Dominican Republic Fire Assessment

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Fire Management Assessment of the

Highland Ecosystemsof the Dominican Republic

THE GLOBAL FIRE I NITIATIVE

GFI publication no. 2004-2

October 2004


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Citation: Myers, R., J. OBrien, D. Mehlman, and C. Bergh, Fire ManagementAssessment of the Highland Ecosystems of the Dominican Republic. GFI publicationno. 2004-2. The Nature Conservancy, Arlington, VA.

TNCs Global Fire Initiative acknowledges the financial support of the USDA ForestService International Programs for the development of this assessment.

For more information, contact:

Ronald MyersTNC Global Fire InitiativeTall Timbers Research Station13093 Henry Beadel DriveTallahassee, FL [email protected]://nature.org/fire

Cover Photo: View of Hispaniolan pine forest in Juan B. Prez Rancier National Park,Dominican Republic. Ronald Myers

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Section Page

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Focus & Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Fire & Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Pinus occidentalisForest, Woodland & Savanna Ecosystems . . . . . . . . . . .4Cloud Forest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Mixed Pine-Broadleaved Forest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Observations & Interpretations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Fire Ecology & Fire Regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Role and Impact of Forest Exploitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Conclusions & Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Key Ecological Attributes Related to Fire . . . . . . . . . . . . . . . . . . . . . . . . . . .17Recommend Fire Management Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Suggested Next Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

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(6) Identify projects and programs that couldbe developed and implemented by The NatureConservancy, its NGO and bilateral partners,and the Dominican government to reduce thethreat of altered fire regimes in the Central

Highlands.

(7) Identify land management staff who couldparticipate in training courses, exchanges, andmentoring programs.

(8) Provide fire managers and conservationspecialists in the Dominican Republic withrecommendations on strategy and actions toreduce the threat of altered fire regimes.

(9) Propose and discuss the possibility of hold-ing a Fire Learning Network workshop in theDominican Republic on fire in highland pineand savanna ecosystems in the Latin America.

This assessment was conducted as part of theLatin American & Caribbean Fire LearningNetwork (LACFLN) funded through TheNature Conservancy by the USDA Forest

Service International Programs.

Focus & Constraints

Information in this report is based on observa-tions by, and discussion between, theAssessment Team and its Dominican hostsduring four days in the field and two days ofmeetings with TNC staff and their NGO andgovernment partners. The Teams observationsin Madre de las Aguas (Cordillera Central)were limited to sites (1) along the main road

through Juan B. Prez Rancier National Park(also known as Valle Nuevo) from ElConvento to San Jos de Ocoa, (2) in theCaada de La Zanja near the Dr. RafaelMoscoso Puello Research Station, and(3) along the road to the top of Alto Bandera.

In Bahoruco National Park, the Team observedsites (1) along the road from Puerto Escondido

to El Aguacate, then (2) south along theInternational Highway (on the Haitian bor-der), followed by (3) stops along the AlcoaRoad ending at the visitor center at Hoyo dePelempito.

This itinerary provided broad transectsthrough:(1) the Hispaniolan pine forests and savannasin the Cordillera Central,(2) cloud forests at the Ebano Verde ScientificReserve and at a site in Valle Nuevo calledJurassic Park, and(3) pine forests and hardwood forests on lime-stone substrates in the Sierra de Bahoruco.

These areas by no means afforded the Teamthe opportunity to observe the full range offorest conditions nor the effects of all therecent fires in the Hispaniolan pine forests andrelated ecosystems. The Team was also limitedin its observations of the forest/agriculturalinterface where many fires that affect theforests originate, although they were able toget good views of the differences and effects

along the border with Haiti and Sierra deBahoruco National Park. We were also unableto observe and evaluate some key vegetationtypes such as the Manaclaresa wet tropicalforest with abundant palm, Prestoea montana.

Furthermore, the interpretations presented inthis report are largely inferences based on theTeams keen observations, professional expert-ise and experience, and drawn from scientificstudies in similar ecosystems elsewhere in theworld. The validity of these interpretations willhave to await more detailed scientific studiesand management experience.

There is a research team from the Universityof Tennessee currently working on post-firevegetation dynamics, dendrochronology, vege-tation history, and fire history in theHispaniolan pine forests of the Cordillera

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Central. There is another research team fromCornell University looking at vegetation-environmental relationships,including fire, in the distribution and structureof montane types in the Cordillera Central.

The Cornell project is funded by The NatureConservancy through the Mellon Foundation.The references from these projects, Horn et

al. (2000), Horn et al. (2001), and Shermanet al. (2003), provided the Team with researchresults and background information in theCordillera Central. Background on the floris-tics of the pinelands of the Sierra de Bahoruco

is found in Fisher-Meerow & Judd (1989).Latta et al. (2000) discuss fire issues in theSierra de Bahoruco.

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There are three main vegetation types withinthe Juan B. Prez Rancier National Park andin Sierra de Bahoruco National Park that areaffected by fire: (1) Hispaniolan pine forests,woodlands and savannas, (2) mixed pine-broadleaved forests, and (3) cloud forests. Thepine forests are dependent on fire; the mixedpine-broadleaved forest is an artifact of achanging fire regime; the cloud forest is fire-sensitive (Figure 1).

