

About 66 percent (57,300 square kilometers) of Italy's forested area is privately owned. It would be extremely difficult to implement a uniform plan since few owners are willing to pay for any preventive measures, especially in areas where the right to cut wood docs not yield a profit.

Also, many owners are not prepared to implement fire prevention measures even when public funds arc available.

Acquiring Information

When fire is tolerated to a degree, the

limits depend on forest type. Thus a current goal is to identify forest types in order to forecast fire behavior accurately-particularly intensity, flame height, rate of spread, and residence time. These criteria then form the basis for evaluating the size of the operations required, both in areas where fire is mot tolerated and in those where it is accepted up to certain limits. The larger the area involved, the more the balance must shift toward fire extinction rather than prevention. V

In order to apply the criteria described above, planners need information about the areas designated for either total exclusion or limited intervention—particularly the most serious probable behavior of the fire (based on the conditions that determine and favor fire); maximum intensity admissible for different forest covers; and actions necessary to ensure that the maximum intensity is not exceeded.

Effective fire management plans must

contain reliable predictions, both general and specific, about expected fire behavior in the area under review. Primary factors to be identified include the quantity and type of the combustible biomass and biovolume, the nature of the habitat, topography, and meteorological conditionsall important indicators of flame movement. Unfortunately, such investigations are expensive. Fuel models can simplify the evaluation of pyrological specifications; it is then possible to predict fire behavior by applying mathematical models (Rothermel 1983). Although such models have been used in the United States (Anderson 1982), they have to be adapted to Italian conditions and forest types. And collecting vegetation data for large areas, particularly biomass, can prove onerous.

For these reasons, increasing use has been made of satellite images to map ground cover and monitor changes (d'Angelo et al. 1991). Satellite survey-


 

26 Journal of Forestry


ing, while it cannot provide fuel models, represents a valid method to assess forest cover at a moderate cost. Satellite images also provide a picture of surfaces affected by fire in the recent past (Bovio et al. 1990), and a large view of the entire territory helps define level of danger in the areas to be protected.

Associated Activities

An increasing tendency in Italy is to consider not just combustible forest cover but also all the activities that influence it.

Each area is examined for present forest type_and that which will develop during the plan's time period. In addition, management of forest stands, grazing areas, and wildlife all have considerable influence on the environment and fire clanger level. Silvicultural activities may reduce the hazard level. The distribution and use of grazing areas is closely related to invasive shrub and tree species. Wildlife regulation often involves interventions on fuel loading.

An analysis of these and other variables (such as weather) can help define appropriate countermeasures and set priorities for both fire prevention and extinction. Although extinction was overemphasized in the past, most modern plans balance these two important areas, clearly defining their respective contributions. Preventive operations ensure a reduction in the intensity of the flame front and are complementary to, not independent of, extinction measures.

Firefighter crews can work more efficiently and effectively in areas where prevention measures have been instituted to reduce the fuel load and other factors.

Rating areas for danger increases the efficiency of spotting fires and extinguishing them promptly. Numerous studies are under way to establish reliable fire danger ratings and improve the network of meteorological data. Some regions have propeted the use of meteorological radar, which can measure precipitation quickly and at a moderate cost.

Detection and Control Measures

In Italy, fire detection is done from the air, from ground towers, and lately with automatic detection systems based on infrared emissions. National legislation bills 38/90 and 65/91 allocated enormous sums of money to build permanent monitoring systems in regions that have experienced the greatest damage from fires.

Detection points were established based on the forest areas that present the greatest value and the greatest risk. Points were selected for the widest view over the ter- < rain. Correct positioning of these structures is important because construction and operation costs are high.

Alarm signals are generally transmitted ю a single coordination point by tele- - phone cable—not an instantaneous event, but nonetheless in useful time and at a lower cost than 'real-rime* signals.

Centralized transmission of fire detection

information makes it possible to control

extensive areas with few personnel. In addition, operations can be coordinated by

the same persons who initially register the

alarm. The central location must have all

the relevant data—accurate meterological data, maximum fire intensity allowed,, prevention infrastructure available, forest specifications—and be able to transmit it to firefighting crews.

