Forest Fires and Dynamics of Forest Cover - eolss

UNESCO - EOLS

S

SAMPLE C

HAPTER

NATURAL DISASTERS - Forest Fires and Dynamics of Forest Cover - Arkady A. Tishkov

FOREST FIRES AND DYNAMICS OF FOREST COVER Arkady A. Tishkov Institute of Geography, Russian Academia of Sciences, Moscow, Russia Keywords: burns, carbon emission, crown fire, deforestation, forest fore, forest protection service, forest regeneration cycle, landscape fire, pyrogenic successions, pyrophytes, surface fire, taiga. Contents 1. Introduction 2 .Forest and fire 3 .Global and national statistics on forest fires 4 .The fire rotation in forests 5. Fire as instrument of forest ecosystem management 6. What is the impact of fire on forests? 7. Pyrogenic successions of forest vegetation 8. Forest fires in taiga of North Eurasia 9. Forest fires and carbon emission 10. Anti-fire forest protection measures Glossary Bibliography Biographical Sketch To cite this chapter Summary Forest fires are probably the most dangerous form of a landscape fire. Evidence of forest fires has been found in deposits from the Carboniferous period. Forest fires have always occurred naturally, but since Homo sapiens first learned how to use fire, the majority of forest fires have been of anthropogenic origin, approximately in 40 to 90% of total occurrence. “Wild fires” have had a significant effect in determining composition and natural rhythms of forests. According to estimates available each year about 20 million hectares of forest vegetation are affected by fire. In Russia alone the area suffering from fire is estimated asabout 10 million ha (up to 2 million ha per year). The frequency of fires exerts a major influence on the structure and dynamics of forests (especially in regions with long dry seasons). Full recovery after a crown fire can take 100 to 150 years, but the interval between crown fires is likely to be 300 to 400 years, particularly in wet forests—a sufficiently long period to allow recovery. Ground fires are followed by secondary pyrogenic succession as a mechanism of regeneration, and complete recovery takes from 5 to 30 years, or occasionally longer. Information about frequency of fires can be determined from dendrochronogical studies (using data from tree rings). A special ecological group of plants, the pyrophytes, are well represented in the secondary succession after a fire. These plants have adaptations to tolerate ground fires (e.g. very thick bark, seeds with a

©Encyclopedia of Life Support Systems (EOLSS)

UNESCO - EOLS

S

SAMPLE C

HAPTER


very thick coating, small leaves, ready establishment of shoots from burnt wood, effective wind dispersal of seeds, etc.). The global carbon cycle is heavily influenced by the ability of forests to act as a carbon sink, storing carbon within their phytomass, and carbon emission from forest fires is also another important part of the cycle. The mass of carbon emitted to the atmosphere during and after crown fires in the boreal belt of northern Eurasia can be more than 100 to 150 tons per ha. Fire protection and monitoring now uses satellites and space stations (for remote sensing), as well as aircraft control, fire-towers and masts, and special mechanized teams. But fire control is still entirely absent in a large part of eastern Russia (eastern Siberia) and in other countries. 1. Introduction Forest fire is a type of landscape fire, a broad category which also comprise fires of steppe, bog, grassland, and tundra. Forest fires are usually more disastrous than fires in other habitats because of the large volume of plant matter burned and the rapid spread of the fire. In the formal statistics of many countries forest and non-forest fires are not distinguished (e.g. in Spain, Portugal, Greece, etc.), partly because of the nature of the vegetation. National forests in these countries can includes scrubby terrain, e.g. garrigue and maquis, grassland and agricultural land as well as forest. A single forest fire would usually burn other habitats in addition to forest. Nevertheless, from a global perspective, forest fires are regarded as being substantially different from other types of fire, on account of their scale and consequences. Forest fires are mostly of anthropogenic origin—from 40 to 90%. But fire played a decisive role in the development of natural forests even before their occupation by humans. The composition, rhythm of functioning and dynamic succession of forests have, to some extent, been determined by the impact of “wild fire”. This particularly applies to many types of pine woods (Pinus spp.), larch woods (Larix spp.), and oak forests (Quercus spp.). Evidence of forest fires has been found in deposits from the Carboniferous period. Fire has been a determining factor in the process of adaptation of plants; many species are well adapted to survive fire and regenerate shortly after. Such plants represent a special ecological group—the pyrophytes and they can be met in natural ecosystems of all the climatic zones of the Earth, from the tundra to the tropics. They have the following characteristics: • seeds are able to germinate after fire (a good example is Pinus contorta in Florida,

USA); • trees may have a very thick bark which protects the underlying wood from ground

fires (e.g. various species of Pinus, Quercus, and some trees in dry savanna, such as the monkey-bread tree, acacia, etc.);


UNESCO - EOLS

S

SAMPLE C

HAPTER


• the crowns of trees are relatively high, with little understorey, so a ground fire may not develop into a crown fire (characteristic of acacia, eucalyptus and pines, etc.);

• the seeds can have a very thick hard coating, and may only be able to germinate after fire, and

• buds are readily produced from burnt wood and the shoots do well in absence of competition from other plants (most ground vegetation in the postfire period comprises plants with wind-blown seeds, which arrive after the fire and germinate in the bare ground).