Pinus occidentalisForest,Woodland & Savanna Ecosystems

Pinus occidentalis, known as Hispaniolan pineor West Indian pine, is considered endemic tothe island of Hispaniola. It once covered anestimated 3 million ha, but has been depleted

to perhaps less than five percent of that area(Darrow & Zanoni, 1990). Virtually all of theremaining forests are in the DominicanRepublic. The species occurs at elevations of2003000 m in the Cordillera Central and inthe Sierra de Bahoruco. The more extensiveand pure stands occur at 9002700 m. Thesoils in the Cordillera Central are nutrient-poor, shallow acidic clays mixed with igneousrock; in the Sierra de Bahoruco the soils arederived from limestone. Rainfall ranges from

12002300 mm, with a three- to five-monthdry season during the winter when there areoccasional frosts above 1600 m.

Because of the lack of marked seasonality inthe tropics, high-altitude environments have

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etation 2fire & vegetation

Figure 1. Locations of Juan B. Prez Rancier and Sierra de Bahoruco national parks and pine forests.

Dark green = Montane Pine Forest & Mixed Pine-Broadleaved Forest. Aqua green = Pine Woodland.

Purple = Montane Rainforest & Cloud Forest.

Juan B. Prez Rancier National Park

Sierra de Bahoruco National Park


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relatively cold nighttime temperatures year-round. This contrasts with highland environ-ments at higher latitudes where there ismarked seasonality. The cold environment lim-its growth rates in these pineland ecosystems

compared to pinelands at the same latitude butat lower elevation. Thus, growth rates, fuelaccumulation and decomposition are relativelyslow compared to lowland tropical environ-ments.

Where the pines still occur in Haiti, the inva-sive alien shrub Syzgium jambosforms densethickets beneath the pines, which purportedlyexclude fire (Darrow & Zanoni, 1990). The

most serious invasive species problem weobserved was the spread of non-nativeCaribbean pine (Pinus caribea) from inappro-priate reforestation efforts near Valle Nuevo inthe Cordillera Central and along the AlcoaRoad in Sierra de Bahoruco National Park.

The affinity ofPinus occidentalisto severalendemic pine species in Cuba is not clear.Several authors report it on both islands, theCuban variety beingPinus occidentalisvar.cubensis. There is apparently considerable vari-

ation among pine populations in eastern Cubaand the possibility of hybrids ofPinus cubensisand Pinus occidentalishas been noted. Borhidi(1996) states that these morphologicallydiverse populations in Cuba are united underthe name Pinus maestrensis. Farjon & Styles(1997) maintain that reports ofP. occidentalisfrom eastern Cuba are probably erroneous andlikely pertain to Pinus cubensis. P. occidentalishas three to four predominantly five-needled

fascicles, while both P. cubensisand P.maestrensishave fascicles of two to three nee-dles (Bisse, 1981). The pine in the Sierra deBahoruco has been described as P. occidentalisvar. baorucoensis, although this variety is notgenerally recognized (Farjon & Styles, 1997).

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Figure 2. Danthonia domingensistussocks in a savanna in Valle Nuevo that was burned in 2001. Note

limited amount of fuel accumulation and lack of fuel continuity between tussocks two years post-burn.

This illustrates that in this cold highland environment fuel accumulation is relatively slow. (Photo: R.

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Its morphological characteristic may be anexpression of it growing on calcareous soils.

The IUCN Species Survival Commission(1994) lists Pinus occidentalisas vulnerable

and in need of conservation and managementmeasures.

Due to the marked substrate/soil differences,the floral species composition is quite distinctbetween the forests and savannas in theCordillera Central and those of Sierra deBahoruco. This differentiation may have alsobeen influenced by the fact that Sierra deBahoruco once formed a separate island and

was isolated from the Cordillera Central. Theacid soils of the Cordillera Central supportshrub species such as Lyonia heptamera,Myrica picardae, Myrsine coriacea, Ilex

tuerkheimii, Garrya fadyenii, and Baccharismyrsinites. The tussock-forming grass

Danthonia domingensisdominates grasslandsand savannas, and is even common in relativelydense forests (Figure 2).

In contrast to the Cordillera Central, the

understory and ground cover vegetation in thepine forests of Sierra de Bahoruco are reminis-cent of species found on calcareous rocklands,e.g., the palm Coccothrinax scoparia, the agaveAgave antillana, and shrubs such as Cestrumbrevifolium, Chamaescrista glandulosa, Lyonia

truncata, Myrica picardae, Senecio picardae,

Hypericum hypericoides, and Coreopsisbuchii. Grasses are abundant, but Danthoniadomingensisis not one of them (Figure 3).

