lnstitut National de la Recherche Agronomique

s 1 .09-00Comite Silva Medit erranea

Atelier lnternationalsur le Br0lage ContrOle

lnternationa! Workshopon Prescribed Burning

Avignon France11 - 18 Mars 1988

Expos6s, Proceedings

Conseil Regional de

Provence-Alpes-COte d' Azur

Conseil G6n6ral

de Vaucluse

i.N.R.A. Station de Sylviculture M6diterran6enne

Avenue Antonio Vivaldi 84000 Avignon - France

IUFRO

2t

Limitations and Needs in Maintaining or Restoring Prescribed Fire Regimes inNatural Forest Lands and Plantations

Johann G. GOLDAMMER

Department of ForestryFreiburg UniversityFreiburg - B.R.D.

,)

SUMMARY

The developments of a variety of degrading forest ecosystems in the lowerIatitudes are influenc.ed by no.n-planned anthroflogenetic fire iegimes. Short returninterval fires are a charabteristic feature in mainiaining a fire ?limax (subclimax)stage of vegetation development. When converting nori-planned fire rdsimes int6prescribed fire regimes, the negative impacts -ot firb on the site" and thesurrounding environment have to 6e consideied.The main problem connected with fire are invasion of undesirable endemic/exoticspecies, interactions with pests, erosion and air p-ollution. Contemporary planningof prescribed fire regimeS requires the temporil and sparial straiificatioh of tnEfire environment and the searCh for alternatives to presciibed burning.

RESUME

L'extension en zone tropicale d'6.cosystdme forestiers d6grad6s est en relation avecIes feux non planifi6s li6s aux activit6s humaines.Une..grande frequence des feux entraine Ie d6veloppement d'une v6g6tation endquilibre avec le feu.Lorsque Les jeux contro.l6s remplacent les feux non.planifi€s, Ies aspects n6gatifs defimpact du feu sur le site et soi environnement doivent €tre pris ei consioEration.Les. princip?gx .probldmes Ii6s d l'emploi du feu sont l'irivasion d'ind6sirablesfs.Pdcgs end6miques ou exotiques ef les int6ractions avec Ies d6piadations,I'erosion et la pollution atmosph€rique.Une planification moderne de-s feux-contr6lds exige la stratification du milieu dansle temps et dans l'espace, et Ia recherche de sdlutions de rechange au Uiniagecont16l6.

l.INTRODUCTION

By the end of the 20th century it becomes more and more visible that the world,sforests of all vegetation zones are undergoing a major change. lnng-range andshort-range transport of industrial emissions are causing se"vere pr5blerfis anddamages to the tbrrestrial and aquatic ecoSystems of the" northerri circumpolar,boreal and temperate zones.In the mediterranepn^ subtropical^and tropical regions (the "South") the stabilityand .sustainment of forests and forestry is highl! enda'ngered by tfie increasingamount of fires in forests and wildlands which Irsfollowin"g in the'wake of alteretand expanding- land-use- systems. The interactions between degrading forestecosystems .an.d the hydrosphere-atmosphere on global climate and-"globalchange" are being recognized.

22

By succ.essively better understanding of gtoQ4 ecolo-gical processes it is possiblethat. policief of contemporary forest and wildland fiie minagement may face afundamental crisis: the shift from the fire control policy towa-rds Integraled FireManagement seems to swing back due to environmehtal i:onstraints.Are tfe

, ecologically based concepts of Integrated Fire management and

prescribed burning becoming questibnable at tEe very moment ii which theEuropean foresters begin to reflect about restoring fiie into forest ecosystemmanagement ?

A hypothetical. developmeTt ^.of forest Bcosystem management and firemeTtagqggnt policy-as shown in figure 1 may result into a post-riodern fire controlpolicy. Tlp pqp"r does not intend to proof whether this hypothesis is realistic ornot. A critical look, however, is- given to the limits and needs-of prescribed burningand prescribed fire regimes and the alternatives to prescribed buining.

