Data from: Influences of fire–vegetation feedbacks and post-fire recovery rates on forest landscape vulnerability to altered fire regimes

1. In the context of on-going climatic warming, forest landscapes face
increasing risk of conversion to non-forest vegetation through alteration
of their fire regimes and their post-fire recovery dynamics. However, this
pressure could be amplified or dampened, depending on how fire-driven
changes to vegetation feed back to alter the extent or behavior of
subsequent fires. 2. Here we develop a mathematical model to formalize
understanding of how fire–vegetation feedbacks and the time to forest
recovery following high-severity (i.e., stand-replacing) fire affect the
extent and stability of forest cover across landscapes facing altered fire
regimes. We evaluate responses to increasing burn rates while varying the
direction (negative vs. positive) of fire–vegetation feedbacks under a
continuum of values for feedback strength and post-fire recovery time to
determine how interactions among these variables produce thresholds and
tipping points in landscape responses to changing fire regimes. 3. Where
the early-seral vegetation is less fire-prone than older forests, negative
feedbacks limited the reductions in forest cover in response to increased
fire frequency or slower forest recovery. By contrast, positive feedbacks
(more flammable early-seral vegetation) produced a tipping point beyond
which increased burn rates or slower forest recovery drove extensive
forest loss. 4. With negative feedbacks, the rates of forest loss and
expansion in response to variation in fire frequency were similar.
However, where feedbacks are positive, the conversion from predominantly
forested to non-forested conditions in response to increased fire
frequency was faster than the re-expansion of forest cover following a
return to the initial burn rate. Strengthening the positive feedbacks
increased this asymmetry. 5. Synthesis. Our analyses elucidate how
fire–vegetation feedbacks and post-fire recovery rates interact to affect
the trajectories and rates of landscape response to altered fire regimes.
We illustrate the vulnerability of ecosystems with positive
fire–vegetation feedbacks to climate change-driven increases in fire
activity, especially where post-fire recovery is slow. Although negative
feedbacks initially provide resistance to forest loss with increasing burn
rates, this resistance is eventually overwhelmed with sufficient increases
to burn rates relative to recovery times.