Cloud Forest

Mountains at tropical/subtropical latitudes fre-quently reach the height of, or pierce, the tradewind inversion which, at the latitude of theDominican Republic, is strongest and lowest

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Figure 3. Pineland ground cover on limestone substrate in Sierra de Bahoruco National Park. Pine

needle litter forms a continuous fuel and is the primary carrier of fire. (Photo: R. Myers)


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Fire Ecology & Fire Regimes

The historical distribution of Hispaniolan pineis largely an artifact of fire, i.e. these forests arefire-maintained. Holdridge (1949) was proba-bly the first to note the ecological role of fire inmaintaining the pine forests on Hispaniola.The long history of fire in these pine andsavanna ecosystems has been documented byHorn et al. (2000) and Clark et al. (1997).These studies dated charcoal from soil andsediments from the late Pleistocene (42,000

yrs BP) and throughout the Holocene (last10,000 years). The incidence of fire pre-datesthe arrival of humans (60007000 yrs BP).Pollen analyses suggest, but do not confirm,that human activities may have resulted in theexpansion of pine down-slope. The overallfindings, however, indicate that the fire regimehas not changed significantly over the past5000 years, and that recent human activitieshave not necessarily favored pines and savanna

vegetation over broadleaved forests in theCordillera Central, as is sometimes suggested.Frequent fires do limit the areal extent anddistribution of broadleaved cloud forest vege-tation, and the boundary between this foresttype and pine or savanna may wax and wane inany given area depending on the incidence offire.

Today, many fires are probably of human ori-

gin, but because few records have been kept,the incidence of lightning-ignited fires and therelative role of human versus lightning fires isnot known. The human sources of ignition areescaped fires from around homes and fromagricultural burning, fires set by hunters, acci-dental ignitions by local residents and visitorsto the regions national parks, and revenge orprotest burning against individuals or the

government. Guerrero & McPherson (199_)

describe the recent history of fire in Juan B.Prez Rancier National Park (Valle Nuevo).McPherson et al. (199_) interviewed localcommunities regarding their use and attitudestoward fire and found that escaped agriculturalfires, though important, have probably beenless of a factor affecting the pine ecosystemsthan fires set as a form of protest or revengerelated to socio-political issues. The IntegratedEcological Evaluation of Juan B. Prez Rancier

National Park,which contains these two citedpapers, presents a map of large fires document-ed between 1983 and 1998. There were sevenregistered fires; the largest, in 1983, covered51,200 ha.

Fire has been an important influence affectingthe current distribution and structure of thepine forest and savanna ecosystems. Many pineforests, woodlands, savannas, and open grass-

lands throughout the world depend on specificfire regimes for their persistence and charac-teristics. Without fire they will change tosomething else, with the loss of not only thepines but also many of the plant and animalspecies that are specific to those habitats. TheHispaniolan pine ecosystems are no exception.The fire regime that maintains viableHispaniolan pine ecosystems is probably bestdescribed as mixed, i.e. a combination of fre-

quent, low-intensity fires restricted to the fuelson the forest floor (e.g., grasses, pine needlecast, small shrubs), and high-intensity stand-replacing/crown fires that kill many of thepines in their path. The high-intensity compo-nent is mediated by the interaction of winds,humidity, slope, fuel accumulation, and standdensity. These types of fires are more likely tooccur during very dry conditions, on steep

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slopes, with up-slope winds, and over expansesthat have accumulated fuels during extendedfire-free periods.

The size of the area affected by these high-

intensity fires may be limited to small stands ormay involve multiple slopes and ridges acrossthe landscape. Conversely, low-intensity sur-face fires would be common under moderateburning conditions and/or low fuel loads, onrelatively flat ground, in areas burning withfires backing down or flanking across slopes,and with fires backing into the wind. Undermoderate to mild burning conditions, fires inopen stands and in long-unburned savannas

may be of higher intensity than in adjacentdense pine stands because of differences in the

surface fuel structure (i.e. upright grasses ver-sus compact, horizontal, pine needle litter),and because pine stand density affects windspeed, fuel moisture, and fuel temperature(through shading) as long as conditions are not

conducive to crowning (Figure 7).

The Hispaniolan pine has specific adaptationsthat allow it to survive and/or respond favor-ably to fire. As seedlings, the pine does nothave any adaptations to survive fire. This indi-cates that the mean fire return interval wouldhave to be long enough to allow some of thetrees in a stand to become large enough to sur-vive fire. There is a relationship between sur-

vival size and fire intensity. Some smaller treeswill survive low-intensity fires while none may

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Figure 7. Fire effects resulting from a heading fire burning from an open savanna into a closed pine for-

est. Note greater mortality of small trees and the height of dead branches at the forest edge. As the

fire entered the forest, its behavior moderated considerably, greatly reducing the effects on the pines.

The burn occurred in 2001. This is probably a normal dynamic at the savanna-forest edge where the

pines encroach on the savanna during fire-free intervals, and then are killed back when a fire occurs.

(Photo: R. Myers)


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survive a high-intensity fire. Larger individualshave two adaptations that increase their proba-bility of surviving fire: (1) thick bark that pro-tects the cambium from heat, and (2) a naturalpruning of lower branches that keeps growingbuds high above the lethal heat of a surface fire(fire may also be a pruning agent). Horn et al.(2001) found that pine mortality in fires is

strongly correlated to stem diameter. Treeswith diameters over 10 cm survive fires morefrequently than smaller-diameter trees.

Irrespective of pine survival or mortality, fireprepares a mineral soil seed bed, makes nutri-ents available to facilitate growth, and reducesshade and other competition from otherspecies, facilitating regeneration and growth of

pine. Fire also may thin dense stands of pine,leading to more vigorous growth, and morefire-tolerant, open stands.

