Fire is treated as uniformly destructive, and a large number of ecosystems depend on it. Distinguishing the two situations is essential to managing either.
Fire-adapted systems
Many ecosystems experienced regular fire for millennia and their species are adapted to it.
Thick bark protecting the cambium. Resprouting from underground structures. Seeds requiring heat or smoke to germinate. Cones opening only after fire.
Which means fire in these systems is a natural process, and its absence is the disturbance.
The suppression consequence
Decades of fire exclusion allowed fuel to accumulate in systems that previously burned frequently at low intensity.
Which converts a regime of frequent low-intensity fire into one of infrequent high-intensity fire.
The second kills mature trees that the first did not, which changes the system fundamentally.
This is well documented and is the basis for reintroducing managed fire in many regions.
Prescribed burning
Deliberate low-intensity fire under controlled conditions to reduce fuel and maintain habitat.
Which has strong evidence for reducing subsequent wildfire severity, and it faces obstacles including smoke, liability, narrow weather windows and public opposition.
The area treated is consistently far below what assessments identify as needed.
Indigenous fire management
Sophisticated fire practices developed over millennia in several regions, using frequent small burns at specific times.
Which produced landscape mosaics with varied fire histories, supporting diversity and limiting large fires.
These practices were suppressed under colonial administration, and their reintroduction is now actively pursued in several countries with documented benefits.
Systems where fire is destructive
Tropical rainforest, which does not naturally burn and where fire follows drying from logging and drainage.
Peatlands, where fire consumes accumulated carbon and can burn underground for months.
And systems where fire frequency has increased beyond what species can recover from, which is occurring in several regions.
The interval question
Species adapted to fire require time between fires to reach reproductive maturity and rebuild seed stores.
Which means fires occurring too frequently eliminate them just as effectively as no fire at all.
Interval shortening due to changing climate and to human ignition is a documented threat in several fire-adapted systems.
Climate effects
Fire weather — hot, dry, windy conditions — has increased in frequency and duration in many regions.
Which extends fire seasons and increases the proportion of fires that become large.
Attribution studies have linked specific extreme fire seasons to changed conditions with varying confidence.
The wildland interface
Where development meets vegetation, which is where most fire damage to property occurs.
Expansion of building into fire-prone landscapes has increased exposure substantially.
Which means much of the damage attributed to changed fire behaviour also reflects changed exposure.
Building materials, defensible space and community planning all have evidence behind them and are inconsistently required.
After fire
Post-fire salvage logging has been found in several studies to impede recovery, by removing structure and disturbing regenerating soil.
Standing dead trees provide habitat for a distinctive set of species that depend on burned forest.
Which means a burned forest is a habitat rather than a wasteland, and treating recovery as requiring intervention is frequently wrong.
Smoke
A health consequence receiving increasing attention.
Wildfire smoke affects air quality over very large areas, and health effects have been documented at considerable distance from fires.
Which is a factor in prescribed burning decisions, since managed fire also produces smoke, generally less and at controlled times.
Fire and invasive grasses
A feedback that has transformed several regions.
Invasive grasses produce fine continuous fuel, increasing fire frequency.
The grasses recover faster than native vegetation, which increases their dominance, which increases fire frequency further.
Which converts shrubland and woodland to grassland permanently, and it is very difficult to reverse.
Recovery monitoring
Satellite data allows burned area and severity to be mapped consistently.
Which has produced global records of fire extent over decades, revealing that total burned area has declined globally while severe fire in forested regions has increased.
That distinction is frequently lost in coverage, and both parts are established.
Firefighting and ecology
Suppression tactics have ecological consequences.
Fire retardant affects water quality and vegetation. Containment lines cut through habitat and create access routes.
Which is weighed against protecting life and property, and the balance has shifted toward allowing some fires to burn where they are not threatening either.
Post-fire wildlife
Burned areas support a distinctive community, including species that specialise in recently burned habitat.
Woodpeckers, certain beetles and specific plants depend on it.
Which means uniformly preventing or salvaging fire removes a habitat type entirely.
Fire and grazing
Grazing removes fuel, which affects fire behaviour.
Which is used deliberately in some management systems and produces its own vegetation effects.
The interaction between fire and grazing shapes many grassland and savanna systems, and managing one without the other rarely produces the intended result.
Which means management decisions require knowing which regime a system evolved under, and that knowledge is patchy for many places.