Overview of Fire and Smoke Management Issues and Options in Tropical Vegetation

Overview of Fire and Smoke Management Issues
and Options in Tropical Vegetation

Johann Georg Goldammer

GTZ- Integrated Forest Fire Management Project (Samarinda, East Kalimantan, Indonesia) and Max Planck Institute for Chemistry, Fire Ecology and Biomass Burning Research Group; c/o University of Freiburg; PO Box ; D-79085 Freiburg, Germany

Goldammer, J.G. 1997. Overview of fire and smoke management issues and options in tropical vegetation. In: Transboundary Pollution and the Sustainability of Tropical Forests: Towards Wise Forest Fire Management – The Proceedings of the AIFM International Conference (Haron Abu Hassan, Dahlan Taha, Mohd Puat Dahalan, and Amran Mahmud, eds.), 189-217. ASEAN Institute for Forest Management, Ampang Press, Kuala Lumpur, 437 p.

Abstract
Introduction
Tropical Fire Regimes
Fire in the Evergreen Equatorial Rain Forest
Fire in Seasonal Forests
Fire Climax Pine Forests
Savannas and Degraded Woodlands
Fires in Tropical Man-Made Forests
Impacts of tropical wildland fires on atmosphere and climate
Fire Management
Fire Policy and Legal Aspects
Collaboration for Developing National, Regional and International Fire Management Programs
Concluding Remarks
References

Abstract

Fire is an important traditional tool in tropical land management. The use of fire in large-scale forest conversion and the lack of appropriate measures to prevent the spread from land-use fires into protected vegetation has led to unprecedented ecological and environmental problems. The paper provides some general information on various types of fire regimes in the tropics and summarizes options in fire and smoke management.

Introduction

Fires in the forest and other vegetation of the tropics and subtropics and the changing tropical land use have increasing regional and global impact on the environment. The smoke plumes from tropical biomass fires carry vast amounts of atmospheric pollutants, including CO2, CO, NOx, N2O, CH4, nonmethane hydrocarbons, and aerosols. Smog-like photochemistry produces ozone concentrations comparable to those found in the industrialized regions. The consequences of burning of vegetation, such as the aggravation of the greenhouse effect, affect nontropical regions most strongly. The extreme drought and the catastrophic fires in East Kalimantan and the Malaysian provinces on Borneo in 1982/83 indicate the danger that possible climatic changes pose to the survival of the tropical forests themselves. The use of fire in large-scale forest conversion programmes in Indonesia during the following dry years of 1987, 1991, and 1994 led to extended smog episodes, causing problems for human health, visibility and traffic safety in mainland and insular SE Asia.

On the other hand, fires play a central role in the maintenance of many natural ecosystems and in the practice of agriculture and pastoralism. The various types of savannas are burned frequently both by human-and non-human-caused fires. Burning is used as a tool in maintaining tree plantations and natural forests, especially in the subtropics. Forest in the moist tropics have long been used in shifting cultivation to support low population densities of traditional agriculturalist without degrading either the forest or the productive potential of the soil. This situation has changed radically by accelerating shifting cultivation cycles under the influence of market economies and because of increasing population pressure, both from demographic growth and from reduced access to land. Nonsustainable slash-and-burn pioneer agriculture, without the long fallows of traditional systems, is practised by populations that are either attracted to or forced to migrate to tropical forest areas, or that are transported to these regions under government colonization or transmigration programs. Both shifting cultivation and pioneer farmers depend on burning to produce crops at acceptable labor input intensities. Burning is also the key process in maintaining the cattle pastures that are replacing tropical forest in vast areas of the tropics.

Altogether the frequency and negative environmental effects of fires have greatly increased due to human population growth and land-use changes throughout the tropics. However, the dual role of fire must be recognized, being both a natural agent of ecosystem maintenance and a potentially disastrous cause of ecosystem destruction.

Fire and smoke management options in tropical vegetation management must consider these dual effects of fire. Preparation of appropriate fire and smoke management plans involves complex and difficult decisions which in many regions cannot be taken due to the lack of fundamental knowledge and training in fire ecology and management and non-existing technological and infrastructural resources. Fire and smoke management plans must also include the socio-economic and cultural aspects, requiring the integration of the rural population through participatory approaches.

International collaboration is mandatory to ensure appropriate elaboration and transfer of basic knowledge and technologies. This paper gives an overview on tropical fire regimes, atmospheric fire impacts, and options for fire and smoke management. International collaborative programmes in this field are described.

Tropical Fire Regimes

Today most of the human population pressure on Earth is building up in the tropics and subtropics. Here fire is being used extensively as land treatment tool, e.g. for forest conversion to agricultural land, for maintaining grazing lands, and for utilization of the seasonal forests and savannas. Fire influence through traditional burning practises over millenia has strongly favored and selected plant communities that are considered to be sustainable and long-term stable fire ecosystems. However, the contemporarily changing fire regimes and the alteration of sustainable time-space-fire relationships in the wake of changing land-use practises are often associated with severe vegetation degradation processes (cf. synthesis by Goldammer [1990]).

Fire regimes in tropical forests and derived vegetation are characterized and distinguished by return intervals of fire (fire frequency), fire intensity (e.g. surface fires vs. stand replacement fires) and impact on soil. Basic tropical and subtropical fire regimes as distinguished in Figure 1 are determined by ecological and anthropogenic (socio-cultural) gradients.

Lightning is an important source of natural fires which have influenced savanna-type vegetation in pre-settlement periods. The role of natural fires in the “lightning-fire bioclimatic regions” of Africa was recognized early (e.g.Phillips 1965; Komarek 1968). Lightning fires have been observed and reported in the deciduous and semi-deciduous forest biomes as well as occasionally in the rain forest. Today the contribution of natural fires to the overall tropical wildland fire scene is becoming negligible. Most tropical fires are set intentionally by humans (Bartlett 1955, 1957, 1961) and are related to several main causative agents (Goldammer 1988):

deforestation activities (conversion of forest to other land-uses, e.g. agricultural lands, pastures, exploitation of other natural resources);
traditional, but expanding slash-and-burn agriculture;
grazing land management (fires set by graziers, mainly in savannas and open forests with distinct grass strata [silvopastoral systems]);
use of non-wood forest products (use of fire to facilitate harvest or improve yield of plants, fruits, and other forest products, predominantly in deciduous and semi-deciduous forests);
wildland/residential interface fires (fires from settlements, e.g. from cooking, torches, camp fires etc.);
other traditional fire uses (in the wake of religious, ethnic and folk traditions; tribal warfare);
socio-economic and political conflicts over questions of land property and land-use rights.

The fire regimes of selected forest types and other vegetation are briefly described in the following section; additional examples illustrate the role of fire in tropical human-made forests.