What is not known is the minimum fire returninterval that will allow the persistence of pineon a particular site. Survival will be partly afunction of site productivity, i.e. how fast the

young trees grow, and fuel conditions: type offuel, amount of fuel and fuel moisture, all ofwhich contribute to fire intensity. Figure 8shows size of pine regeneration after a fire in1992 in savanna grass fuels in the CordilleraCentral. A fire burning with the wind (head-ing fire) under these fuel conditions will likelykill the regeneration shown in this picture. Alower intensity fire, backing into or moving

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Figure 8. Eleven-year-old pine regeneration in savanna fuels after a fire in 1992, Valle Nuevo. It appears

that a heading fire killed scattered large trees that were in the savanna and damaged trees at the edge

of the forest. The fire then moved through the forest as a lower-intensity surface fire and had no

impact on the trees in the dense stand. Given the current fuel conditions, a heading fire in the regener-

ation would likely kill most individuals, but it would still have little impact on the mature forest because

of the low amount of fuel and shaded conditions. Under severe burning conditions, the dense forest

would be prone to crowning fire resulting in the loss of most of the trees. (Photo: R. Myers)


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perpendicular to the wind (flanking fire), mayallow considerable survival of trees this size.This suggests that the minimum fire returninterval for pine survival in grass fuels is 10 to 12years. This minimum may be considerably differ-ent in woodland fuels or the pine litter/sparsegrass fuels found in Sierra de Bahoruco, or else-where in the Cordillera Central.

Fires in more mature stands can be consider-ably more frequent than 10 to 12 years. Thereturn interval would be limited by fuel accu-mulation, and could be as frequent as two tofive years. Frequent fires would afford standsof larger trees protection from wildfires underextreme conditions because fuels would rarelyaccumulate to support destructive fires(Figures 9 & 10).

The shrub layer also responds to fire. Horn etal. (2001) documented high (95100%) basalresprouts of most understory shrubs two yearspost-fire in an area burned in Alto de laPrimera Caada in Juan B. Prez RancierNational Park. This, coupled with survival oflarger trees and recruitment of pine seedlingsand the persistence of tussock grasses point toan ecosystem that is adapted to fire, anddependent on periodic fire.

Role & Impact of Forest Exploitation

The current structure and dynamics of theHispaniolan pine forests and their relationshipto adjacent cloud forest and broadleaved foresthas been strongly influenced by previous log-ging events. Commercial logging of the pinesin the Cordillera Central began in the early

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Figure 9. Pine stand in Sierra de Bahoruco National Park that burned within the past year. The fire had

no impact on the overstory pines. It may have killed pine regeneration, but the stand was already fully

stocked. Most of the agave survived the fire, suggesting a very low-intensity burn. Understory shrubs

are resprouting. A thin layer of pine needles covers the ground surface, which could potentially burn

again. (Photo: R. Myers)


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1900s. The intensity of extraction increasedafter World War II, and reached its peak inthe final decade of the Trujillo regime whenthe road through Valle Nuevo was completedin 1952. Between 1943 and 1959 there were 19sawmills inside what is now Juan B. PrezRancier National Park. Although we have nospecific information, we assume that the pine

forests of Sierra de Bahoruco where exploitedat about the same time and at the same intensity.

Besides changing the structure of the pineforests, deforestation associated with loggingled to the migration of people who convertedonce forested areas to agriculture. See refer-ences in Guerrero & McPherson (199_) for

more information on forest exploitation andland use in the Cordillera Central.

The pine forests observed during this fireassessment exhibited a structure strongly influ-enced by past logging and subsequent fireevents. All of the forests observed in both theCordillera Central and in Sierra de Bahoruco

were second growth. In places, there were iso-lated large pines with flat-topped crowns char-acteristic of old-growth trees that probablyescaped logging. Several different forest struc-tures were evident that are probably the resultof specific fire histories after the areas werelogged. They are:

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interpretationsFigure 10. Frequently burned pine forest on left contrasts with a long-unburned pine forest on the right.

Pines cannot regenerate under the long-unburned conditions and many ground cover species are

being shaded out. In the continued absence of fire, pines will disappear from the site. In the meantime

pine needle litter and shrub fuels are accumulating making the site susceptible to a stand-destroying

fire. Prescribed burning could maintain the condition on the left and restore the forest on the right to a

more healthy state. (Photo: R. Myers)


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(1) Dense even-aged stands of pole-sized treeswith occasional emergent seed trees (Figure11). These stands likely developed after thearea was logged. The emergent old growthtrees had fire scars and may have been left for

that reason. These areas have either notburned for many years (possibly since the1950s), or they have burned with very low-intensity understory fires burning through thelitter/grass fuels that had little impact on thepines. In places, there was a deep (>10 cm)layer of duff. Under extreme burning condi-tions, these stands would be susceptible tostand-replacing fires. In areas with consider-able duff accumulation, even low-intensity sur-

face fires under extremely dry conditions couldbe lethal to the pines by killing feeder roots inthe duff and by the heat from smoldering com-bustion killing the cambium at the base of thetree. These conditions notwithstanding, fuels

could be easily reduced in these stands withappropriately applied prescribed burns.

