Assessment

* Fire-Alternative Views

* Careless and Indiscriminate Fire Use

Strategies

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Ecological Functions of Fire Fire is a natural evolutionary force that has influenced Sierran ecosystems for millennia, influencing biodiversity, plant reproduction, vegetation development, insect outbreak and disease cycles, wildlife habitat relationships, soil functions and nutrient cycling, gene flow, selection, and, ultimately, sustainability.

Effects of Climate Climatic variation plays an important role in influencing fire patterns and severity; fires have been most extensive in periods of dry years.

Presettlement Fire Regimes In most lower-elevation oak woodland and conifer forest types of the Sierra Nevada, presettlement fires were frequent, collectively covered large areas, burned for months at a time, and, although primarily low to moderate in intensity, exhibited complex patterns of severity.

Effects of Suppression Fire suppression in concert with changing land-use practices has dramatically changed the fire regimes of the Sierra Nevada and thereby altered ecological structures and functions in Sierran plant communities.

Fuel Conditions Live and dead fuels in todays conifer forests are more abundant and continuous than in the past.

Effects of Logging Timber harvest, through its effects on forest structure, local microclimate, and fuel accumulation, has increased fire severity more than any other recent human activity.

Fire Size Trends The commonly expected consequence of decades of fire suppressionthat large, infrequent fires are becoming larger and small, frequent fires smalleris generally not confirmed by records for twentieth-century Sierran forests.

Fire Surrogates Although silvicultural treatments can mimic the effects of fire on structural patterns of woody vegetation, virtually no data exist on the ability to mimic ecological functions of natural fire.

Urban-Wildlands Intermix Projected trends in urban settlementhomes intermixed with flammable wildlandsplace an increasing number of homes and people at high risk of loss from wildfire unless hazards are mitigated.

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