Fire in the Evergreen Equatorial Rain Forest

In tropical rain forests three types of forest clearing by fire may be differentiated, (1) shifting agriculture (slash-and-burn agriculture), where land is allowed to return to forest vegetation after a relatively short period of agricultural use, (2) permanent removal of forest for conversion to grazing or crop land, as well as other non-forestry land uses, and (3) complete removel of native forest for preparation of forest plantations (monocultures). In all instances, clearing and burning follows initially the same pattern: trees are felled at the end of the wet season, and the vegetation is left for some time to dry out in order to obtain best burning efficiency. The efficiency of the first burning is variable; it often does not exceed 10-30% of the aboveground biomass. This low burning efficiency is due to the large fraction of forest biomass residing in the tree trunks, only a small portion of which tends to be consumed during the first burn. The remainder is treated by a second fire or is left on the site to decompose.

Shifting agriculture systems in their early practises and extent were largely determined by low human population pressure on the forest resources. They provided a sustainable base of subsistence for indigenous forest inhabitants, and their patchy impacts had little effects on overall forest ecosystem stability (Nye and Greenland 1960; Watters 1971; Peters and Neuenschwander 1988). Today, shifting agriculture is practised by some 500 million people on a land area of c. 300 to 500 million ha, and is becoming increasingly destructive because of larger individual sizes of areas cleared and shorter fallow (forest recovery) periods.

In addition to shifting cultivation, large forest areas are converted for permanent crop and grazing lands. The burning of primary or secondary rain forest vegetation for conversion purposes has been accelerated in the recent years. In 1985 alone more than 26.5×106 ha of forest clearing and rangeland fires were observed in the southern Amazon Basin, thereof c. 8.9×106 ha were forest conversion fires. In 1987 a total of 20×106 ha were burned in the “Amazonia Legal” region; 40% of the burned area was primary forest, the remainder secondary growth (Malingreau and Tucker 1988; Setzer and Pereira 1991).

Fires in the rain forest biome, however, are not always restricted to planned forest conversion. Recent observations of the impact of drought and fires in 1982-83 on the rain forests of Borneo and on the Amazon rain forest have shown that undisturbed perhumid rain forest biomes may occasionally become flammable. Goldammer and Seibert (1990) evaluated the state of information on the extent and impact of rain forest fires in Borneo during the extreme drought of 1982-83, which affected the entire West Pacific Region. Such droughts were reported in both the 19th and 20th centuries and were associated in several cases with rain forest fires. The large area of the fire-affected rain forest was due to numerous fires escaping from forest conversion and shifting agriculture fires, totalling c. 5×106 ha in East Kalimantan and the Malaysian provinces of Sabah and Sarawak. Forest regeneration after fire is described by Goldammer et al. (1996).

It is generally observed that repeated fires in tropical rain forest biomes lead to the invasion of pyrophytic grasses, e.g. Imperata spp. Large tracts of tropical lowlands formerly occupied by rain forest are now degraded Imperata grasslands that are maintained by short fire-return intervals.

Fire in Seasonal Forests

The occurrence of seasonal dry periods in the tropics increases with distance from the perhumid equatorial zone. The forests gradually develop to more open, semi-deciduous and deciduous formations (e.g. moist and dry deciduous forests, monsoon forests). Between a more or less closed deciduous forest (characterized by fuels from the tree layer) and a grass savanna (fuels exclusively grasses) a broad range of ecotones can be found. Since an extreme richness of terminology exists for the non-evergreen forests and for the ecotonal transitions towards savannas, it was suggested that the prevailing fuel type, a parameter more meaningful from the point of view of wildland fire science, be used to distinguish the various formations (Goldammer 1991, 1993). The term “forest” is used if trees and tree residuals are dominating elements of the fuel complex. The main fire-related characteristics of these formations are seasonally available flammable fuels (grass-herb layer, shed leaves) which allow the grass layer, other understory plants (shrub layer) and the overstory (tree layer) to survive and furthermore to take advantage of the regular influence of fire. The most important adaptive traits are thick bark, ability to heal fire scars, resprouting capability (coppicing, epicormic sprouts, dormant buds, lignotubers, etc.) and seed characteristics (dispersal, serotiny, fire cracking, soil seed bank and other germination requirements) (Stott et al. 1990; Goldammer 1993). These features are characteristic elements of a fire ecosystem.

During the dry season the deciduous trees shed the leaves and provide the annually available surface fuel. In addition the desiccating and finally dried grass layer, together with the shrub layer, adds to the available fuel which together generally ranges between 5-10 t ha-1. The fires are mainly set by forest users (graziers, collectors of non-wood-forest products). The forests are underburned in order to remove dead plant material, to stimulate grass growth, and to facilitate or improve the harvest of other forest products. The fires usually develop as surface fires of moderate intensity (usually less than 400 kW m-1; cf. Stott et al. 1990), and tend to spread over large areas of forested lands. The tree layer is generally not affected by the flames, although crowning may occur earlier in the dry season when the leaves are not yet shed. In some cases fires may affect the same area two or three times per year, e.g. one early dry season fire consuming the grass layer and one subsequent fire burning in the shed leaf litter layer. The size of these fires is usually larger than the desired area of impact. This is mainly due to the uniformity of available fuels.

Dry deciduous forests and moist deciduous forests occur on c.250×106 ha and 530×106 ha respectively. No reliable information exists on the extent of recurring fires in these areas. It was estimated that in Burma between 3-6.5×106 ha of forests are annually affected by fire, and a recent report from Thailand estimates an annually burned area of c. 3.1×106 ha, predominantly in dipterocarp monsoon forests (Stott et al. 1990). The analysis of historic information from British India reveals that during the last century and early this century almost all Indian deciduous forest were burned every year (Goldammer 1993).

The ecological impact of the yearly fires on the deciduous and semi-deciduous forest formations is significant. The fire strongly favors fire tolerant trees, which replace the species potentially growing in an undisturbed environment. Frequent fires which remove the protective surface cover (humus, litter) often are the cause of severe erosion. Many of the monsoon forests of continental Southeast Asia would be reconverted to evergreen rain forest biomes if the human-made fires were eliminated.

Fire Climax Pine Forests

Approximately 105 species of the genus Pinus are recognized. From the main center of speciation in Central America and Southeast Asia some species extend into the tropics; there are no pines occurring naturally between the tropics of Africa and in the whole of the Southern Hemisphere except Sumatra. In the tropics the pines are largely confined to the zone of lower montane rain forest. They are usually found on dry sites and prefer a slight to distinct seasonal climate. Most tropical pines are pioneers and tend to occupy disturbed sites, such as landslides, abandoned cultivation lands and burned sites. In the subtropics pines are also found in the lowlands, e.g. in the south of the North American continent.