(2) A mosaic of: dense saplings and no largetrees, open stands of large trees with grasses

and no reproduction, and scattered large treeswith dense reproduction underneath (Figure12). These patches reflect where: (a) overstorytrees may have been killed by fire and havereseeded from adjacent seed trees; (b) oversto-ry trees were removed during logging andregeneration is periodically killed back beforethe trees reach a likely survival size; (c) fre-quent surface fires have prevented or killedregeneration but spared the large fire-resistant

trees; and (d) fire may have killed a generationof reproduction, but has been fire-free longenough to support vigorous reproductionunder large fire-resistant trees. In the contin-ued absence of fire, each of these would devel-op the dense structure shown in Figure 11.

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Figure 11. Densely stocked stand of second-growth pine in Valle Nuevo that may have become estab-

lished after logging or a severe, stand-replacing fire. These types of stands are susceptible to stand-

replacing fires. Fuels and stand density could be reduced with appropriately applied prescribed fire.

Under moist conditions these well-shaded forests would likely stop fires burning in adjacent savanna.

(Photo: R. Myers)


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(3) Even-aged or uneven-aged stands of pineswith clumps of reproduction in small openings(Figure 13). This structure likely develops whensurface fires leave most large trees unaffected,but light gaps in the canopy are created whenseveral large trees are killed by a fire, lightning,windthrow, or other factors such as disease.The burning of surface fuels and vegetationcoupled with the increased light intensity cre-ate conditions conducive to the establishmentof a clump of reproduction in the gaps. This

reproduction may be (a) killed by the next fire,recreating the gap, (b) thinned by repeatedfires, or (c) thinned through competition.

(4) Stands where non-native Caribbean pine(Pinus caribea), planted as part of reforesta-tion projects, dominates former Hispaniolanpine sites (Figure 14). This structure dominat-ed the landscape along the Alcoa Road and

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Figure 12. A mosaic of stand structures created by past fire events illustrating regeneration in patches

in where large trees were killed by a fire, and regeneration under large trees that survived the fire. At

this stage another fire could (1) kill all the regeneration but spare the large trees, or (2) kill only the

smallest of the regeneration leading to an open stand of pines of mixed ages. (Photo: R. Myers)

Figure 13. Stand of mature pine with considerable

pine regeneration in Sierra de Bahoruco. Light

gaps in the canopy will favor the growth of pines

in patches. Seedlings under pine trees are likely to

be killed in the next fire, while larger saplings in

gaps are more likely to survive because of their

larger size. Fire is an important thinning agent

where there is dense reproduction under pines.

(Photo: R. Myers)


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around the Hoya del Pelempito visitor centerin Sierra de Bahoruco National Park. Althoughthe displays at the visitor center highlight theendemic Hispaniolan pine of the DominicanRepublic, most of the trees in the area are

Caribbean pine, and perhaps other introducedspecies. The elevation and soils of this area arevery suitable for Caribbean pine, and it

appears to be a very aggressive invader favoredby the frequent fires. In contrast, Caribbeanpine has also been introduced at higher eleva-tions in the Cordillera Central, and it is clearlynot adapted to these conditions. The small

stunted trees could easily be eliminated in afire.

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Figure 14. Aggressive Caribbean pine regeneration along the Alcoa Road in Sierra de Bahoruco

National Park. This is an unfortunate non-native introduction to an island ecosystem that has an

endemic pine species that would normally occupy this site. Consideration should be given to removing

these trees and replanting or reseeding with Pinus occidentalis. (Photo: R. Myers)


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Key Ecological Attributes Related to

Fire(1) The Dominican Republic has some of thebest examples of intact subtropical montaneecosystems in the Americas, consisting of anendemic pine forest ecosystem (Pinus occi-dentalis), montane grasslands, elfin (dwarf )cloud forest, and lower montane broadleavedforests.

(2) The landscape encompassing these ecosys-

tems represents a classic example of thedynamic relationship between fire-main-tained/fire-dependent pine forests, woodlands,and savannas and fire-sensitive cloud forestsand lower-elevation tropical broadleavedforests.

(3) The long-term history and role of fire inthis landscape is not in doubt. Studies byresearchers at the University of Tennessee have

documented a long history of fire in the pineand savanna ecosystems.

(4) The importance of fire in maintaining thepine and savanna ecosystems can be inferredfrom (a) this history coupled with the life his-tory characteristics and adaptations of the pineand other key species, (b) the structure ofexisting forests, and (c) the effects of recentfires.

(5) Fires originating in the pine and savannaecosystems are important in determining thedistribution and extent of cloud forest andtropical broadleaved forest vegetation, i.e. fireplays a role in these ecosystems and may beimportant in creating certain habitats anddetermining the relative abundance of species.

