Threats and Strategies for Global Biodiversity Conservation

In order to craft effective strategies,conservation organizations andpartners need to understand ecosystemand human relationships to fire.Altered fire regimes can change the species composition,structure and fire characteristics in any ecosystem.To effectively conserve biodiversity, we need tounderstand not only how fire naturally behaves inecosystems, but also how people use or alter nativefire regimes for ecological and social benefit. Certainhuman land uses can alter the healthy functioningof fire in any ecosystem type—whether it befire-dependent, fire-sensitive or fire-independent.For example, rural development in fire-dependentecosystems often brings with it suppression of all fireincidents—natural and human-caused—to protecthuman communities. Rural development in fire-sensitiveecosystems may have a different impact. Housing andinfrastructure development is often followed byhuman-caused fires that require fire prevention orsuppression for the sake of biodiversity conservation.In order to craft effective strategies, conservationorganizations and partners need to understandecosystem and human relationships to fire.An Australian aborigine uses fire as a land management tool in Arnhem Land,Northern Territory, Australia. People around the world have legitimate reasonsfor starting fires, and many cultures have gained an intimate knowledge of firebehavior, having used fire as a tool for centuries. © Penny Tweedie/CORBISBox 3. Fire’s Ecological RoleEcosystems can be classified in terms of their relationshipto fire regime characteristics such as fuels, flammability,ignitions, and fire spread conditions.Fire-dependent ecosystems are those where most of thespecies have evolved in the presence of fire, and wherefire is an essential process for conserving biodiversity(e.g., savannas, temperate coniferous forests). Excludingfire from these systems, or introducing ecologicallyinappropriatefire—at inappropriate frequency, severityor seasonal timing—can substantially alter these systems.Fire-sensitive ecosystems are those where most of thespecies have not largely evolved in the presence of fire.While fire may play a secondary role in maintainingnatural ecosystem structure and function in fire-sensitivesystems, the introduction of ecologically-inappropriatefire can have an extensive negative impact on biodiversity(e.g., tropical moist broadleaf forests). Too much fire infire-sensitive forests can also create a negative feedbackloop, making these forests more susceptible to fire inthe future, and rapidly degrading the most intact forestecosystems.Fire-independent ecosystems are those that naturallylack sufficient fuel or ignition sources to support fireas an evolutionary force (e.g., deserts, tundra).Fire-dependent, -sensitive and -independent ecosystemscan be further classified in terms of their condition. Forexample, through human land uses, even fire-independentsystems can experience more fire than would haveoccurred naturally through the introduction of invasiveexotic species, or excessive human-caused ignitions.Intact fire regimes are those that have fire regimecharacteristics (e.g., fire frequency, severity, extent,and season) within their range of natural variability.Degraded fire regime conditions are those that areconsidered by experts to be outside their range ofnatural variation, but are considered restorable.Very degraded fire regime conditions are those faroutside their natural range of variability, and maynot be restorable.4