2. NATURALAND ANTHROPOGENETIC FIRE REGIMESAND PRESCRIBED BURNING

The kind of fire history that led to the development ofsummarized as its firq legime (HEINSELMAN 1981).According to KILGORE (1981) the characreristic'featuressuch factors as fire frequency and intensity (HEINSELMAN

an ecosystem can be

of a fire regime are1978, SANDO 1978),

!g$^?n (GILL 1973), pauern (KEELEY'1979) and deprh1e78).

of burn (METHVEN

KILC.ORE J19-Sl)^f:gposed a modification of the fire regimes described byHEINSELMAN (1978) for use in forests and scrublands of the-Western U.S.A. Hi:distinguished six kinds of fire regimes based on the impact of fire frequenry andintensity on the vegetative structure :* frequent, low-intensity surface fire, 1, to 25 year return intervals,* infrequent, low-intensity surface fires, more than 25 year return intervals,* infrequent, high-intensity surface fires, more than 25'year return intervals,* short return interval, stand-replacement fires, 25 to 100 year return intervals,* variable regime_:Aequ^ent. Iow-intensiry surface fires- and Iong return standreplacement fires 100 to 300 year return intervals,] u.ry long return interval, stand replacement fires, more than 300 year returnintervals).

GOLDAMMER (1986) designed a model of seven types of fire regimes intropical/subtropicalvegetation.-Tle fire-regimes are charaiterizedby the d'egree ofdisturbance (degrad.ation) and -site stabiliry, under a generalized-framew"ork ofanthropogenetic and ecological factors (figure 2).When.developing a fire management poJicy or a prescribed burning program it isessential to define- the ecological and anthropogenetic charactEristic-s of theprevailing or desired fire regime.BARNEY (1975) defined fire management as "the integratins of fire relatedbiological,

'ecological, physical anE technological iriformaiion into landmanagement to meet desired_ objectives". BORROW (1977) proposed that "firemanafement activities shogld be loverned by' resource managemerit objectives andboth beneficial and damaging aspects of fire should be considered".

The most crucial question in developing a "prescribed fire regime" is whether thefire regime is- likely to be a natural one or an answer -to anthropogeneticdisturbance of vegetation and the problems created by man-made - forestecosystems (plantations).

23

Intensive forest managem_e_nt will not pe.rmit to restore natural fire regimes such asthe tvpes 3 to 6 of the Heinselman-Kilgore definition ; the same iefers to theextremeiy used forests and wildlands ol the developing countries on which thepopulation exerts increasing .pressure and is depenban-t on by utilizing a largevariety of wood and non-woodforest products. Thbse types 3 to 6 will be iestrictEdto natural parks or to vegetation t-vpes under "wilderneii management" and forestsand wildlands in remote and non-managed lands.

Integrating (_= restoring,-maintaining^or introd!c!ng) fire into forest managementof the densely populated countries.of the old wor:ld and the tropicar/subtlopicalregions may be restricted to fire regime type 1 or, to a lesser exteni Wpe z.Thit typg of regime is characterized by s!ror_t. feturn, fire intervals anri low-intensityfires -and generally maintains^.a serial sub-climax (fire climax) stage of vegetationdevelopment. Su-ch frequent fires are common in a variety of

.foreit and shlubland

communities within the lower latitudes.The ignition of the fires is mainly man-caused and not planned. It follows often inthe wake of extensive forest-land use, particularly grazing practices (seeGOLDAMMER 1988).

P"-PloJ:{loJl_eg.9t^qlion.degradation depends highly on the frequenry of burning.I-€ HOUEROU (1974) has shown that the mediierranean Quercis ttex foreitdegradation varies in respect to the fire regime and the soil and geologicalconditions.on the other hand some forest communities as pine (pirus spp.), eucalypt(Eucatypttu spp.) or teak (Tectona grandb) forests and a vaiiery of dry deciduoisand semi-deciduous forests may show remarkable tolerance t6 freqdent surfacefires.However, most of the fires are started accidentally or intentionally by traditionalland treatment practices. Thls, the existing frequen-tly burnt plant c6minunities aregenerally not the result of a "prescribe-d firb regime" in which all ecologicalinteractions are considered.Consequently almost all unplanned fire climax forest associations are not in astable, dynamic equilibrium, F.y. are rather subjected to Iong-term degradationprocesses which become visible only after generations.

Maintaining a desirable and probable already prevailing-forest type by prescribedfire reouires both a spatial ahd a temporal itiatificatioi of the't'ire 6n'vironment(prescribed fire regimbl in oiaer io avoid site disturbance. This corresponds to thenegative effegjs of uncontrolled silvopastoral (glu?,lg) techniques which may beovercome by "prescribed grazing" management (GOLDAMMER 19gg).

Flowever, the development of a fire management program must not take intoconsideration only the use of prescribed fire Uut htsd the alternatives in fueltreatment and the-possible or prdferable advantages of fire exclusion.