(6) A general synopsis of these natural land-scape dynamics and species characteristics are:

a. Fire generally originates in the highly-ignitable and flammable pine and grasslandfuels; i.e. the primary fuels of most fires aregrasses and pine needle litter.

b. The pines, dominant grasses, forbs, andmany of the shrubs have developed adaptationsto respond positively to fire, e.g., large pines

with thick protective bark and high openbranches readily survive low-intensity surfacefires. Pine seedlings and many (but not all)saplings may be killed in these fires, but thefires remove grasses and shrubs that competewith pines and release nutrients from the ashcreating a favorable seedbed for pine regenera-tion. The Hispaniolan pine appears to be aprolific producer of seed, so burned areas arereadily reforested from surviving trees or from

trees in nearby unburned areas.

c. The dominant grasses are clump-forming,i.e. they are bunch or tussock grasses typical offire-maintained ecosystems. They produce afuel arrangement that is easily ignited andreadily carries fire even when green and/orunder relatively moist conditions. The fuel isfine, very loose, and well aerated; the deadblades are held for a long time within the

clump; and the blades possibly have chemicalcompounds that make them highly flammable.

d. The grasses, many of the forbs, and theshrub species have the ability to resprout afterfire, i.e. the ground cover recovers rapidly afterfire. Although erosion after fires is widespread,particularly on steep slopes, the root stocks of

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shrubs and grasses are not killed so they con-tinue to hold soil and limit its loss from slopes.

e. Fire in the pine forest and savanna is not anecological succession-initiating process. What

burns simply recovers.

f. Fires originating in the savanna and pine for-est frequently go out when they reach thecloud forest or tropical broadleaved forest. Thelatter two forest types produce less flammablefuels, which are more compact and less aerated,retain moisture, and are shaded. In the case ofthe cloud forest, it is located in a moisture belt,i.e. a generally wetter environment than found

in most of the pinelands. Other tropicalbroadleaved forests are frequently located inmoist ravines and drainages. These differencesin environment, fuels, and fire behavior inter-act to produce the abrupt boundary that isoften seen between fire-maintained and fire-sensitive ecosystems.

g. Fire is an important disturbance process incloud forests and tropical broadleaved forests,

but because it does not re-occur as a pre-dictable event, many species in these two vege-tation types do not have adaptations torespond to it. That notwithstanding, occasionalsmall fires may be important in creating uniquehabitats for certain species, and for determin-ing the dominance of certain species.

h. During the dry season, and particularly dur-ing protracted droughts, fires originating in thepine forest and savanna can broach the ecosys-tem boundary with cloud and tropicalbroadleaved forests. Such fires may be verydamaging, and may, if repeated frequently,cause a shift in the boundary.

i. Fire damage in cloud forest and otherbroadleaved forests opens the canopy and cre-ates huge quantities of fuel from dead trees.The open canopy allows more rapid drying of

these fuels, making them more susceptible torepeated burning and loss of the forest.

j. After an initial fire in cloud forest, flammablevegetation, e.g., ferns, can invade and potential-

ly initiate more frequent fires.

k. During extended fire-free periods, the cloudforest and broadleaved forests will encroachupon the savanna and pine forests. The mixed-pine/broadleaved forests described in theCordillera Central and Sierra de Bahoruco maybe the result of these shifts.

l. Fire interacts with hurricanes. Hurricane

damage may produce huge fuel loads that mayallow fire to affect large areas in all of thehighland ecosystems, both fire-prone and fire-sensitive.

m. Key to the integrity of all of these ecosys-tems is fire frequency. Fires need to be fre-quent enough to maintain varied examples ofpine forest and savanna, but not so frequentthat they limit pine regeneration over large

areas. Conversely, they need to be infrequentand small in scale in the cloud forest andbroadleaved forest. Keep fire out of the savan-nas and they will first become pine forests.Keep fire out of the pines and (1) fuels willaccumulate, (2) which may lead to destructivefires that (3) kill large pines and degradewatersheds. Long-term absence of fire will pre-vent regeneration of the pine and lead to thegradual change to either cloud forest vegeta-tion or broadleaved hardwood forest depend-ing on the environment. If fires are too fre-quent in the cloud or broadleaved forest, theywill change to pineland, savanna or shrubland,and be susceptible to the invasion of non-nativespecies from agricultural lands and pastures. Iffires are too frequent in the pine forest, the for-est will change to savanna or grassland.

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(7) It does not matter if fires are natural orhuman-caused. One is not better or worse thanthe other. The ignition source is not important,rather it is the characteristics of the fireregime. If the fire regime changes or is altered

from what is needed to maintain a particularecosystem, it will change to something else.

(8) It is unknown at this time to what degreehuman-ignited fires escaping from agriculturalclearings that surround, or are imbedded in,the natural areas, or those that are purposelyset, are posing a significant threat to any or allof the ecosystem types within the CordilleraCentral and Sierra de Bahoruco. The incidence

of fires and their effects need to be monitoredin greater detail and to a greater extent.

(9) It appears that frequent fire may be killingback pine regeneration in many areas of theCordillera Central, preventing the develop-ment of more mature forests. Likewise, fire inportions of the Sierra de Bahoruco may bemaintaining shrubland without pine.

(10) Fire has been excluded from some pinestands, either by happenstance or through sup-pression efforts. These stands should havebeen thinned by fire. Current fuel loads andstand density make them susceptible to largecrown fires that will kill trees and adverselyimpact watersheds.

(11) It is likely that escaped agricultural firesand accidental or provoked fires are convertingbroadleaved forests to non-native flammablegrasslands or shrublands, and in the pineforests are preventing the regeneration of pine.This process creates a positive feedback loopwhere fires enter the forest and create moreflammable conditions, which leads to more fre-quent fires and enhanced expansion of non-native grasses at the expense of forests.