2. Forest and fire In 1997, the World Conservation Monitoring Center produced a map showing forest cover on the Earth 8000 years ago. Compared with the contemporary situation, it indicates that since the start of the human expansion on the Earth different continents have irreversibly lost 30-70% of their forests. Furthermore, only 1% of European forests, 20% of Asian forests, and 60% of South American forests can be regarded as pristine (e.g. the primary forests in the North American mountains, the Amazonian basin, Oceanic islands and vast territories, mainly of taiga, in Russia). (See Table 1).

Contemporary forests (CF)

Contemporary pristine forests Region Forests 8000 years ago,

1000 km2 (F) 1000 km2

% of F

1000 km2

% of F

% of CF

Africa 6799 2302 34 527 8 23 Asia 15,132 4275 28 844 6 20 North and Central America 12,656 9453 75 3909 31 41

South America 9736 6800 70 4439 46 65 Europe except Russia 4690 1521 32 14 0.3 1

Russia 11,759 8083 69 3448 29 43 Oceania 1432 929 65 319 22 34

Source: WCMC, Global Biodiversity, 2000

Table 1. Territory of contemporary and preserved pristine forests in the world Fire as a natural factor in principle cannot play a determinative role in the reduction of forest area, but it plays an important contributing role in combination with three major causes of deforestation—logging, mineral extraction and clearance for agriculture. The frequency and number of anthropogenic forest fires increases rapidly in connection with such activities. The contribution of fire to deforestation is higher on the perimeter of forest ecosystems, e.g. on the northern and southern margins of the taiga, and on the upper boundary of forest cover in mountainous areas. For example, a fire is responsible for the 100-300 km wide, relatively deforested tundra belt in northern Eurasia. In this case, the climate and


UNESCO - EOLS

S

SAMPLE C

HAPTER


soils are favorable for forest vegetation but periodically fires set back the growth of trees. They also play a determining role in the expansion of grasslands in zonal ecotones: the “forest-steppe” in Eurasia, “forest-prairie” in North America, “forest-pampas” in South America and “forest-grassland” (or forest-savanna) in Africa, South Asia and Australia. For several millennia, grassland fires made for the purpose of pasture improvement have maintained well defined grassland "islands" within forests, by diverting natural processes. Fire on its own cannot replace forest with non-forest vegetation, particularly in transitional situations of environmental gradient, e.g. in dry habitats, patches of land with a high water table, and so on. Destruction of forests by fire in wetlands may give rise to waterlogging and peat formation, but trees will return in the absence of further fire. Fires in dry sandy and stony areas in temperate climates lead to formation of heathland or dry acid grassland, both of which are susceptible to frequent fires, particularly where there is little or no grazing. In both cases, the frequency of fire (the “cycle of fire”) can be considered as a major factor of deforestation but not a fire itself. A general understanding of forest fire coverage can be obtained from OECD data. This shows the trends in areas of burnt woodland in selected countries representing different natural zones (see Table 2).

Country 1980

1985 1990 1991 1992 1993 1994 1995 1996 1997

Canada 4.78

0.76 0.93 1.58 0.87 1.97 6.29 6.57 1.88 0.50

Russia 0.17

- 1.38 0.68 0.69 0.75 0.54 0.36 1.85 0.73

USA 1.25

2.13 2.20 1.30 1.28 1.83 1.65 0.79 2.45 1.57

Mexico 0.11

0.15 0.10 0.27 0.05 0.24 0.14 0.31 0.49 0.11

Greece 0.03

0.10 0.03 0.02 0.06 0.05 0.05 0.02 0.02 0.03

Italy 0.05

0.08 0.10 0.02 0.04 0.11 0.04 0.02 0.02 0.05

Spain 0.26

0.49 0.20 0.26 0.11 0.10 0.44 0.14 0.06 0.09

Turkey 0.01

0.03 0.01 0.01 0.02 0.01 0.02 0.01 0.02 0.01

France 0.02

0.06 0.07 0.01 0.02 0.02 0.03 0.02 0.01 0.02

Source: OECD (1999)

Table 2. The dynamics of forest fires during 1980 to 1997 in selected countries of Europe and North America,