Besides the pioneer characteristics, most tropical pines show distinct adaptations to a fire environment (bark thickness, rooting depth, occasionally sprouting, high flammability of litter) (Goldammer and Peñafiel 1990). The tropical pure pine forests of Central America and South Asia most often are the result of a long history of regular burning. As in the tropical deciduous forests, fires are mainly set by graziers, but also spread from escaping shifting cultivation fires and the general careless use of fire in rural lands. Fire return intervals have become shorter during the last decades, often not exceeding 1 to 5 years. These regularly occurring fires favor the fire-adapted pines which replace fire-sensitive broadleaved species. The increased frequency of human-caused fires has led to an overall increase of pines and pure pine stands outside the potential natural area of occurrence in a non-fire environment. In the mountainous zones of the tropics fire leads also to an increase of the altidudinal distribution of pines, e.g. by expanding the mid-elevation pine forest belt downslope into the lowland rain forest biome and upslope into the montane broadleaved forest associations (Kowal 1966). These tropical fire climax pine forests are occurring throughout Central America, the mid-elevations of the southern Himalayas, throughout submontane elevations in Burma, Thailand, Laos, Kampuchea, Vietnam, Philippines (Luzón) and Indonesia (Sumatra).

All over the tropical and subtropical world, fire climax pine forests provide a high degree of habitability and carrying capacity for humans. If used properly in time and space, fire creates a highly productive coniferous forest, which grants landscape stability and sustained supply of timber, fuelwood, resin, and grazing land. However, together with the effects of overgrazing (including trampling effects) and extensive illegal (fuel)wood cutting, the increasing occurrence of wildfires tend to destabilize the submontane pine forests and result in forest depletion, erosion and subsequent flooding of lowlands (Pancel and Wiebecke 1981).

Savannas and Degraded Woodlands

The various types of natural savanna formations are potentially of edaphic, climatic, orographic or fire (lightning fire) origin and influenced by wildlife (grazing, browsing, trampling) (cf. Cole, 1986). Together with anthropogenic influences, e.g. livestock grazing, fuelwood cutting and other non-wood product uses, most tropical savannas are mainly shaped at present by regularly occurring human-made fires.

A tremendous variety in physiognomy of the savannas occurs throughout the tropics of Africa, America and Asia. A common feature, however, is the grass stratum, which is an important surface fuel of the open savanna woodlands (tree savannas) and the predominant or exclusive fuel in the grass savannas (grasslands) and in the ecotones between. From the point of view of fire ecology and biomass burning the definition of a savanna ecosystem and its distinction from open forests should be based on the potentially available wildland fire fuel. In this context savannas are defined as those ecosystems in which the grass stratum is the exclusive or predominant wildland fire fuel; open deciduous forests, on the other hand, should predominantly be characterized by available fuels from the tree layer (leaf litter).

The available fuel (the above-ground phytomass density of the grass stratum) per area unit varies with the different bioclimatic and phytogeographic savanna zones (Menaut et al. 1991). In the arid zone of West Africa (Sahel) aboveground biomass ranges between 0.5 and 2.5 t ha-1, in the mesic Sudan zone between 2 and 4 t ha-1, and in the humid Guinea zone up to 8 t ha-1. Fire frequency largely depends on fuel continuity and density. Thus, savannas with relatively high and continuous loads of flammable grasses, such as the Guinean savannas, are subjected to shorter fire-return intervals as compared to the arid savannas. The burning efficiency depends on the moisture content of dead and live organic matter. Fires occurring in the early dry season generally consume less of the aboveground biomass than at the end of the dry season.

The total global area of tropical savannas annually affected by fire and the total global biomass burnt are not known. The main obstacle of obtaining precise data is a lack of reliable vegetation-fire maps based on terrestrial and remote sensing inventories.

Fires in Tropical Man-Made Forests

Litter production in plantations of fast growing exotic species (e.g., Pinus spp. and Eucalyptus spp.) is extremely high and often not in equilibrium with decomposition. The monocultural structure of the plantations and the exclusion of other forest uses lead to accumulation of surface fuels (thick layers of needles/leaves, downed woody debris, shed bark strips) and aerial fuels (draped fuels).

Within their natural range both genera have developed forest formations largely shaped by natural and human-made fires. The role of regularly occurring fires was to suppress fire-sensitive vegetation and to favor the formation of pure stands of fire-resistant pines and eucalypts. Exclusion of fire from the fire climax ecosystems generally leads to build-up of fuels and extreme wildfire hazard (high-intensity stand replacement fires).

During the past decades almost all industrial exotic forest plantations in the tropics were established without considering and introducing recurrent fire as a basic element of stabilizing the biological disequilibrium in fuel dynamics. Consequently, many of these plantations are highly susceptible to high-intensity stand replacement fires.

The introduction of prescribed fire into tropical plantations (or: the restoration of fire into fire ecosystems that were transferred from their native fire environment into a management system in which fire originally had not been integrated) is a new and challenging field of fire research and fire management policies (de Ronde et al. 1990).

Impacts of tropical wildland fires on atmosphere and climate

In recent years increasing attention has been given to the impact of tropical fires on regional and global-scale environmental processes, e.g. the role of tropical fires in biogeochemical cycles and especially in the chemistry of the atmosphere (cf. syntheses by Levine [1991], Crutzen and Goldammer [1993]). A recent estimate of the magnitude of tropical plant biomass burned in shifting agriculture, permanent deforestation, other forest fires and savanna fires revealed that the prompt (gross) release of carbon into the atmosphere from these fires may range between 1 and 3.4 billion tons (1000 to 3400 teragrams [Tg]) (Crutzen and Andreae 1990). Andreae and Goldammer (1992) estimated that ca. 2200 Tg of carbon is being emitted annually to the atmosphere from these tropical fires (see Tab.1). Though the amount of carbon remaining in the atmosphere (net release) is not known exactly, it is generally accepted that the net release of carbon into the atmosphere from permanent conversion of tropical forest into other land uses (deforestation) amounts to ca. 1000 Tg yr-1.

There is still uncertainty on the amount of plant biomass combusted in savanna fires. Although it is is generally agreed that the great part of prompt carbon release is from savanna fires (Crutzen and Andreae 1990; Hao et al. 1990; Andreae and Goldammer 1992), no reliable figures are available on the land area affected by fire and the plant biomass burned annually. Estimates of the amount of carbon released from savanna fires into the atmosphere are given in Table 1.

Although the emissions from tropical vegetation fires are dominated by CO2, many products of incomplete combustion that play important roles in atmospheric chemistry and climate are emitted as well (Crutzen and Andreae 1990). Much of the burning is concentrated in limited regions and occurs mainly during the dry season, and results in levels of atmospheric pollution that rival those in the industrialized regions of the developed world. Photochemical reactions, for instance, in the plumes of vegetation fires may be responsible for as much as one third of the global input of ozone into the troposphere. Recent research has shown that seasonally elevated levels of tropospheric ozone in some tropical regions, particularly over the southern tropical Atlantic Ocean between South America and Africa, are caused by the emissions from tropical wildland fires and subsequent photochemical processes (van Wilgen et al. 1996).