In Italy, "active-green" firebreaks (with vegetation permanently converted to low-fuel cover types and trees retained to create shade) and water storage provisions are preferred because they considerably reduce the intensity of the flame from and thereby facilitate fire extinction.

Green firebreaks are widely used where the mountainous topography does not favor larger, passive firebreaks. Mainte-nance is easier since clearing individual trees, as well as maintaining the natural . scenery, helps promote the growth of heliophilous plants.

Water supply points must have a minimal effect on the environment and must fulfill the capacity and location requirements of fire crews (based on probable fire behavior). To meet these criteria, Italy tends to establish many small-capacity storage points. Little use is made of concrete structures; instead, priority is given to weather-resistant tanks that can also be disassembled and relocated.

Summary

Fire planning in Italy is moving toward a global view of the problem, with a detailed examination of the character of the woodland and its management.

Computer systems make it possible to identify all the necessary connections between various sectors, particularly for prevention methods, firefighter crew information, and restoration efforts.

Fire management in Italy has developed rapidly, particularly over the last 10 years. Increasingly, management plans arc seen as part of a larger plan to reduce the area of forest affected by fire. More importance is being attached to territory analysis to make fire containment more effective. This is now the primary goal of Italy's effort—the coexistence of all the forest's functions.

 

Literature Cited

Anderson, H.E. 1982. Aids to determining fuel models for estimating fire behavior. USDA For. Serv. Gen. Tech. Rep. INT-122. 22 p.

Bovio, G. 1991. La protezionc dagli incendi boschivi nella pianificazione forcstale. Seminario II bosco e i suoi valori: esperienze e prospective per la pianificazione fbrcstaie. Uninione Nazionale Instituti Forestall, Brasimonc, It-alv.

Bovio, G., R. Manca. and E.G. Perona. 1990.

Individuazione di incendi botchivi con immagini tdcrilevate. Mono e Eoschi 4:5-10.

d'ancelo, M., G. Bianco, P. Podda, and R.

Sardu. 1991. Monitoraggio dci cambiamcnti dclla copertura cd uso del suolo mediante dati multitemporali da satellite (Landsat 5-TM). Convegno Monitorare I'arabicntc agrario e fbrcstaie. Centra di Studio per I'Ap-plicazione dell'Informatica in Agricoltura, Consiglio Nazionale dellc Riccrche, Porto Conic, Italy.

Feuoani, a., and C. Castellani. 1967. Asscsta-mcnto fbrcstaie in funzione dclla difesa antincendi e programmazione dclla prcvenzione ed estinzione. Atti del convegno "L'incrcmento del patriraonio forcstale e la sua difesa dal fuoco." Camera di Commercio Industria с Artigianato, Bergamo.

Hofmann, A 1967. La riccrca scientifica, tecno- . logica ed applicata nella lotta contra il fuoco in foresta in Italia. Atti del convegno "L'incrc-mento del patrimonio forcstale e la sua difesa dal fuoco." Camera di Commercio Industria e Artigianato, Bergamo.

Leone, V. 1988. Aspcrri e limiti dell'artuale dispositive difensivo contra gli incendi boschivi.

CcUulosa e Сапа 39(5): 15-21.

Rothermel, R.C. 1983. How to predict the spread and intensity of forest and range fires.

USDA For. Serv. Gen. Tech. Rep. INT 443. 464 p.

Volpini. C. 1967. La difesa del bosco dal fuoco.

Atti del convegno "L'incrcmento del patrimonio forcstale e la sua difesa dal fuoco." Camera di Commercio Industria e Artigi-anato, Bergamo.

 

 

ABOUT THE AUTHOR

Giovanni Bovio is associate professor, De-partment of Agronomy, Silviculture, and Land Management, University of Turin, Via L. Da Vinci, 44, 1-10098 Grugliasco (TO), Italy.


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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