3. Global and national statistics of forest fires At the international conference “Fire and Environment” of 1992 a decision had been made to establish the Global Vegetation Fire Information System (GVFIS), providing a technical basis for a future Global Fire Monitoring Center. At present, these actions are


UNESCO - EOLS

S

SAMPLE C

HAPTER


integrated into a project called “Global Vegetation Fire Inventory”. Previously, more or less complete statistics on forest fires had been accumulated by the European Economic Commission (EEC). This had included data on fires in the USA and Canada (EEC/FAO, 1993). In China, statistics on fires are compiled by the Ministry of Forestry. In its reports since 1949, 4660 fires have been recorded with an average affected area of 1 million ha (10,000 km2) and 105 casualties, each year. The economic losses caused by fires are estimated as US$ 125,000,000 annually, but there is a lot of uncertainty about the data. The FAO experience of fire statistics collection (FAO Global Wildland Fire Statistics; FAO, 1992) confirmed a distinct lack of data and their contradictory interpretation. Efforts to use this data in global biosphere models of carbon cycling and climate change, and for comparative international studies, turned out to be erroneous. The relevant chapters in the reports of the World Resources Institute (World Resources: A Guide to the Global Environment, 1998-1999) do not include this data. The statistics on forest fires for the last 20 years can be found in the annual reports of OECD (OECD Environmental Data, 1999), based on informational support from GRID Arendal UNEP. A few countries have scientific centers carrying out intensive collection of fire statistics. Mention should be made of the Fire Research Group of the Max Planck Institute for Chemistry in Germany. In Russia, corresponding units have been created in the International Forest Institute (Moscow) and the Institute of Forests and Timber (Krasnoyarsk) of the Russian Academy of Sciences. In the latter, very intensive studies have been recently started aimed at estimation of carbon emissions caused by forest fires, for carbon credit estimations. These studies have been also performed within the framework of such international organizations, programmes and projects as: • International Geosphere-Biosphere Programme (IGBP) and its projects: Global

Emission Inventory Activity, International Global Atmospheric Chemistry, Biomass Burning Experiment, etc.

• The International Boreal Forest Research Association, Fire Working Group; • The EEC/FAO Team of Specialists on Forest Fire. 4. The fire rotation in forests Despite predictive measures, strict control and forest monitoring in Eurasia and other continents, forests fires occur every year. Experts estimate that the average area of vegetation affected by fire each year exceeds 20 million ha. In Russia alone the area burnt is estimated at 10 million ha, with substantial damage to natural ecosystems and economy. An unprecedented forest fire, in terms of dimension and damage, occurred in 1997 in Brazil when the El Nino effect gave rise to a fire with a perimeter of 1600 km. But fires of such scale do not occur very often. As a rule, fires in separate parts of a forest occur with a distinct periodicity. The frequency of fires (and the fire cycle) is a determining factor in the composition and dynamics of forest vegetation. On one hand, the frequency of fires affects the pyrogenic


UNESCO - EOLS

S

SAMPLE C

HAPTER


vegetation succession, but on the other, the altered composition of the vegetation changes frequency of fires. During the interval between fires, the vegetation is reconstituted and some quantity of combustible matter is accumulated, ready for a new fire. The consequences of this cycle can give rise to catastrophic consequences: accumulation of excess organic material increases the combustion potential for a future fire; an ordinary fire finds an additional stock of combustible material, temperatures rise and the impacts become still more serious (e.g. degradation of the entire wood content, burning out of soil organic matter, and so on). Instead of normal secondary pyrogenic succession (including regeneration of vegetation on undamaged soil through regrowth of plants and germination of dormant seed), it results in a primary succession, requiring hundreds of years for soil and forest development. After a crown fire, the period of recovery of a mature forest can be 100 to 150 years, depending on the species. The probability of natural recurrence of fire within boundaries of a forest landscape, encompassing all elements of a meso-relief, is no more than once in every 300 to 400 years. In cases of ground fires, the period required for recovery of the vegetation by secondary pyrogenic succession, lasts for 5 to 30 years or longer , depending on the vegetation type. In forest savanna natural burns occur periodically once every few years. In the boreal coniferous forests of Eurasia human settlement within the forested territories is the main reason for the growing frequency of fires. According to the results of dendrochronological studies, the period between fires is about 30 years in intensively used pine forests of the central taiga, while in remote larch forests it is 80 to 90 years. Economic activity aggravates the frequency of fires by a factor of 2 to 3, but at the same time, it facilitates fire control. As a result, in developed areas, the frequency of fires is high, but the area affected and the scale of damage is moderate. 5. Fire as an instrument of forest ecosystem management The fire is a bad host but can be a good servant (a proverb) Natural forest fires (e.g. a result of lightning or intensive volcanic activity) have been of regular occurrence throughout all periods—historic and prehistoric. But since Homo sapiens first learned how to use fire, most forest fires have been of anthropogenic origin. Fire was an instrument of hunting at early stage in the evolution of primitive man, and further on it was used for clearing land for agriculture. It is very likely that such fires often went out of control. There is a widely known ancient system of agriculture in forest zones known as “slash and burn”. This involves felling of trees without their removal, retaining the wood for drying over one or two years, burning out the land, clearance and plowing. It may then be used as arable land for a period of 5 to 7 years (unless it is exhausted before that) and finally it is abandoned, or used for pasture or haymaking. This pattern of agriculture was typical for the whole of Europe, and most of Asia, Africa and America. As a result of the uneven introduction of this burning technology, very large areas of forested land in lowlands and foothills were brought into agricultural use, as is readily revealed by study of their soil profile. At a depth of 7-20