(12) Although much needs to be learned aboutthe details of the fire regimes that maintainpine forests and savannas and influence cloudforests and broadleaved forests, it appears thatthe fire regime in the pine/savanna ecosystems

can be described as mixed, e.g., a combina-tion of low-intensity, non-lethal surface firesand high-intensity lethal fires (lethal to thepines). This mix is mediated by time since lastfire (fuel accumulation); burn conditions (e.g.,dryness, humidity, temperature), stand density,slope, and wind speed. Under natural condi-tions, such a fire regime would create a diversearray of habitats, stand densities, and stand ages.

(13) Past logging (everywhere) and fire sup-pression in accessible areas has altered the nat-ural stand structure of the pine forests andmade them more susceptible to fire damage.The reported high level of stand replacing firesin Sierra de Bahoruco (Latta et al., 2000) islikely an artifact of the interaction of relativelyyoung dense stands that developed after log-ging and frequent human-caused ignitions.Dense, young stands, not subjected to low-

intensity understory burns, are more suscepti-ble to crown fires and pine mortality, thanforests in a landscape of larger, more widelyspaced trees, mixed with smaller patches ofreproduction. A goal should be to graduallyshift the structure of the forest towards standsof larger, more widely spaced trees.

Recommended Fire Management

Strategies

(1) The Dominican Republic has a highly pro-

fessional and effective fire suppression organi-zation. Fire suppression and fire preventionare important strategies, but applied effectivelywould be detrimental to the pine and savannaecosystems. Effective fire exclusion would ulti-mately produce conditions for larger, moredestructive fires and/or the loss of the pineand savanna ecosystems due to the loss of fireas a key ecosystem maintenance factor.

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(2) Although fire suppression and preventionare needed to prevent and reduce damage fromunwanted fires, the important role of fire inpine and savanna ecosystems needs to be rec-

ognized, and an integrated approach to firemanagement developed.

(3) What is Integrated Fire Management?Integrated Fire Management is an approach toaddressing the problems and issues posed byboth unwanted and desirable fires within thecontext of the natural environments and socio-economic systems in which they occur, by eval-uating and balancing the relative risks posed by

fire with the beneficial role that it may play in agiven conservation area, landscape or region. Itlooks for cost-effective approaches to prevent-ing unwanted fires while responding appropri-ately to those fires when they occur. It recog-nizes both the important ecological role thatfire plays in many ecosystems and the socio-economic necessity and value of using fire fortraditional and economic purposes.

(4) Develop integrated fire management plansfor key conservation areas that include:

a.Analysis of the Problem: What are theunderlying causes of unwanted fires? Where dothey occur? Why do they occur? What areasare at risk? What areas have high resource orbiodiversity values that may either be benefitedby fire or adversely affected by it? Where is fireneeded? What is the justification for managingfires in different ways?

b. Prevention: Regulate fire use, educate fireusers, enforcement, community education pro-grams. Impact mitigation: fuel reduction, vege-tation management.

c. Fire Use: Prescribed burningwhere andwhen is it needed? Where and under whatconditions can fires be allowed to run their

course or be constrained rather than sup-pressed? Develop policies that allow appropri-ate use of fire in natural areas.

d. Preparedness: Early warning and predictive

systems, detection and response systems,trained fire staff.

e. Response: Level and degree of response forgiven fire situations, and potential threats andbenefits.

f. Ecosystem Restoration and Maintenance:Environmental repair and restoration; mainte-nance of desired ecosystem structure and func-

tion; community welfare assistance.

(5) Reduce the incidence of unwanted ignitionsby:

a. Working with local agricultural communitiesto contain agricultural fires. This may involvedeveloping and disseminating educationalmaterials on controlled burning, and providingtraining and burn assistance.

b. Educate local communities so they under-stand fires role, including benefits and harm.

c. Form volunteer brigades to help suppressunwanted fires.

(6) Restore forest structure: Gradually changethe pine forests in Madre de las Aguas andSierra de Bahoruco toward a structure withlarger trees, a ground cover conducive to rela-tively low-intensity surface fires, and changesin the proportion of area burned by crowningfire to area burned by surface fire. A diversityof stand ages and structure may be needed fora variety of species. For example, the white-winged crossbill requires a habitat with maturelarge pines along with other forest structures(Latta et al. 2000).

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(7) Develop prescribed fire capability and fol-lowing a fire management plan introduce low-intensity prescribed fire at appropriate intervalsinitially in accessible areas to thin and protectdense stands and allow for survival of trees from

sapling size through pole size to mature trees.

(8) Develop a management staff (both at thereserve level and at national administrative lev-els) that is skilled in understanding fire behav-ior and making fuels assessments, using fireprediction tools, and interpreting fire effects,so they can better assess which fires need to besuppressed and which are providing ecosystembenefits, and how best to respond.

(9) Develop a management staff skilled in firesuppression and fire use, e.g., prescribed burn-ing. Ensure that they are appropriatelyequipped, including transportation.

(10) Where appropriate, use ecological forestrymethods (in conjunction with fire) to restore aforest structure less susceptible to damaging

fire, e.g., thinning, harvesting, and planting ofonly native species.

(11) Harvest, cut or kill with prescribed burnsall Caribbean pine that was planted and has

spread in Madre de las Aguas and Sierra deBahoruco. Replant or reseed only withHispaniolan pine that is from the same ecolog-ical area being restored. Dobler (1999) pro-poses a general provenance zone map for Pinusoccidentales.