Fire Management

The description of the fire ecology of some selected tropical vegetation types and other ecological implications of tropical biomass burning demonstrate that a general and overall valid statement on the role of fire cannot be made. On the one side, it is clear that fire in the tropics has been used by humans since millenia in successfully cultivating and maintaining valuable forests and open savanna landscapes of high sustainability and carrying capacity. On the other side, in recent years fire has become the most destructive and omnipresent agent in tropical vegetation development.

The tropical forest land manager is challenged to carefully investigate the very specific real and potential role of fire in his area of responsibility, to determine the allowable extent of fire that is compatible with other management and conservation objectives, and to transfer this knowledge into an integrated fire management system.

Fire Policy and Fire Management Options

In the following three basic possible fire policy (or fire management) options in tropical forestry will be highlighted, (1) fire exclusion, (2) no fire management measures at all, and (3) integrated fire management. The ecological and economic implications of these options are summarized in a general scheme (Tab.2). The integrated fire management option embraces all possible treatments as listed in the table (fire exclusion, integration of uncontrolled but tolerable or desired wildfires, and prescribed fire). (Due to lack of space the reader is refered to comprehensive monographs and manuals that cover the basics in fire behaviour, fire management, fire suppression methods and technologies, e.g. Brown and Davis (1973), Luke and McArthur (1978), Chandler et al. (1983) and Pyne et al. (1996).)

Fire Exclusion

The option of fire exclusion is applicable in those forest types, in which any fire effect would be undesirable and counterproductive to the resource management and conservation objectives. Most of the perhumid equatorial rain forests require the strict exclusion of fire if management objectives are not to be jeopardized. This may also apply to plantation-type forests that are stocked by non-fire tolerant tree species. Fire conservancy requires a consequent fire prevention and control approach and the availability of an efficient fire protection organization.

No Fire Management (Uncontrolled Wildfire Occurrence)

The second option (no fire management measures taken) is prevailing in many of the savannas, the savanna-forest ecotones and in open deciduous forests throughout the tropics. Burning patterns (timing of burning, burning frequency) follow traditional land treatment practices or are subjected to chance. In many places there may be no alternatives because of the lack of active control capabilities in land management. As mentioned before, the uncontrolled fire regimes of many fire climax savanna and forest landscapes may be tolerable as long as no additional degradation factors interfere, e.g. excessive grazing. However, the introduction of integrated fire management in many places may increase productivity and sustainability of the vegetation, e.g. a progressive development from a savannized vegetation toward forest.

Integrated Fire Management

The third option, the integrated fire management system, is based on a thorough understanding of the impacts of fire in a specific forest type. It requires the capability to actively manage all fire situations, e.g. to prevent and suppress all undesirable fires, to use prescribed fire in order to obtain resource management goals, and to define and control the threshold between the desired and undesired effects of uncontrolled natural and human-caused fires.

Methods and technologies for implementing either the fire exclusion policy or an integrated fire management system are described in the following sections of fire prevention, fire suppression, prescribed burning, legislation and fire management organization.

Fire Prevention

The prevention of forest fires and other wildland fires embraces a wide range of measures that either modify the fuels around or within the fire-threatened resources so that spread and intensity of fires are modified to such extent that fires can be controlled by the technical means available (fuel management), or reduce the human-caused ignition risks and sources.

Fuel Management

The most important fuels in forest and other wildland fires, which need to be treated, are the surface fuels and the aerial fuels between the surface and the canopy of overstory trees to be protected. The surface fuels (grass-herb stratum, shrubs) are the main carrier of fire, both for horizontal spread and and for build-up of vertical development of the fire. Aerial fuels are all combustibles not in direct contact with the ground, e.g. foliage, twigs, understory tree crowns, which carry the fire into the crowns (“fuel ladders”).

The treatment of these fuels either concentrates on buffer zones (firebreaks or fuelbreaks between wildland vegetation and the forest stands to be protected or by breaking up large continuous forested areas) or is practised inside of the forest stands to be protected.

Fuel management also embraces silvicultural and logging measures which help to minimize the amount of logging slash left after cutting. Recent research in Malaysia shows that careful selective logging will increase the survival of trees and reduction of debris subjected to rottening and fire (Pinard and Putz 1996).

Firebreaks

The construction of firebreaks and fuelbreaks around and inside of a forest complex is a common method of separating fuels (interruption of continuity of fuels). A firebreak is a line of a width up to several meters on which all combustibles are removed and the mineral soil is exposed. The objective of firebreak construction is to segragate, stop, and control the spread of a wildfire. The width of the firebreak varies with fuel loads and expected spotting behaviour (fires jumping over the firebreak). Since fires may easily cross firebreaks of up to several dozen meters, it is often extremely uneconomical to establish and to maintain such large and unproductive strips of land. Furthermore firebreaks in steep terrain tend to erode during the rainy season.

Fuelbreaks with Agricultural Crops

The concept of fuelbreaks is entirely different. Fuelbreaks are generally wide (20-300 m) strips of land on which the native flammable vegetation has been permanently modified or replaced by introduced vegetation so that fires burning into them can be more readily controlled. In the tropics it has been demonstrated successfully that fuelbreaks can be maintained economically by agricultural or agro-silvopastoral land uses.

Agricultural and pastoral land uses usually involve intensive soil treatment and removal of aboveground biomass so that less flammable ground cover is available. A general recommendation for species to be planted on agricultural fuelbreaks cannot be given because of the specific site and climate conditions required. However, some basic principles should be observed. The design of agricultural fuelbreaks should be according to suitability of sites for growing agricultural crops. The selection, treatment and harvest of crops should observe the seasonality of fire danger, e.g. the removal of flammable plant debris at the begin of the period of high fire danger. The integration of millet cultivation (e.g. Pennisetum glaucum, a millet species largely planted as staple food throughout Africa and Asia) on fuelbreak strips may serve as an example for specific harvest planning. The edible parts of millet are usually harvested at the beginning of the dry season, and the remaining biomass (highly flammable stem with leaves) is left on the site until the end of the dry season. In this case it would be required, through contract with the farmer, that the removal of all aboveground biomass has to be finalized before the beginning of the fire season.

If sites are suitable it is preferable to grow creeping plants such as various legumes or groundnuts which will not carry any surface fire due to intensive soil treatment and low and spacy growth.

