Climate change and fire suppression: Drivers of fire regimes at actionable scales

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The relative influence of climate change and fire exclusion vary with soil moisture, which itself is influenced by climate and local topography:

• Burn probability along a soil aridity gradient for Trail Creek and Johnson Creek, with and without climate change, and with and without fire exclusion. Climate change increased burn probability by drying fuels in the most mesic locations (i.e., locations where temporally averaged soil moisture was high; see difference between blue and orange lines, highlighted by the upward pointing arrow). In the most arid locations, climate change promoted drought stress and reduced fine fuel loads, which in turn reduced burn probability.
• Climate change increased burn probability and led to larger, more frequent fires in locations where soil aridity was relatively low (i.e., time-averaged soil moisture >35%).
• In the most arid locations (i.e., time-averaged soil moisture <25%), climate change promoted drought stress and reduced fine fuel loads, which in turn reduced burn probability.
• In locations with intermediate soil aridity (25-35%), the effects of climate change and fire suppression varied in response to local trade-offs between aridity (which makes fuels more flammable) and productivity (which increases fuel loads).

Even within watersheds, at fine scales, risk management must be spatially and temporally explicit to optimize effects