ecological restoration or community protection. Socialtransmigration schemes, whereby villages or communitiesare moved from one location to another <strong>for</strong> rural developmentpurposes, can also pose a threat to fire regimes.Often, transplanted communities lack familiarity withtheir new environment <strong>and</strong> the l<strong>and</strong> <strong>and</strong> fire uses thatcan be sustained there. Combined with a lack of underst<strong>and</strong>ingof local fire ecology, this can lead to a loss of thenatural fire regime. For instance, colonization of thetemperate <strong>for</strong>ests of Mexico’s Sierra Madre Occidentalled to a drastic decrease in fire frequency in the early tomid 1900s (Heyerdahl <strong>and</strong> Alvarado 2003). More recently,extensive colonization of the Brazilian Amazon <strong>for</strong>estcreated a massive fire problem that is threatening thesustainability of one of the most biodiverse biomes(Cochrane 2002).Livestock Farming, Ranching <strong>and</strong> AgricultureModern <strong>and</strong> traditional grazing <strong>and</strong> ranching practices arean exp<strong>and</strong>ing threat to biodiversity worldwide, particularlywhere food security is a global priority. These practiceshave altered fire regimes across the vast majority of majorhabitat types worldwide (12 of 14), <strong>and</strong> affect almost 25%of all terrestrial ecoregions assessed. In fire-dependentecosystems, such as temperate, tropical <strong>and</strong> subtropicalgrassl<strong>and</strong>s, savannas, <strong>and</strong> shrubl<strong>and</strong>s, livestock farming<strong>and</strong> ranching can reduce fuel levels, connectivity <strong>and</strong>patchiness, <strong>and</strong> thus the ability of an ecosystem to carryfire on a large scale, or can cause too much fire dueto annual firing of grasses to rejuvenate them.Agriculture is a top global source of threat to biodiversityoverall, <strong>and</strong> alters fire regimes in at least 30% of allecoregions worldwide (<strong>and</strong> 12 of 14 major habitat types).Major habitat types particularly at risk include tropical <strong>and</strong>subtropical dry broadleaf <strong>for</strong>ests; tropical <strong>and</strong> subtropicalgrassl<strong>and</strong>s, savannas <strong>and</strong> shrubl<strong>and</strong>s; tropical <strong>and</strong> subtropicalmoist broadleaf <strong>for</strong>ests; <strong>and</strong> flooded grassl<strong>and</strong>s <strong>and</strong>savannas. In tropical areas, large areas of peat swamp<strong>for</strong>est have been converted to agricultural l<strong>and</strong>. Thisresults in altered drainage patterns leading to degradedpeat swamp <strong>for</strong>ests <strong>and</strong> high fire risk.Slash <strong>and</strong> burn shifting agriculture <strong>and</strong> ranching are predominantpractices in many parts of the developing world,<strong>and</strong> a way of life <strong>for</strong> many people. In fire-sensitive systems,such as tropical <strong>and</strong> subtropical dry <strong>and</strong> moist broadleaf<strong>for</strong>ests, ecologically-inappropriate fire use <strong>for</strong> l<strong>and</strong> clearing,<strong>for</strong>age management, <strong>and</strong> shifting agriculture leads to directconversion of habitat. When fires escape, adjacent <strong>for</strong>estsare also impacted. The environmental degradation thatresults from poor fire management practices can trap localpeople in a “poverty cycle,” where poverty leads to environmentaldegradation, which then reduces the capacity ofecosystems to sustain human livelihoods.Fire <strong>and</strong> Fire SuppressionFire regimes in almost all major habitat types (13 of 14)are threatened by ecologically-inappropriate humanintroduction of fire or fire suppression. Over 20% of allterrestrial ecoregions assessed experience altered fire regimesthrough direct fire suppression or human-caused ignitionsoutside the range of natural variation. Across fire-dependenthabitats, fire suppression to protect human values not onlydirectly alters fire regimes, but can also lead to furtherdegradation from increased <strong>for</strong>est <strong>and</strong> shrub densities, lossof fire-adapted species, increases in fire-sensitive species,<strong>and</strong> uncharacteristic fire behavior when fires escapesuppression <strong>for</strong>ces.ThreatLivestock Farming <strong>and</strong> RanchingEnergy Production <strong>and</strong> MiningFire <strong>and</strong> Fire SuppressionRural <strong>and</strong> Urban DevelopmentAgricultureConflicts with Traditional Fire UseClimate ChangeLogging <strong>and</strong> Wood HarvestingTransportation InfrastructureInvasive SpeciesRecreational ActivitiesGathering Terrestrial PlantsDams <strong>and</strong> Water Management UseWood <strong>and</strong> Pulp PlantationsRealmAustralasia Indo-Malay Nearctic Neotropic10Table 1. Top sources of threats to restoring <strong>and</strong>maintaining the ecological role of fire by realmassessed during realm-level expert workshopsJanuary-July 2006.