UNESCO - EOLS

S

SAMPLE C

HAPTER


cm one can often find a “plow layer” and pieces of charcoal which had been plowed in. They contain a lot of information in respect to past agricultural patterns and transformation of forest cover into a mosaic or scattered fragments resulted from such practices. In Europe, forests dominated by oak and other broad-leaved forests which had been intensively cleared from the tenth to twelfth centuries, were the first "sacrifices" of the cutting-burning technology. As the period of exploitation of the cleared land was very short (no longer than 15 years), one hectare of arable land was counterbalanced by around 10 to 12 ha of forest at different stages of regeneration. However, the period of forest regeneration after burning and cropping would have been longer 150 years, so the area of mature forest was steadily reduced. In certain areas, particularly those with a dry climate, people intensively burnt the forests to create pasture or hay meadows. The famous European heaths, which were mainly used for sheep grazing, appeared as a result of this practice. In certain regions of the Russian European North, in the Urals and in Western Siberia, the inhabitants traditionally have been using controlled ground fires (grassland fires) for melioration of lichen forest pastures, to improve grazing for reindeers. This practice remained unchanged until recent years. Mention must be also made of a tradition to use fire for burning the vegetation of low strata in certain types of pine-forests in western Siberia to promote the harvest of forest berries, for example cowberry Vaccinium vitis-ideae, and burning vegetation to increase value of hunting grounds (and the density of red-legged partridge). Fire is also used by some foresters in order to raise a forest grade, and to increase a portion of valuable species in their structure. In eastern and south-eastern forests of USA, particularly in national parks at present time, there is a practice of increasing the resilience of longleaf pine Pinus palustris by seasonal burning. Fire management is routine practice in protected forests in the national parks of the USA and Canada. It helps prevention of surplus accumulation of combustible vegetation matter. In some parks and natural reserves fire helps to control exotic species, including various trees. 6. What is the impact of fire on forests? Fire can occur in a forest only when three conditions are satisfied at the same time: • accumulation of sufficient volume of unevenly distributed inflammable vegetation

matter, • meteorological conditions favorable for burning (dry air, wind, lack of

precipitation), and • source of ignition in close proximity (dry lightning, volcano eruption streams,

accidental explosions, non-extinguished bon-fires, smoldering of a cartridge case after a hunter’s shot, a spark produced by working machines, focusing of solar energy by broken glass, etc.).


UNESCO - EOLS

S

SAMPLE C

HAPTER


Precipitation, or rather its absence, provides conditions for spread of fire over a large area, and can play a determinative role in the origin and spread of forest fires. In the boreal forests of Eurasia these periods usually take place in spring and summer, and on the Pacific coast, in autumn. From time to time in particularly droughty years, forests may be susceptible to fires all the year round. The main danger period in northern coniferous forests is the end of autumn, when the forest litter and moss-lichen cover has dried after snow melting, but fresh green growth is still absent. Forest litter, comprising the dead parts of different plants has different susceptibility to burning. Some of principle tree species in Europe have the following distribution of inflammability (as shown by certain outstanding botanists): aspen (Populus tremula) birch (Betula pendula) pine (Pinus sylvestris) spruce (Pices abies)- larch (Larix spp). Mosses and lichens do not have a system to uptake water from the soil or to regulate their water regime, so they are characterised by exceptional hygroscopicity—they readily absorb water and rapidly wither in dry weather. Forbs and dwarf shrubs do not wither as much intensively as spore-bearing plants and their sward may impede the spread of fire, but there is a lot of variety between species. Heather Calluna vulgaris and ledum Ledum palustris are highly inflammable, while cowberry Vaccinium vitis-ideae and the crowberry Empetrum hermaphroditum are not . Bog billberry (Vaccinium uliginosum), .kassandra Hamaedaphne calicullata and bearberry Arctostaphylos uva-ursi are also characterized by low inflammability. Dry herbage has a high susceptibility to inflammability, particularly short-ear Calamagrostis spp., club-moss Lycopodium spp., wintergreen Pyrola spp., and ferns such as Pteridium aqulinum and Dryopteris spp. Tall herbage of humid forests, e.g. Filipendula ulmaria, Aconitum spp., Millium effusum, and Festuca gigantean, etc. do not burn readily. The most inflammable trees are the conifers, particularly the pines Pinus pumila, P. sylvestris and P. sibirica. Spruce Picea abies, firs Abies spp. and deciduous species are less inflammable. The hierarchy of inflammability is as follows:Pinus pumila Pinus sylvestris s.l. Pinus sibirica, P. koraiensis Abies sibirica, Picea abies, Abies spp. Betula spp. Populus tremula Alnus spp. Populus balsamifera, Populus nigra Salix spp. Sorbus aucuparia. The most inflammable of the shrubs is juniper Juniperus sp., and the least inflammable are briar Rosa sp., honeysuckle Lonicera spp. and, in particular, Alnus fruticosa. Ground fires which in dry windy weather may spread quickly through a forest, affect only the lower strata—moss and lichen, grass and dwarf shrubs (sometimes bushes and coppice). As a rule, the litter and roots of trees are never damaged, but in rare case of combustion of litter and fallen dead wood, surface roots can be damaged. In boreal forests the most affected species is spruce, as its roots are exposed (unlike those of pine) in the surface layer of soil. This species demonstrates different strategies of growth and adaptations to fire impacts.