The commonly practiced objectives of prescribed fire, as discussed in thisworkshop, embrace:* fire hazard reduction fuel treatment* habitat management wildlife, Iivestock, pest control* site preparation . planting, narural rdproduction* species- composition competitive/desired vegetation* accessibiliry recreation, aesthetics -* preattack planning buffer zones, fuel breaks

Most of these short-term goals T3y be easily reached by developing appropriateprescribed burning techniques. However, the long-term impacf of fiie mby bedetrimental.

24

A variety of exampies show that other goals of environmental management may bejeopardized.

3. LIMITS OF PRESCRIBED BURNING

3.1. Invasion of undesirable species, change of species composition

Frequent burning leads often to the invasion of endemic plant species which areadapted to the post-burn conditions andlpr to the fire itsdtf. In addition,introduced exotic species may also become very aggressive on repeatedly burntIand. This invasion'process becomes especially'pr65'lematic if thej fire-fo"llowerstend -to-occupy the site completely and replace the ground vegetation.The-following examples ref-er m-ainly to anthropogehetic fire iegimes characterizedby short return interval surface fires :

I

* Pteri"dium aquilinumThe bracken fern is a common-aggr-essive fire follower in many vegetation types ofthe world. A site occupied by bracken fern becomes useless ior fivestock giazingand impedes the natural regeneration of forest stands. Bracken fern becomes aproblem even in tropical. submontane fire climax communities, e.g. in the pinelands of Sumatraflndonesia (Pinus merlatsii) and in neighbouring countries.

* Imperata qtlindicaThis grass is one o.f.thgmost aggressive colonizers of burnt land in the tropics andsubtropics. It usually follows after slash-and-burn agricultural practices and formsdense carpets which are not suitable for grazing and extremely difficult to re-convert inlo forested l_a1d..It spreads into almost "all degrading piant communitiesof the tropics by establishing a short fire ryqle, unsuii-able tof anv fire-sensitiveplant. In Indonesia alone more than 16.100 ha of former rain 'forest land isoccupied by Imperata fields (F.A.O. 1981).

* Eupatoium odoratum and Lantana spp.Eupatoiury _is 1we9{Y colonizer of disturbed sites and is found throughoutcontinental South and South East Asia (e.g. India, Burma, Thailand).A similar pr..o.b-lem is created by the fast spieading Lantana spp. which may becomea serious wildfire problem during droughi periodi.

* Melaleuca quinqueneruiaMelaleuca is not endemic in North America. Its introduction early this century intoSouth Florida ecosystems _caus€s severe problems by replacing the nituralvegetation. \tekpvga is highly fire adapted

-and occupi6s alieady Extensive land

area within South Florida.

* Schimus terebinthifuliaBrazllian pepper

_ ii another naturalized exotic evergreen shrub species which

threatens South Florida's native vegetation

* Serenoa repensSaw palmefto, an endemic species, is also extending its range within Florida.Following after fire the palmetto now dominates many sites formerly occupied bypine, often to the extent that such areas are called "palmetto prairies" (WADE &al. 1980, WOODALL 1983).

25

Fire selection indu-ced . by prescribed fire and the overall tendenry towards a

vegetation type dominated by fire resistant plants is often discussedcontroversially. In Australia the debate is still going oir whether prescribed burningis advantageous or not because conservationists feel that the Endemic flora andfauna needs to b-e p^r^otected by the impact of fire selection (SHEA & al. 198L,JOHNSTON & al. 1982).

3.2. Interactions with secondary pests

The interactions between forest fire, insect attack and host tree are not yet wellunderstood. It is known that a variery of inseits is attracted by freshly burni stands,orienting themselves by infrared or CO2 sensors.

Algry phenomenon has been described in the Philippines. GOLDAMMER (7987,L988 in prep:) found that the exotic lps calligraplzris is highly attracted by fieshlyb.gpt (prescribe4 or a-ccidentally) stands within fhe exended iire climax pine land's(Pinus kesrya) of Northern Luzon.Since its introduction during the second_World War, the beetle has aggressivelyextended its range and represents .now ttre major threat to the forest Eosysterirthis insect problem may jeopardize all efforts towards integrated foresl firemanagement.