(12) Aggressive reforestation efforts should notbe undertaken after most, if any fires. Theseefforts are expensive, have been using inappro-

priate species, and are frequently unsuccessful.The Hispaniolan pine has a high regenerativecapacity if seed trees are in the vicinity.Ground cover vegetation has the capacity toresprout. Pine reseeding and watershed protec-tion may be necessary when dense stands aredestroyed in crowning fires and little groundcover vegetation was there prior to the firebecause of shading.

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i. A fire response plan;

j. A fire monitoring and mapping plan;

k. A fire use plan, e.g., prescribed fire and let

burn protocol; and

l. An ecosystem restoration and maintenanceplan.

(8) Identify key individuals and opportunitiesfor training, exchanges and mentoring. TheLatin America & Caribbean Fire LearningNetwork along with the USDA Forest Servicecan facilitate training and mentoring opportu-

nities.

(9) Develop a cadre of fire managementinstructors in the Dominican Republic. Initialfocus of training and mentoring should be todevelop this instructor cadre, which can thendevelop appropriate training courses withinthe Dominican Republic.

(10) Identify a TNC or FMP staff person to

coordinate activities and actions with theGlobal Fire Initiative.

(11) Develop and/or promote a research pro-gram to address the many questions related tofire effects, fire regimes, fuels, and fire behav-ior. Important research questions include:

a. What effect does season of burn have onpine forest and savanna response? Naturallightning fires would have been common dur-ing wetter periods. Human-caused fires tendto occur earlier in the year when conditions

are drier and effects may be markedly different.

b. What are fuel accumulation rates and what isthe minimum fire return interval for maintain-ing different vegetation structures?

c. How does fire affect specific endemic or rarespecies?

d. What are the survival characteristics of pines

under different types of fire?

e. What effect do different season, frequencyand intensity of burn have on ground coverand understory structure and diversity?

f. Given the remnant nature of the pine forests,woodlands, and savannas, what are desirableoptions for applying fire over the landscape tocreate or maintain a pattern of vegetation and

habitats best suited to maintaining the biodi-versity of the area?

(12) Pursue funding to develop and implementfire projects.

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Darrow, W. K. & T. Zanoni. 1990.Hispaniolan pine (Pinus occidentalisSwartz): A little known subtropical pine ofeconomic potential. CommonwealthForestry Review 69:13346.

Dobler, Gunter. 1999. Manejo y tables derendimiento de Pinus occidentalis. SanJos de las Matas, Republica Dominicana.

Fisher-Meerow, L. L. & W. S. 1989. A floristic

study of five sites along an elevational tran-sect in the Sierra de Baoruco, Prov.Pedernales, Dominican Republic.Moscosoa 5:159185.

Guerrero, A. & M. M. McPherson. 199_ .Historia integrada de la regin de ParqueNacional Juan Bautista Prez Rancier(Valle Nuevo). Pages 2233. In:Evaluacin Ecolgica Integrada Parque

Nacional Juan Bautista Prez Rancier.

Guerrero, A., N. Ramrez, A. Veloz & B.Peguero. 199_. Vegetacin y flora delParque Nacional Juan Bautista PrezRancier (Valle Nuevo). Pages: 3456. In:Evaluacin Ecolgica Integrada ParqueNacional Juan Bautista Prez Rancier.

IUCN Species Survival Commission. 1994.

IUCN Red List. Gland, Switzerland.

Holdridge, L. R. 1947. The pine forests andadjacent mountain vegetation of Haiti,considered from the standpoint of a newclimatic classification of plant formations.Ph.D. Dissertation, University ofMichigan, Ann Arbor.

Horn, S. P., L. M. Kennedy & K. H. Orvis.2001. Vegetation recovery following ahigh elevation fire in the DominicanRepublic. Biotropica 33:701708.

Horn, S. P., K. H. Orvis, L. M. Kennedy & G.M. Clark. 2000. Prehistoric fires in thehiglands of the Dominican Republic:Evidence from charcoal in soils and sedi-ments. Caribbean Journal of Science36:1018.

Latta, S. C., M. L. Sondreal & C. Brown.2000. A hierarchical analysis of nestingand foraging habitat for the conservationof the Hispaniolan White-winged crossbill(Loxia leucoptera megaplaga ). BiologicalConservation 96:139150.

May, T. 1997. Fases tempranas de sucesin enun bosque nublado de Magnolia pallescens

despus de un incendio (Loma deCasabito, Reserva Cientfica Eban Verde,Cordillera Central, RepblicaDominicana). Moscosoa 9:117144.

McPherson, M., F. Portorreal, C. Cattafesta &F. Daz. 199_. Estudio socioeconmicode las comunidades ubicadas dentro y en laperiferia del Parque Nacional Juan BautistaPrez Rancier. In: Evaluacin Ecolgica

Integrada Parque Nacional Juan BautistaPrez Rancier.

Sherman, R. E., P. H. Martin & T. J. Fahey.2003 (submitted). Vegetation-environ-ment relationships in forest ecosystems ofthe Cordillera Central, DominicanRepublic. Journal of Tropical Ecology.

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Documents

Dominican Republic Fire Assessment