Pastoral and Silvopastoral Fuelbreaks

The integration of grazing is another method of reducing the flammability of the surface fuels on treeless strips and on “shaded fuelbrakes” (grazing under wide-spaced tree overstory). The grazing resource on the treeless fuelbreaks may occur naturally or may need to be seeded if suitable grass species are not available locally. The impact of “prescribed grazing” (Goldammer 1988) and the browsing of brush and tree succession keeps the total fuel loads down. If grazing and/or browsing is selective, e.g. by leaving certain grass and brush species unaffected, additional mechanical treatment or the use of prescribed burning is necessary in order to further reduce the surface fuel loads. Pastoral fuelbreaks may include firebreaks, e.g. small strips along each side of the fuelbreak; these firebreaks are mandatory if prescribed fire is applied for fuelbreak maintenance (see below).

Shaded fuelbreaks follow a principle similar to the concept of silvopastoral systems. The basic idea of shaded fuelbreaks is to avoid the complete opening of a forest either by firebreaks or by treeless fuelbreaks. It involves the combination of timber production and animal husbandry management. Timber production is restricted to a relatively low amount of trees, which depends on the species used and particularly on the topography of the terrain. The wide distance of spacing produces solitary-type trees. Depending of species involved and timber production goals these solitary trees may need to be pruned regularly (e.g. Pinus sp.). This spatial concept results in breaking the continuity of surface and aerial fuels, both vertically and horizontally.

Shaded fuelbreaks offer a variety of benefits both for pasture and forest management, e.g. reducing the heat stress of grazing animals or reducing plant water stress due to wide spacing and reduced competition. The selection of tree and animal species to be used in an integrated silvopastoral system must be investigated carefully in order to avoid incompatibility of both uses, e.g. possible tree damages caused by animals, etc.

Fuelbreaks Without any Other Land Use

Fuelbreaks that are not utilized for agricultural land uses need to be structured in the same way as the silvopastoral fuelbreaks. The removal of slash (thinning and pruning slash) requires mechanical treatment, e.g. by hand or by using shredding devices to cut the slash to small particles (chipping). These particles remain on the site for improvement of humus layer formation. A compact layer of chipped fuels is generally less flammable. Surface fires creeping on such compact layers are generally easy to control.

The thinning slash can also be removed from the fuelbreaks and burned in piles. The use of prescribed fire on fuelbreaks follows the general concepts as described above.

Fuel Management Inside of the Standing Forest to be Protected

The treatment of surface and aerial fuels inside of the whole area of standing forest to be protected from damages by undesired fires requires careful economic planning. Fuel reduction by mechanical means (e.g. pruning, thinning, removal of understory vegetation, other surface fuels and thinnning slash) requires high investment of labor which may turn out to be very costly. The costs can be reduced if the biomass, which should be removed, is utilized by local population, e.g. for fuelwood.

Fuels inside of those forest and sub-forest types, which are adapted to low-intensity surface fires, can be treated by prescribed fire. Extensive information on techniques is available for conducting safe underburning of plantations in order to reduce the accumulation of fuels…..

Integration and Cooperation with the Rural Population

The vast amount of tropical forest fires and other wildland fires is caused by the rural population. An efficient fire prevention strategy therefore requires an initial understanding of the cultural, socio-economic and psychological background of the tropical fire scene.

It is not surprising that socio-economic and cultural surveys on fire causes often reveal that the most important reason for the careless use of fire is related to the fact that the rural population does not realize the economic and ecological benefits from forests and forest protection. Additionally it is often recognized that rivalries and conflicts between forestry and agricultural land users provoke the intentional and careless setting of forest fires.

The tropical forest fire manager relies extremely on a positive relationship between the people in the rural space and his forest. Mutual confidence and public support can be created by participatory approaches, e.g. by employing people in the forestry sector, especially in fire prevention work (establishing and maintaining firebreaks and fuelbreaks, other fuel treatment). The integration of agricultural and grazing land use into the fuelbreak system, as described before, will also create a high degree of confidence and even dependance (e.g. through a cost-free leasing of fuelbreak land).

Other measures that may stimulate cooperation in fire prevention are “non-fire bonus incentives”. Such an incentive provides funding for villages (or other types of communities) if no fire occurs on specific lands and during specific times. Such programs need to go along with public information campaigns (e.g. through mass media, schools, churches).

Since the use of fire remains to be a vital factor in tropical land use it is recommended that fire management extension services be offered. The extension service should provide information and training in safe and controllable burning techniques. With these techniques it would be possible to contain the fire within the intended area of application and to reduce the risk of human fatalities.

Prescribed Burning

The characteristics of some tropical fire climax forests and sub-forest formations on the one side, and the presence of uncontrolled fire pressure on most tropical vegetation types on the other side require a careful approach in integrated fire management. The introduction of prescribed fire in many cases is mandatory if the productivity of these ecosystems would be endangered by fire exclusion or by fire occurring uncontrolled in time and space.

Prescribed burning is the controlled application of fire to wildland fuels in either their natural or modified state, under specific environmental conditions which allow the fire to produce the fireline intensity and rate of spread required to attain planned resource management objectives. The principles of integrated fire management and the ecological, economic and management aspects of fire management options in tropical vegetation types (Tab. 2) show the broad variety of management objectives to be attained by prescribed burning. In tropical countries the method of prescribed burning is often refered to as “early burning”. This term somewhat expresses the fact that a fire is intentionally set by the forest manager in the early dry season because its effects are to prevent the comparatively more serious effects of a fire occuring uncontrolled during the peak of the dry season.

It is impossible to cover in detail the possible prescribed burning principles, the objectives and the relevant techniques for all tropical sub-forest and forest types. For detailed information on prescribed burning in grasslands and savannas the reader is refered to syntheses by van Wilgen et al. (1990) and Trollope (1996). Extensive experience is also available on prescribed burning in forest management industrial pine plantations (cf. comprehensive summary by de Ronde et al. 1990; Tab.3).

Logging Debris Burning and Smoke Management

Another field of application of prescribed fire in the tropics is the burning of logging debris on clearcuts of degraded natural vegetation which are to be prepared for planting or converted to other land uses. Basically the burning of logging slash on open clearcuts requires less experience because of the lacking overstory to be protected. On the other hand the amount of aboveground biomass burned in forest conversion or clearcut fires is considerably higher than the amount of biomass combusted by underburning. (Total fuel loads after clearcut of tropical rain forests may amount as much as 150 t ha-1 and needs to be burned as complete as possible by high-intensity fires, whereas the surface fuels inside of standing forests range between 2 and 10 t ha-1 and need to be burned with low-intensity fires in order to avoid damages of the standing crop.) Precautions need to be taken in order to avoid (1) uncontrolled spread of fire (escaping fires) into areas not intended to be burned and (2) formation of hazardous smoke emissions.

Both safety hazards can be controlled by burning techniques (ignition and burning patterns) and by observation of other factors that influence fire behaviour, e.g. the spatial arrangement of fuels, fuel moisture, fire weather, etc. Two basic burning patterns are available for logging debris disposal by fire, broadcast burning (use of of backing or heading fire, point source or ring ignition) and pile and windrow burning.