The fire-caused physical d,amage of trees may also create considerable problems.In Australia it was found that fire scars are a significant point of entry foi termites(e.g.- Coptotermes .acinaciformis and Mastoterrnes darytiniensis) invading livingeucalypts and causing structural weakening (STOCKER and MOTT 1981).-

3.3. Erosion

There are numerous findings.available on soil denudation and erosion followingpre.scribed or natural fires. This problem becomes especially severe in forest standlwhich have a short return interval fire cycle. Extended ardas of fire climax forestand tree savanna communities such as pine lands and all kind of dry deciduous andsemi-deciduous forests are burnt annually.

.Er-osion is particularly severe on the- sloles of the submontane and montane pinebelts. In _the tropical dry deciduous forest and the tropical pine lands fires usuallyburn at the end of the dry season. The braking rains hii the 6are soil.This erosion process is often not visible because the trees of the old stands aregenerally not affected by the fires. However, within an extremely fiSe-adapted teakplaltation (Tgctgytg gry1dis) thqlor,s qUgpsoil may exceed 200omr/ha thioughouta 30 year period (GOLDAMMER 198tu).

3.4. Air quality

C_o_nsidering the emissions of smoke is not a new aspect in fire management. In theUSA exteniive research efforts have been invested into this subject. iocal/regionalsmoke management plans and prescribed ,burning Iimitations (restrictioni) aremore and more enforced.From a supra-regional point of view it is being recognized that the emissions frombiomass burning are a considerable source of atmospheric gases, in particularCOr, CO, CHz and other non-methane hydrocarbons, COS, NoO and NO;;/J.;;;ri#o#'; forest degradarion in rhe tropics 1"rii'e;fi;:r"t'#rirg i,regarded as one of the major causes of atmospheric/climatic change ( see:International Geosphere - Biosphere Program, NATIONAI ACADEMY PRESS1e86).

26

4. NEEDS OF FIRE PRESCRIPTIONS

In many countries of the world fast growing exotic species are used for plantationestablishment. In the afforestation programs of most tropical countries fastgrowing exotics asPinus andEucatyptus spp. are reforested. They are brought froma natural/anthropogenetic fire environment to a management system whichgenerally excludei fire as a management tool. Particularly pine plantations in thefropics ire characterized by fast growth and,high litter production, thus creatingextieme wildfire hazard. ,

Some first steps in using prescribed fire in exotic pine plantations have beenundertaken in Australia,Brazil, Chile and South Africa. They are mainly related toPinus radiata and Pinus elliottii (FoRESTS CoMMISSION VICTORIA,unpublished reports L979 to 1982, GOLDAMMER 1983, SOARES 1979, JULIO1975, Van LOON and LOVE 1973, de RONDE 1980, 1982,1983).The most crucial problem in pine plantations is the high litter load (surface andaerial fuels) which create extreme difficulties in developing prescribed firetechniques. However, the fuel moisture regime inside the densely stocked standsand especially inside the needle layers gffel a good chance to be used asprescription indicators (see also HARRINGTON 1987). A pronounced moisturegradient allows the partial burning _o! th9 all Iayer and the draped and aerial fuelswithout exposing the mineral soil (GOLDAMMER 1983).

The most challenging task in prescribed fire research is the question of the Iimitsof fire intensity and its relation to expected fire damage. The search has to look forreliable indicators which go beyond needle/crown scorch or cambium damage.Such tree stress indicators should focus on the interactions between host tree andforest insects. The existing methods of determining tree stress by o.e.p. (oleoresinexudation pressure) and water potential are not completely satisfactory(GOLDAMMER 1983).

5. ALTERNATIVES TO PRESCRIBED BURNING

The function of prescribed fire in ecosystem management and the problemscreated by fire are manifold. Fire exclusion, a turn back to the fire control policy,seems unrealistic in a world in which the wildfire scenario turns out to be moreand more anthropogenetic. Mechanized and chemical treatment technologies areoften energy wasting and uneconomic and may also cause environmentalproblems.

One of the more interesting alternatives is prescribed grazing: silvopastoraltechniques which are to be stratified in time and space, as prescribed fire.Prescribed grazing requires a planning process similar to prescribed burning. Thegrazing targets, however, are different and restricted to the palatable fuel.Ferpeiuatin"g forest land suitable for grazing requires often the iombination oftreaiments iuch as prescribed burning aid grA--zing.

LIACOS (1984, 1986) has recently summarized his experiences qnd concepts oflivestock grazing in mediterraneam warn coniferous forests. Completing !h.rsvaluable information by the experience of forest farming systems as developed inChite (PENALOZA ei al. 1983) aqd Ngy__ZenJand (NEWZEALAND FORESTSERVICE and MINISTRY OF AGRICULTURE AND FISHERIES 1982) it isobvious that silvopastoral practices offer an economic alternative to the traditionalfire management practices.