UNESCO - EOLS

S

SAMPLE C

HAPTER


Crown fires cause either entire or partial destruction of trees. When driven by a high wind, a crown fire can remain in the upper strata and cover long distances through the canopy. Temperatures can be very high, even on the ground, and as a result the long-accumulated organic matter is burnt over vast territories, passive animals are killed, and the soil cover is demolished. The impact of such a fire is more serious than heavy logging, which does not remove all the trees, and causes only partial damage to the ground layer and soil cover. The combustion processes produce large quantities of carbon oxides, nitrogen, sulfur and ash containing readily soluble compounds. As a result, the forest ecosystem loses huge volumes of chemical elements important as the mineral nutrition of plants (through discharge of gaseous components, washing out, deflation, etc.). But improved supply of nutrient substances stimulates intensive regeneration of vegetation in burnt woodland through stimulation of microbiological activity of soils, development of nitrification processes, and so on. It should be emphasized that the initial opportunities for re-establishment of vegetation in burnt forest are better than in primary substrata on mountains and volcanic deposits. Intensive colonization of burnt forest is limited by size and distance (seeds and propagules cannot readily reach areas of burnt forest far from the edges), and more often colonization is impeded by water logging. The absence of trees with their powerful transpiration processes changes the hydrological regime and causes upsurge of the underground water level. In areas with permafrost the regeneration processes after forest fires can be impeded by thermokarst development, caused by repeated freezing and thawing (solifluction, thermoerosion, bogging, etc.) and creation of an uneven surface. 7. Pyrogenic successions of forest vegetation Pyrophytous forest plants contribute heavily to the early stages of re-colonization, indicating fire in the recent past. In the case of a ground fire with preservation of the canopy, the regeneration encompasses two processes: replacement of the herbage and bushes, and regeneration of moss and lichen cover. This pattern is relatively simple. For example, in dry pine forest immediately after a fire the burnt vegetation is replaced with moss cover composed of Polytrichum juniperinum, P. piliferum, Ceratodon purpureum, and Pohlia spp. These mosses impede the regeneration of lichens. However, in humid periods spread of reindeer lichen, e.g. Cladonia glacilis and C. deformis can occur. These are referred to as the so-called “burnt wood companions”. They are gradually replaced by the lichens Cladina amaurocraea, C. uncinalis, C. sylvatica, аnd later C. rangiferina and others. The scheme of boreal forests succession (Picea abies-climax) is presented in Table 3.

Steps Weeds and

mosses-pyrophytes

Meadow Secondary forest Mixed forest

Climax spruce forests

Time (years) 2-3 5-10 10-20 20-40 after 100-150


UNESCO - EOLS

S

SAMPLE C

HAPTER


Key species

of trees

Betula,

Populus\ Pinus

Betula+Picea\ Pinus+Picea Picea abies

Key species

of grasses

and dwarf shrubs

Calamagrostis, Chamaenerion

Lerchenfeldia, Poa,

Calamagrostis, Solidago

Calluna, Vaccinium vitis-ideae,

V. myrtillus, Pteridium

Vaccinium spp.,

Pteridium, Equisetum,

Luzula

Oxalis, Pyrola,

Dryopteris,

Key species

of mosses

and lichens

Polytrichum, Funaria,

Ceratodon, Marchantia

Polytrichum, Brachithecium

Dicranum, Cladina, Cladonia

Pleurozium, Dicranum

Pleurozium, Hylocomium,

Dicranum

Table 3. The steps of post-fire boreal forest succession, their duration and key species