The problem of escaping fires can be solved largely by constructing fire breaks around the area to be burned, or by observing ignition patterns that would drive the fire into the center of the area. The ring fire technique (also refered to as center or circular firing) is useful on clearcut areas where a hot fire is desired to reduce the logging debris as complete as possible and to kill any unwanted vegetation prior to planting. As with the backing fire technique the downwind control line is the first line to be ignited. Once the baseline is secured, the entire perimeter of the area is ignited so the flame fronts will all converge toward the center of the plot. One or more spot fires are often lighted in the center of the area and allowed to develop before the perimeter of the burning block is ignited. The convection generated by these interior fires create indrafts that help pull the outer circle of fire toward the center, thereby reducing the threat of slop-overs and heat damage to adjacent stands.

This technique is very important from the smoke management point of view. In the past years forest conversion fires have created considerable problems in near-surface air pollution. This was mainly due to stable atmospheric conditions (The extended burning activities in the Amazon Basin during the second half of the 1980’s and in Indonesia during the ENSO-related fires of 1982-83, 1987 and again in 1991 created considerable problems in reduction of visibility. Airport facilities and marine navigation had to be closed or reduced during these years. Long-lasting inversion layers over Southeast Asia in September-October 1991 and 1994 trapped the smoke from wildfires and forest conversion fires and caused considerable problems not only in traffic safety but also in human health (respiratory diseases).) and non-appropriate burning techniques, e.g. pile and windrow burning (Logging slash in many cases is piled and windrowed before burning because of problems in igniting and completely burning large fuels (heavy logs) in discontinuous fuel beds. This technique also offers safety for conducting the burn). The objective of piling logging debris before burning is to prolong fire residence time thereby increasing the consumption of large materials. In practice, however, the piling of heavy fuels ends up with mixing large amounts of topsoil and creating a moist pile/windrow interior in which the fuels hardly dry at all and oxygen for complete combustion is lacking. The result is a fire that continues to smolder for days and weeks and creates considerable problems in near-ground air quality.

Prescribed Burning Plans

Although detailed burning prescriptions for tropical forests are not yet available many of the principles and considerations of prescribed burning in industrial pine and eucalypt plantations can be used for planning. A successful prescribed fire is one that is executed safely and is confined to the planned area, burns with the desired intensity, accomplishes the prescribed treatment, and is compatible with resource management objectives. Such planning should be based on the following factors (de Ronde et al. 1990):

Physical and biological characteristics of the site to be treated.
Land and resource management objectives for the site to be treated.
Known relationships between preburn environmental factors, expected fire behavior, and probable fire effects.
The existing art and science of applying fire to a site.
Previous experience from similar treatments on similar sites.
Smoke impact from health and saftey standpoint.

Fire Management Organization

The efficiency of a fire management depends on technical prerequisites (personnel, infrastructure) and on the legal base (definition of responsibilities, issue of a fire policy, legislative aspects, and law enforcement).

Technical Prerequisites

The technical and infrastructural prerequisites for an efficient fire management organization is derived from the phenomena and problems highlighted before. First, it is clear that any fire management concept and organization needs to be based on clear understanding of the impacts of fire and fire management on the forest type to be protected (fire ecology, fire damages, consequences of fire management options, fire management planning, preattack planning). Second, experienced or basically trained personnel must be available to implement fire management measures, ranging from preattack planning, use of prescribed fire, handling of a fire danger rating system, fire detection, etc., to the technical capability to suppress wildfires.

Infrastructural facilities embrace all fire fighting equipment, communication (radio, telephone), transport of personnel and extinguishants, a fire detection network (fire towers, satellite-based observation of fire activities) and weather stations for reporting and forecasting fire weather conditions.

Fire Policy and Legal Aspects

The issue of a fire policy and relevant legislation and regulations are the most important prerequisites for any fire management activities. A fire policy, which would be a basic committment to the fire problem and the definition of a national concept of policies to encounter fire-related problems, needs to embrace the following basic considerations (if not at national level, a policy may also be formulated at the regional or district level):

A general statement on the role and impacts of fire in the most important forests and other vegetation of the country (or management unit).
A general statement regarding how to encounter the negative impacts of fire.
Definition of an overall fire management strategy. Definition of fire management policy in the various geographic regions in accordance with vegetation type, demographics and land uses.
Definition of the role of the population in participating in fire management activities, especially in fire prevention.

A variety of legal aspects needs to be considered for the implementation of a fire policy and for coherent fire management planning, in general e.g.:

Clear definition of landownership and availability of a landownership register.
Development of a landscape plan in which clear definitions are given of the land uses permitted or practiced on a defined area of land.
Regulations concerning construction in forests and wildlands, especially on burned areas.
Clear definition of fire management responsibilities as related to the various types of landownerships and different tasks in fire management, e.g. fire prevention, fire detection, and fire suppression (including coordination and cooperation).
Rehabilitation of burned lands.
Law enforcement.

Collaboration for Developing National, Regional and International Fire Management Programs

Mechanisms of resource sharing between neighboring nations and within regions or even at global scale are required to ensure economically feasible and fast responses in fire management in the tropical world. In South East Asia initiatives have been taken at various levels.

National Programs: The Indonesia Example

In the past two decades the development in Indonesia was faced with manifold fire-generated problems. First, the climatic variability, caused by the El Niño-Southern Oscillation (ENSO), repeatedly brought severe droughts to the archipelago, leading to disastrous wildfire situations. Second, the rapid population increase forces the government to re-settle people from overpopulated islands to less densely populated ones. Most of the transmigrating rural population comes from an ecological and cultural environment in which fire in land use was not common – e.g. people transmigrating from Java to the Kalimantan Provinces. As a consequence, the need to convert rain forest into agricultural systems, associated with a general lack of traditional skill in using fire, increased the risk of wildfires. Third, the regional climate regularly traps the smoke from land-use fires and leads to severe smog problems which do not only affect the immediate environment of the source. Long-lasting inversion layers repeatedly have trapped the smoke from land-use fires and created problems in visibility, traffic safety, and human health.

After the 1991 smoke episode which affected not only Indonesia’s territories but also the neighbouring countries on mainland SE Asia, the Government of Indonesia called for international cooperation for supporting national fire management capabilities. In June 1992 an international meeting was called at Bandung (Indonesia). In this meeting a round table was formed with participation of all Indonesian agencies involved in fire management as well as those international organizations and potential partner nations which offered assistance in developing a fire program.

The conference resulted in a plan for an international concerted action to initiate a “Long-Term Integrated Forest Fire Management Programme” for the country (BAPPENAS 1992; GOLDAMMER 1993). Subsequently, a “National Coordination Team on Land and Forest Fire Management” was formed (BAPEDAL 1996). This team is now coordinating fire management programs at national level in which various international partners are involved, e.g. Germany through the bilateral Integrated Forest Fire Management Project [IFFM] in East Kalimantan (IFFM 1996), the European Union and Japan through their fire management projects in Sumatra, the US Forest Service through fire management training courses, and the Food and Agricultural Organization of the United Nations (FAO) through national fire management planning support.