27

6. CONCLUSIONS

At the end of the 20th century firc regimes of many types of forest and other landare increasingly influenced by-man's ictivities. nopirtation growth and the demandfor more forest products and land suitable -for gg{culture, rEsidential purposes andrecreation exeri mcreasmg pressure on land.'Degrading forests bbcome moreflammable and subjected to more rrequent fire occuirence.The change from.natura-l and pre-settlement fire regimes towards contemporaryanthropogenetic fire regimes requlre conseglrent adaptation of fire managementplalning. The expected neqative rrnpact of fire in defrading forest ecosyst?ms aswell as the interactions with the environment on refional -and even global levelhave to be beared in mind when developing prescribeE fire regimes or a'iternatives.

REFERENCES

BARNEY, R.J. L975. Fire managernent : a definition. J. For.73,498-519.BARROWAS, J.S. 1977. The chalrcnges o{ fgrest fire management, a guest

editorial. West.Wilo,andS 4(1), 55-57. F.A.O: 1981. Tropical forestresources assessmer: project. Forest resources of tropical Asia.Rome, a75 p.

FORESTS COMMISSION VICTCRI A 1979-1982. unpublished reporrs on_ prescribedfire in Racjiata pine plantations.GILI. A.M. l9J?, Effects of fire in Austialiats native vegetation.

CSIRO Div. Plant. Ind. Ann. Rep.GOLDAMMER, J.G. 1983. Sicherung des sudbrasilianischen Kiefernanbaues

durchkontrolliertes Brennen.Hochschulsammlung Wirtschaftswissenschaft, Forstwissenschaft Bd.4, Hochschulverlag Freiburg, 183 p.

GOLDAMMER, J.G. 1986. Technrcal ancl vocational forestry and forest industriestraining, Burma. Forest fire management.FO:DP/BUR/81/001. Tech.Note 5. Rome : FAO, 60 p.

GOLDAMMER, J.G. 1986. Feuer und waldenrwickluns in den Trboen undSubtropen. Freiburgrr Waldschutz Abh. 6",43-57. I

GOLDAMMER, J.G. 1987. T.C.P. assistance in forest fire management.The Philippines. Forest fire research.rO .!C![HI16605'iiT), Working Paper 1, Rome : FAO, 38 p.

GOLDAMMER, J.G. 1987. Wildfires.and foresl development in tropical aridsubtropical Asia : Outiook for the year 2000.In : Wildland Fire 2(li)0, 164-776.Symposium held in zioril 27-30, South I-ake Tahoe, California.USDA For. Ser. Ger;. Tech. Rep. PSW-101, 258 p.

HARRINGTON, M.G. 1987. Preorctingreduition of natural fuels by prescribedburning under Poncierosa Pine in Southeastern Arizoria.USDA For. Ser. Re:;.i'jote RM-472.4 o.

HEINSELMAN, M.L. L978. Fire ii, wilderneps ecosfstems.In : Wilderness man:; i'eme nt, 248-27 8' (J.C. HENDEE & al. eds).USDA For. Serv. M;,,c. Publ. 1365, Washington, D.C.

HEINSELMAN, M.L.1981. Fire ir:rensiry and frequency as factors in thedistribution and stru:iure of northern ecosystems.In: Fire regimes ana ecosystem properties,T-57.USDA For. Ser. Ger;. 'Iech. Rep. WO-26, 59 p.

28

KILGORE, B.M. 1981. Fire in ecosystem distribution and structure :Western forests and s"crublands.In :_Fire regimes and ecosystem properties,58- 59.USDA For. Ser. Gen. Tech. Rep. WO-26, 594 p.

KEELEY, J .8. _197 7. Fire - d epe nd ant, reproduttive strate g ies' in A rc t o s t ap hy lo s andCeanothus. In' : Envirohmental conseqlences of fire hnd fuelmanagement in Mediterranean Ecosystems, 391-396.USDA For. Ser. Gen. Tech. Rep: WO-3, 498 p.

LIACOS, L. 1984. Project goat grazing on mediterranean biushlands and coniferunderstorry vegetation. Unpublished Report Chrysopigi ResearchStation. Thessaloniki Univeisity. 96 p

LIACOS, L. 1986. Ecological and managemerit aspects of Iivestock grazing andprescribed burning in mediterianean warn cSnifer- forests.E.C.E./F.A.O./I.L.O. Seminar on Methods and Equipment for thePrevention of Forest Fires, Valencia, Spain (in presd). '

van LooN, AJ.; LovE, L.A. L973. A_prescribed bu'rning exferinient in youngslash pine. For. Comm. New South Wales Rts. Note 25,53p.