8. Forest fires in boreal forests of North Eurasia It is a very difficult problem to obtain complete information on fires in the taiga zone, particularly due to the lack of an aircraft survey over vast territories of Siberia and the Far East. For example, according to different estimates the total area of forests affected by fire varies between 2.0 and 5.5 million ha to 10.0 and 12.0 million ha. The official reports present contradictory information, even with respect to registered fires only. On fully protected forest territory (two thirds of the national forest lands) each year, between 10 000 and 35 000 forest fires are registered. The total area of affected forests equals to 16 000 000 ha (and additionally 12 400 000 ha of unprotected territories). The year 1998 is illustrative in this respect for Russia. It was remarkable for an unusually early spring with high temperatures registered and snow melt starting a month earlier than normal (in March). Fires occurred from April to November. In total, 29 970 forest fires were registered, covering 4 268 800 ha of forested and 1 070 900 ha of unforested land. This was the worst for the last 25 years. In spring, the most intensive fires were in Buryatya, Yakutya, Chitinskaya, Tomskaya, and Irkutskaya oblasts. In summer, the highest fire threat situation was registered in the northern Caucasus, in North Osetia, Dagestan, Krasnodarskyi and Stavropolkyi region, and also in Voronezskaya and Ryazanskaya oblasts. A fire in Chabarovskyi region was of disastrous character, where 1500 ha was burnt, and on Sakhalin Island a disastrous situation was monitored in both the summer and autumn of 1998 with the use of satellite monitoring facilities of the technological engineering center “SkanEx” through offices of Greenpeace. The data obtained were used to compare official reporting with actual situation estimated from the satellite monitoring data, and successive scanning.


UNESCO - EOLS

S

SAMPLE C

HAPTER


The official reports indicated the affected area of Sakhalin forests to be 80 800 ha, but the Greenpeace estimation was 270 000 ha (and 420º000 ha together with the unforested territory). The most affected areas were in the vicinity of oil- and gas-exploration projects and massive fish poaching activities in rivers. The most disastrous ever, however, had been in 1954 when the land affected by fire on Sakhalin reached 454 000 ha! Underestimation of damage by official sources constrains possibilities of providing additional assistance to the fire control activity, and aggravates the disastrous situation. 9. The forest fires and carbon emissions The global carbon cycle is determined to a certain extent by the capacity of terrestrial ecosystems to connect (tie up) carbon in their phytomass, and it also includes an important component of carbon emission from forest fires. Its contribution to the global cycle is provided by two processes: emission of carbon into the atmosphere as a direct result of burning, and subsequent emission of carbon into the atmosphere as a result of destruction of the organic material of damaged plants. The volume of carbon released into the atmosphere during a fire depends on quantity of burning organic matter. This estimation is difficult to obtain on account of differences in species composition, their age, stocks of dead trees and slash. However estimations based on phytomass stock data allow determination of the volume of burning organic matter in the case of crown and ground fires (see Table 4).

Volume of burnt matter, t/ha

Combustible material Total

stock, t/ha per year

under crown

fire

under ground fire

Aerial: needles, leaves, small branches, epiphytes and lichens 4-12 7 -

Ground: plant material over the soil cover (mosses, lichens, grasses, herbs, dwarf shrubs), fresh leaf-fall, thickets

2-15 5 5

Ground: forest litter, upper soil layer 5-150 12 5 Ground: fallen timber (slash, dead timber, logs) 2-20 6 2

Total 30 12 Source : Bazilevich, Tishkov (1986).

Table 4. Composition of the surface living and dead vegetation matter in boreal forests

of Eurasia All the accumulated and growing stocks of vegetation represent material ready for combustion. According to Basilevich and Tishkov (1986) the total stock of phytomass in the world’s forests varies from 40 (in forest-tundra and open woodland) to more than 2000 t/ha. A severe fire can penetrate deep into soils along dead and even living roots. Estimations of the quantity of actual combustible material available are therefore complicated, but they are usually based on surface vegetation matter—both living (the


UNESCO - EOLS

S

SAMPLE C

HAPTER


bole, branches and leaves of trees and bushes, dwarf shrubs, herbage, mosses and lichens) and dead (dead trees and branches, slash, and litter). The main component in the composition of the forest surface living and dead vegetation matter is living timber, but occasionally, dead wood and litter determine the major component (see Table 5). A substantial portion of the phytomass affected by fire is killed and involved into the cycle of destruction (see Table 5). According to researches of Russian specialists, about 85-90% of phytomass is killed and destroyed by a crown fire. In a ground fire this proportion is much less—5 to 50% for larch, 15 to 65% for pine, 25 to 85% for spruce and 5 to 60% for birch. Differences in the geographic distribution of these figures are negligible and they most closely correlate with climate, particularly with its continentality, which increases inflammability and temperature of the fire.