Regional Co-operation in Fire and Smoke Management

Beginning in 1992, as a consequence of the regional smog problems caused by land-use fires, member states of the Association of South East Asian Nations (ASEAN) created joint activities to encounter problems arising from transboundary haze Pollution. ASEAN workshops held in Balikpapan (1992) and Kuala Lumpur (1995) summarized the problems and urged appropriate initiatives. The ASEAN Conference on “Transboundary Pollution and the Sustainability of Tropical Forests” is one of the first important steps to materialize the conceptual framework proposed during the past years.

Most important in future regional ASEAN-wide cooperation in fire management will be the sharing of resources. The foci will be:

predicting fire hazard and fire effects on ecosystems and atmosphere;
detection, monitoring and evaluating fires; and
sharing fire suppression technologies.

The ASEAN Fire Forum during this meeting will provide important recommendations on joint future actions. The ASEAN region will potentially serve as a pilot region in which resource sharing will be based on the fact that two distinct fire problem seasons exist within the region. While within Indonesia the fire season is mainly during the months of September to November (southern hemisphere dry season), the fire season in monsoon-influenced mainland SE Asia is between January and May. Sharing resources means that hard- and software technologies and required personnel can concentrate on the hemispheric fire problems, and even costly fire suppression equipment, e.g. airplanes, can be used more economically throughout the whole year.

Co-operation in Regional and Global Fire Research Programs

The development of national and regional fire management systems and the development of fire policies and appropriate implementation strategies requires updated inputs by the fire science and technology research community. At national level this is mainly done through universities, government research institutes and other national or bilateral initiatives.

Fire management approaches which aim to address large-scale processes such as regional (e.g. ASEAN-wide) problems of air pollution arising from inappropriate burning must be based on a thorough understanding of these processes. The factors contributing to transboundary haze pollution are manifold. They are rooted in the demography, the socio-economic conditions, and the land-use changes. Furthermore, such large-scale processes must be studied from the point of view of regional climatology and atmospheric chemistry. The role of climate change on the region must also be included.

The role of fire in a changing environment can only be addressed in the context of interdisciplinary studies. The International Geosphere-Biosphere Program (IGBP) provides a scientific-organizational framework for interdisciplinary research programs devoted to explore the fundamental relationships between ecosystems (terrestrial and marine), atmosphere and climate. Within the International Global Atmospheric Chemistry (IGAC) Project, one of several IGBP “Core Projects”, one of the activities of its “Focus 2: Natural Variability and Anthropogenic Perturbations of the Tropical Atmospheric Chemistry” is devoted to investigate the impact of biomass burning on the atmosphere and biosphere (“Biomass Burnig Experiment” [BIBEX]). The goals of the BIBEX research activities are summarized as follows (IGAC 1992; Goldammer 1994):

To characterize the production of chemically and radiatively important gases and aerosols species from biomass burning to the global atmosphere.
To assess the consequences of biomass burning on regional and global atmospheric chemistry and climate.
To determine the short- and long-term effects of fire on post-fire exchanges of trace gases between terrestrial ecosystems and the atmosphere.
To understand the biogeochemical consequences of atmospheric deposition of products of biomass burning.

In the late 1990s it is envisaged to set up a new BIBEX research focus in Southeast Asia, the South East Asia Fire Experiment (SEAFIRE). SEAFIRE will address the regularly occuring smog layers over insular and mainland South East Asia which are originating from a variety of vegetation types:

Slash-and-burn agriculture: Traditional but expanding small-scale clearing of primary forest and secondary vegetation in the perhumid rain forest zone
Other forest conversion fires: Large-scale clearcuts of primary and secondary rain forest vegetation and subsequent slash burning for conversion into other land-use types (e.g. exploitation of mineral, coal and oil resources; conversion of natural vegetation into agricultural plantations and human-made forests)
Regularly occuring fires in seasonally dry deciduous and semideciduous forests (monsoon forests, “savanna” forests) in mainland South Asia
Regularly occuring fires in the submontane and montane coniferous (pine) forests of insular and mainland South Asia
Agricultural residue burning, mainly rice straw, throughout the whole region

SEAFIRE will be designed to investigate this highly complex and diverse fire theater. The aim of a set of experiments will be to identify the magnitude, patterns, quality and impacts of fire on the local terrestrial and regional atmospheric ecology. The SEAFIRE program will be conducted as a set of short-term and directly linked experiments. Infrastructural constraints of observations to be carried out in a variety of countries (Myanmar, Thailand, Kampuchea, Lao, Viet Nam, Malaysia, People’s Republic of China, The Philippines, Indonesia) will require a multi-year approach.

One of the main objectives of SEAFIRE will be to investigate how the zonal circulation along the equator, the Walker Circulation, which set in motion by the tropical convective clouds, is influencing the regional and global distribution of pyrogenic trace gases and aerosols. Th so-called “hot towers” act as cylinders in the global heat engine to pump energy from the tropical sea and land surfaces to great heights before that energy can be exported poleward.

In the “High Phase” deep clouds and rain are centered over the hot spots. In the “Low Phase” the warm waters of the Warm Pool are transported to the eastern Pacific and the circulations are reversed. The sequence of events described above is the evolution of the Southern Oscillation in which the strong trades of the High Phase are replaced by the weak trades of the Low Phase and the El Niño is born. The repercussions of these events in the Pacific are global in extent, triggering droughts and fires in the Ocean Continent, Australia, South America and Africa.

SEAFIRE conducted under High Phase conditions will carry biomass burnig products to the high troposphere and export these products to the global system. Direct and indirect effects to the global system will follow in terms of trace gas chemistry, Greenhouse gases and the effects of aerosols. SEAFIRE conducted under Low Phase conditions will exercise a substantially different effect upon the global syystem. Products of biomass burning are likely to be trapped in the lower atmosphere, have different effects in terms of Greenhouse gas and aerosols than in the High Phase and be connected to differing parts of the global system.

Plans are prepared at present to conduct SEAFIRE as a sub-component of the planned Integrated SARCS/IGBP/IHDP/WCRP Study on Land-use Change in SE Asia “Human Driving Forces of Environmental Change in Southeast Asia and the Implications for Sustainable Development” (in prep.).

International Cooperation in Development of Fire Policies

National and regional fire management and research initatives are the base for the development of international agreements on fire policies and collaboration in fire management. In future this should increasingly include the establishment of mechanisms for sharing information, resources and disaster management.

First steps have been taken to facilitate international collaboration and possibly even international agreements. Within the UN system two bodies have taken the intiative.