A United Nations analysis of national fire policies in 1998concluded that fire mitigation policies were generallyweak, <strong>and</strong> were rarely based on reliable data of <strong>for</strong>est fireextent, causes or risks (ECE/FAO 1998). Inadequate<strong>for</strong>est management policies are often incompatible withbiodiversity conservation, particularly policies aimed attotal fire exclusion in fire-dependent ecosystems, whichcan lead to fuel accumulation <strong>and</strong> catastrophic fire outbreaks(Hassan et al. 2005). Public policies that ban orseverely limit burning can also put people at risk ofbreaking laws when their intentions are to maintainecological processes <strong>and</strong> traditional cultures. Intentional<strong>and</strong> unintentional human-caused ignitions, where there islittle fire management capacity to prevent or suppress them,degrade the ecological sustainability of fire-sensitive <strong>and</strong>fire-independent ecosystems by increasing their vulnerabilityto invasive species <strong>and</strong> future fires.Resource ExtractionFire regimes in more than 13% of all terrestrial ecoregionsassessed (<strong>and</strong> 12 of 14 major habitat types) are consideredto be altered by energy production <strong>and</strong> mining. Energyproduction <strong>and</strong> mining is an exp<strong>and</strong>ing threat worldwideas development increases <strong>and</strong> global energy markets shift.Transportation infrastructures <strong>for</strong> energy <strong>and</strong> miningoperations—roads, powerlines, pipelines, railroads—act asa conduit <strong>for</strong> both invasive species <strong>and</strong> increased humancausedfire ignitions in fire-dependent, fire-independent<strong>and</strong> fire-sensitive ecosystems. The alteration of fire regimesat this “development frontier” has exponentially greaterconsequences <strong>for</strong> biodiversity in fire-sensitive systems,where the area of fire spread <strong>and</strong> de<strong>for</strong>estation can bemuch greater than the area impacted by the energy <strong>and</strong>mining operations themselves.In addition, fire regimes in over 3% of all terrestrial ecoregionsassessed (<strong>and</strong> seven of 14 major habitat types) areconsidered to be altered by logging <strong>and</strong> wood harvesting.Logging <strong>and</strong> wood harvesting are of particular concernrelative to their alteration of fire regimes in the Indo-Malay, Nearctic <strong>and</strong> Neotropic realms (Table 1). Logging<strong>and</strong> wood harvesting can be a direct source of threatthrough human-caused ignitions, or through the indirecteffect of altering fuels <strong>and</strong> moisture conditions thatencourage “too much” fire. “Too little” fire, in terms of number<strong>and</strong> severity, may also result from fuelwood collection<strong>for</strong> domestic use by rural communities. Modification offuelbed structure can also reduce crown fires where theyare part of the natural regime. Forest certification strategiesthat aim to ensure ecologically sustainable logging <strong>and</strong>wood harvesting practices can be greatly improved byincluding the need <strong>for</strong> fire in fire-dependent ecosystems,<strong>and</strong> need <strong>for</strong> fire suppression, mitigation <strong>and</strong> prevention infire-sensitive <strong>and</strong> fire-independent ecosystems.Logging alters fire regimes in <strong>for</strong>ests around the globe when it creates<strong>for</strong>est structures or fuel loads that are inconsistent with the natural fireregime. The Nature Conservancy <strong>and</strong> partners are working in this <strong>for</strong>estin Chiapas, Mexico to improve management practices <strong>and</strong> mitigate theeffects of logging on fire regimes. © Mark GodfreyClimate ChangeFire experts identified climate change as a potential causeof fire-related threats to biodiversity in 4% of all ecoregionsworldwide <strong>and</strong> 12 of 14 major habitat types. Regionalexpert workshops, however, revealed a range in judgmentof the relative importance of climate change compared toother sources; the actual importance of climate change inaltering fire regimes may likely exceed the expert ranking.Generally, in fire-dependent systems where the ecologicallyappropriatefire regime is intact, there should be no netloss of stored carbon because the biomass that burnsregrows over the life of the fire cycle. However, climatechange is increasing fire frequency <strong>and</strong> extent by alteringthe key factors that control fire: temperature, precipitation,humidity, wind, ignition, biomass, dead organic matter,vegetation species composition <strong>and</strong> structure, <strong>and</strong> soilmoisture (IPCC 2001). These changes threaten properecosystem function <strong>and</strong> the provision of ecosystem services(Hassan et al. 2005, IPCC 2001, Turner et al. 1997).Warmer temperatures, decreased precipitation over l<strong>and</strong>,increased convective activity, increases in st<strong>and</strong>ing biomassdue to CO2 fertilization, increased fuels from dyingvegetation, <strong>and</strong> large-scale vegetation shifts comprisethe most significant mechanisms through which globalwarming increases fire at the global scale. In the case offires larger than 400 hectares in mid-altitude, federallymanagedconifer <strong>for</strong>ests of the western U.S., an increasein spring <strong>and</strong> summer temperatures of 1˚C since 1970,earlier snowmelt, <strong>and</strong> longer summers have increased firefrequency 400% <strong>and</strong> burned area 650% in the period 1970-2003 (Westerling et al. 2006). The low level of humanactivity or fire exclusion in those <strong>for</strong>ests, however, impliesthat climate change may cause different impacts in areas ofintense human intervention.11