Crown fire Ground fire Region Mass of trees

prior to fire Mass of

burned trees Mass of trees prior to fire

Mass of burned trees

European Yralskyi 66.9 60.2 69.2 15.7

Western Siberia 64.4 58.0 67.6 15.2

Eastern Siberia 81.1 73.0 76.6 17.2

Far East 56.7 51.0 56.8 12.8

Table 5. The mass of material burned in crown and ground fires in boreal forests in northern Eurasia, t/ha

10. Anti-fire forest protection measures In spite of a certain role of fire as a natural factor in ecosystem dynamics, many countries have organized special services or similar units for anti-fire forest protection. Firstly, fires may result in casualties and damage or destruction of property. Second, forest fires are regarded as natural disasters, destroying vast areas of flora, fauna and their habitats, including unique ecosystems, representing the natural heritage of the planet (the witness is the extent of forest degradation in National Parks in USA and nature reserves in Russia). Third, fire demolishes a valuable natural resource—the timber, which has a regeneration cycle not shorter than 60 to 100 years.As a result the fire “harvest” deprives people of construction materials, chemical raw material and fuel. The most difficult task in forest protection is timely information to give a chance of immediate location of a fire and hence its effective control. Otherwise fire may spread over a large area and get out of control.The next type of activity is connected with anticipatory measures. It includes stewardship felling, formation of special anti-fire mineral barriers, restriction of forest visiting in dry periods, dissemination of information, etc.


UNESCO - EOLS

S

SAMPLE C

HAPTER


The most costly and technically sophisticated type of activity is monitoring, comprising both active and passive measures. Active measures include space and aircraft monitoring and car and foot patrols of forests, and observation from special towers and masts. Passive measures include the registration and monitoring of fires and assessment of their consequences, e.g. the severity and size of affected area. For example, in Russia the territory covered by active fire protection reaches 750 000 000 ha, and that with aircraft support, 700 000 000 ha. Aircraft control of forest protection services comprises 64% of the national forest lands. Any control of fires is entirely absent on a third of the territory of Russia (mainly in eastern Siberia). For the last twenty years, the controlled territory has been increased only by 2%. At the same time, the space services are more involved into the monitoring activity, including the use of orbital stations and satellites. Remote control is achieved through a specially designed survey system, using different scales. Russia now has experience of using the Resource satellites, which permit receiving 2 to 4 channels of spectrazonal photos with a resolution of 35 to 150 m and a coverage zone of up to 600 km. More detailed screening can be achieved with use of the infrared range. Fire control through the NOAA series of satellites uses photos of 1100 x 1100 m resolution, with a coverage zone up to 2000 km from east to west. Deciphering of the data is performed automatically and interpreted into a GIS (Geographic Information System) with classification of the fire sources according to their intensity—from 1st (portions in crown fires) up to 5th (dying fire, and the next stage, burnt wood). Over the territory of active fire protection in Russia there are 323 functioning aircraft units, organized from 23 aircraft bases. For the control and prevention of the spread of fire, about 450 airplanes are leased including the famous “flying boat” VE-12R, which is capable of transporting 6 tons of water, a plane-tanker altered on the basis of IL-62 with a capacity 62 tons of water, and MI-8 MTV helicopters. Also involved in forest protection are 24 mechanized teams and more than 2000 fire-chemical stations. Surveillance of controlled forests is performed from 1200 fire-control towers and masts. Glossary Burns: Forest areas after fire impact. Unnatural (clearing) and natural

burns are distinguished. Carbon emission (in the forest fire context):

Enhanced emission of carbon from a forest (in different forms – CO2, CO), both during and after a fire.

Crown fire: A type of forest fire spreading at a high level of a forest, i.e. through the crowns, trunks, young trees, bushes.

Fire rotation: The real period between crown or surface fires on forest plots estimated by monitoring or unidirectional methods.

Pyrogenic The form of secondary succession of ecosystems which occurs


UNESCO - EOLS

S

SAMPLE C

HAPTER


succession: after fire. Pyrophytes: Plants adapted to tolerate the impact of fire. These plants have

special adaptations to fire and environmental conditions after fire, e.g. chemical content of soil, etc).

Ground fire: The type of forest fire spreading at ground and surface levels of a forest, i.e. through the shrubs, grass, mosses, lichens, litter, and dead parts of forest plants.