In the early 1980s the Economic Commission for Europe (ECE) began to activate international cooperation in fire management. Besides regular seminars, the Timber Section, UN-ECE Trade Division, produces “International Forest Fire News”, an activity of the FAO/ECE Team of Specialists on Forest Fire. This newsletter is distributed worldwide and provides information on national and international fire management and research activities. In the last FAO/ECE/ILO seminar on “Forest, Fire and Global Change” (August 1996, Russian Federation) the delegates developed recomendations for the future role of the UN system in global fire management cooperation (cf. Goldammer and Odintsov, in prep.).

The International Tropical Timber Organization (ITTO) initiated the devlopment of “ITTO Guidelines on the Protection of Tropical Forests Against Fire” (ITTO 1996; in press). The guidelines were produced by an expert panel and are now subject of final revision and release by the ITTC. They provide a base of understanding the beneficial and detrimental use of fire in tropical land-use systems and give appropriate recommendations for fire management.

Concluding Remarks

In this contribution the complexity and ambiguity of phenomena and problems, which are related to the occurrence of fire in tropical forests, wildlands, and land-use systems have been described. The socio-economic and cultural conditions in the tropical forest environment create enormous difficulties in managing fire and smoke. International collaboration is necessary to jointly solve the problems arising from increasing human impacts on the tropical and global environment.

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Tab.1. Global estimates of annual amounts of biomass burning and of the resulting release of carbon to the atmosphere

Burning Source

Biomass burned

Carbon released

tropical

extratropical

total

(Tg dm yr -1)

(Tg yr -1) * Forest

1260

1150

2410

1080

Savanna

3690

–

3690

1660

Biomass fuel

1720

220

1940

880

Charcoal

Agricultural Waste

420

850

380

World Total

7120

1800

8910

4080

* Based on a carbon content of 45% in dry biomass. In the case of charcoal, the rate of burning (based on FAO production statistics) has been multiplied by 4 to account for losses in the production process (Source: Andreae and Goldammer 1992).

Tab.2. Ecological, economic and management aspects of integrated fire management options in various tropical forest and other sub-forest types

Ecological and Economic Aspects of Fire Tropical Moist Forest Tropical Dry and Other Seasonal Forests
(e.g. Tectona grandis, Shorea robusta) Coniferous Forests
(e.g. Pinus spp.) Industrial Plantations
(e.g. Pinus and Eucalyptus spp.) Silvopastoral Systems
(e.g. open pine forests with grazing) Grass Savannas
(e.g. extensively grazed wildlands)

Fire Exclusion

Ecological Impacts High diversity of species, habitats and niches. High stability High diversity of species, habitats and niches. high water retaining and soil protection capability. Replacement of coniferous species by less fire tolerant broadleaved spezies. Pines only on dry shallow and disturbed sites. Overall increase of species diversity. High water retaining and soil protection capability. High risk of uncontrolled high-intensity stand replacement fires. Undesirable increase of species not suitable for grazing purposes. Replacement of grass stratum by succession. Progressive successional development toward brush/tree savannas or forest. Promotion of less fire tolerant species. Economic and Management Implications Heavy disturbances, e.g. clearcuts and skid trails must be avoided Economic wood production difficult because of high diversity of species. increase of non-wood forest products. Economic wood production difficult because of high species diversity. Wood production feasible. Extreme high risk of destruction of plantation by wildfire. only possible if intensively grazed and mechanically cleared. Not feasible.

Un-controlled Wildfires

Ecological Impacts Forest community destroyed or degraded. Pioneer Species favored Selection of fire resistant/tolerant tree species. Opening of forest formation. Retreat of fire sensitive species and favoring of fire resistant pines. Opening of forests. Stand replacement fires. Forest degradation. Stand replacement fires. Uncontrolled selective fire pressure. maintenance of openness. Maintenance of a wildfire climax. Uncontrolled selection of fire adapted plants. Economic and Management Implications High losses involved (bio-diversity, site stability, economics) Species composition and relevant management and marketing opportunities out of control. Tendency of degradation and loss of productivity. Management objectives jeopardized if no efficient fire prevention and control system available. Possible long-term degradation and loss of productivity. Productivity depends on savanna type and other degradation factors involved.

Prescribed Fire

Ecological Impacts Not applicable (only on adjoining fire-prone vegetation) Controlled selection of tree species. Advantageous for stimulation and harvest of selected non-wood forest products. Controlled favoring of desired fire-tolerant species. Reduction of stand-replacement fire risk. Maintenance of desired monostructure of plantations. Reduction of stand-replacement fire risk. Increase of vitality and water supply. Controlled promotion (stimulation) of desired tree and fodder plant species. Controlled promotion of desirable grass/herb layer and tree/brush regeneration. Economic and Management implications Integrated Fire management System requires availability of relevant ecological background knowledge, trained personnel, and infrastructural facilities to prevent and control undesired wildfires and conducting safe prescribed burning operations

Tab.3. Potential objectives for the use of prescribed fire in management of plantations

Objectives Target Desired effects Undesired effects or potential hazards Possible Substitution Wildfire hazard reduction Thinning or post-harvest slash, forest floor (raw humus), aerial fuels, rank understory Reduce potential wildfire intensity, remove surface and ladder fuels, reduce understory stature Stand/tree damage

(crown, bole, or root)

Partial (mechanical treatment/removal by hand, shredding, piling and burning outside of stand, pruning) Site preparation for natural regeneration or planting Forest floor, post harvest slash, undesired vegetation Expose mineral soil (improve germination), increase seedfall Encroachment, sprouting, or germination of undesired plants Partial (herbicides to kill undesired vegetation) Improve accessibility Thinning of post harvest slash, rank understory Improve access for silbivultural operations, esthetics (recreation) Reduction of understory stature Partial (herbicides to kill understory) Increase growth/yield Raw humus layer (forest floor), understory plants Enhance nutrient availability; reduce competition for moisture, sun and nutrients Loss of nutrients (leaching), erosion Fertilization and herbicides Alter plant species composition Weeds and other undesirable vegetation Promote desired species Increase in weed germination/production of undesirable seeds Herbicides Pest management Pests and diseases and their habitats Eliminate spores, eggs, individuals, and breeding material Fire-induced tree stress, increased susceptibility to secondary pests Pesticides Silvopastoral land use Slash; forest floor; mature, unpalatable growth; competing vegetation Create/improve conditions for desired ground cover Mechanical removal of dead fuels and vegetation Improve fire protection Surrounding buffer zone, fuel breaks and fire breaks Reduce spread and intensity of wildfires (outside of stands)

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Fig.1. Types of tropical/subtropical fire regimes as related to ecological and anthropogenic gradients. Exemptions from this generalized scheme such as higher species diversity in certain fire climax communities must be noted

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South East Asia Background

24. November 2017/by GFMCadmin