METHVEN,I.R. 1978. Fire research at the Petawawa Forest Experimen't St"tion tthe integration qf fire behaviour and forest ecology for managementpurpory^s._!n_: liry eqqt-ory_in_ Besource Manag-emenr WorkshopProc., 23-27.Inf. Rep. NOR-X-210, North. For. Res. Cent., Can. Foi.Serv., Edmonton, Alberta.

NATIONALACADEMY PRESS 1986. Global Change in the BiosphereGeoslhe:e._I4itill priorities for an IGBP. Washingtoi O.C., 9t p.

NEW ZEAI-AND FOR. SERV., MINISTRY OF AGRICULTT]RE.Forest_farmrng resea_rch at Tikitere. Handbook, L8 p.

PENALOZA, W.R. 1983. Desarrollo ge la investigacion aplicada^al uso multiplodel recurso suelo, mediante sistemas silvo-pastorales en el sur deChile. Universidad Austral de Chile,Faculdad de Ciencias Forestales, 23 p.

de RONDE, C. 1980. Controlled burning under piies, a preliminary classificarionsystem for plantations in the Cape.Suid-Afrikaanse Bosboutydskrif No.l 13, 84-86.

de RONDE, C_. 1982. The resistance of P^inrs species to fire damage.South Afr. For. J. No.122, 22-27.-

de RONDE, C: 1983. Controlled burning i_n pine stands in the Cape :the influence of crown scoich on tree srowth and liiter fall.Suid-Afrikaanse Bosbourydskrif Dec. ig8:, 39-+t.

SANDO, R.W. 1978. Nat_u_ral fireregimes and fire management, foundations fordirection. West. Wildlands 4(4),34-42.

SHEA S.R.; PEET, G.B.; CHENEY, N.P. 1981. The role of fire in forestmanagemel!. In : Fire and the australian biota (A.M. GILL & al.

_gdl), 443-470. Austr. Acad. Sci., Canberra,582 p.soARES, R.v. 1979. Queima controlada em plantag6es de Pinus spp. na regiao

de Sacramento (MG). Rev. Floiesra 10(2) 33-40.WADE, D.; EWEI, J.; HOFSTETTER, R. 1980. Fire in Sourh Floridas

Ecosystems. UF-P4 For. Serv. Gen. Tech. Rep. SE-17, L25 p.WOODALI, S.L. 1983. Establishment of Melaleuca quinquenervia seedlings in

the pine-cypress ecotone of Southwest Florida.Florida Scientist 46,65-72. ,

29

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NATURAL FOREST COMMUNITIES

NO FIRELowland troplcal rain f st?

NATURAL FIRE CLIUAX FORESTI

INFREQUENT, SHORT RETI'RN INTER-vAL, LOW-IN?ENSITY SURFACE TIBES,HIGH-INTENSITY CROUN FIRES

sclerophyll forests

ANTTIROPOGENETIC FIRE CLIUAXgrLrlY)

FREQUENT, SHOnT RETURN INTERVAL,LOI{-INTENSITY SURFACE FIBESPine forests, dry deciduous forests.No or low eroslon.

PREQUENT, SHOST BETUBN INTEBVAL,LOT-INTINSITT SURFACE FISESPlne forests, dry dectduous torsstg.Heavy eroslon

NATURAL,/ANT'IIROPOGENET I C SA VANNAS

FREQUENT (1- to 10 year RETURNINTERVAL), LOy- and EIGH-INTENSITISURTACE FIRES.lYee, shrub and grass savannas.

DEGRADED SAVANNAS

LONG RETIIRN INTEBVAL, LOW-INTENSITYSUBTACE FIBES

Sparse fuel, wide-spaced vegetation.Deserti fi cati on.

EratsElub,OridE.-{EA

II

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Figure 2

Types of tropical,/subtropical fire regimes under ageneralized framework of ecological a;d anthropogeneticinfluences (modified after GOLDAMMER 19g6). r-

NATURAL FOREST COI&IUNITIES

LONG RETURN INTEBVAL, STANDREPLACEITENT FIRESl{ontane, subalplne coniferousforests; tropi.cal rainj forest,

t-swamp forests.