Bibliography

Bazilivich N.I., Grebentchikov O.I., Tishkov A.A. Geographical regularities of ecosystem structure and functioning. Ed.: Isakov Yu. A. Moscow, Nauka, 1986, 297 p. [Monograph about different geographical aspects of productivity, biological turnover and distribution of zonal ecosystems in former USSR].

Biodiversity conservation in Russian Federation. The First National Report. Moscow: The State Committee of Russian Federation on environment protection, 1997, 170 p. [Report on biodiversity conservation actions in Russia, including forest protection data (except text - 30 maps, list of Red Book of Russian Federation a.o.].

Global biodiversity. Earth’s living resources in the 21st century. Ed.: B. Groombridge and M. D. Jenkins. World Conservation Monitoring Centre. Cambridge, 2000, 246 p. [Last guide on problems of global biodiversity, including modern information on world forests distribution].

Isaev A.S., Korovin A.S., Sykhih V.I., Titov S.P., Utkin A.I., Golub A.A., Zamolodchikov D.G., Prjazhnikov A.A. The ecological problems of dioxide adsorbing under forest restoration and forest plantation in Russia (Analitical review). Ed.: Alexei Jablokov. Moscow, Centre of ecological policy, 1995, 155 p. [Analytical review on problems of carbon emission and accumulation in Russian forests in “carbon credit” context].

Isaev A.S., Korovin A.S. The carbon in forests of North Eurasia. In: Carbon turnover on territory of Russia. Ed.: G. A. Zavarzin Moscow: Ministry of science and technologies of Russian Federation, 1999, p.63-96. [Article about carbon accumulation by Russian forests, including problems of role forests fires in this processes].

Kessel S.R. Gradient modeling: Resources and fire management. Springer Verlag, NewYork, 1979, 433 p. [Review of gradient modeling of forest successions for ecological management, including experience of post fires succession modeling in USA national parks].

World Resources. A Guide to the Global Environment, 1998-1999. Environmental Change and Human Heals. Oxford University Press: N.-Y, Oxford, 1998, 369 p. [Guide on modern environmental statistic information from different countries; modern data about forest fires and burning areas].

Biographical Sketch Arkady Alexanrovich. Tishkov (born in 1950) is one of leaders in the present-day biogeography and nature conservation. Graduated from the biological faculty of Moscow State University in 1973. he has been working in the Institute of Geography, Russian Academy of Sciences. Since 1990, he has become Head of Laboratory and a professor at the International Independent University of Ecology and Politology. In 1979, he obtained a scientific degree for his thesis entitled is “Bryophyte Communities in Tundra and Taiga Ecosystems”, and in 1994 he was awarded Doctor of Sciences and Professor of Geography (his second thesis was entitled “Geographical Regularities of Natural and Anthropogenic Successions”. He has participated in many expeditions, e.g. the Taimyr peninsula, Magadan region, Kola peninsula, Spitsbergen (Norway), Uzbekistan, Ukraine, Hymalayas (China), and other regions. He is scientific secretary of the editorial office of "Proceeding of Russian Academy of Sciences: Geographical Series", editor of “Problems of Regional Ecology”, secretary of the section "Flora and Fauna Conservation" in the Higher Ecological Council under the State Parliament of Russia, a member of the Nature Protected Areas Commission of the Russian Academy of Sciences, a member of the


UNESCO - EOLS

S

SAMPLE C

HAPTER


Biogeography Commission of the International Geographical Union, and coordinator and Deputy Chief Editor of “First National Report: Biodiversity Conservation in Russia”. In recent years, he has supervised 12 PhD students in geography and published over 350 research papers and monographs including: Geographical regularities of structure and functioning of ecosystems (1986); Geographical regularities of ecosystem dynamics (1986); The basis of modern biogeography (1993,1995); Ecological restoration of disturbed areas in the North (1996); and The future of steppes (1997). His research interests are geography of biodiversity, succession, ecological restoration, and biodiversity conservation. Current research projects for which he is acting as leader include: climatic fluctuations and successions of zonal vegetation (1993-1994), changes of biodiversity after invasions of exotic species (1993-1995), small watershed vegetation dynamics in southern taiga (1993-1994), biogeographical effects of alien species invasions (1995-1997), and biodiversity conservation, a GEF Project (1996-2001). To cite this chapter Arkady A. Tishkov, (2004), FOREST FIRES AND DYNAMICS OF FOREST COVER, in Natural Disasters, [Ed. Vladimir Mikhailovich Kotlyakov], in Encyclopedia of Life Support Systems (EOLSS), Developed under the Auspices of the UNESCO, Eolss Publishers, Oxford ,UK, [http://www.eolss.net]


Forest Fires and Dynamics of Forest Cover - eolss

Documents

Transcript of Forest Fires and Dynamics of Forest Cover - eolss