Can wildland fire management alter 21st-century subalpine fire and forests in Grand Teton National Park, Wyoming, USA

In subalpine forests of the western United States that historically
experienced infrequent, high-severity fire, whether fire management
can shape 21st-century fire regimes and forest dynamics to meet
natural resource objectives is not known. Managed wildfire use (i.e.,
allowing lightning-ignited fires to burn when risk is low instead of
suppressing them) is one approach for maintaining natural fire regimes
and fostering mosaics of forest structure, stand age, and tree-species
composition, while protecting people and property. However, little
guidance exists for where and when this strategy may be effective with
climate change. We simulated most of the contiguous forest in Grand
Teton National Park, WY to ask: (1) How would subalpine fires and
forest structure be different if fires had not been suppressed during
the last three decades? (2) What is the relative influence of climate
change versus fire management strategy on future fire and forests? We
contrasted fire and forests from 1989-2098 under two fire management
scenarios (managed wildfire use and fire suppression), two general
circulation models (CNRM-CM5 and GFDL-ESM2M), and two representative
concentration pathways (8.5 and 4.5). We found little difference
between management scenarios in the number, size, or severity of fires
during the last three decades. With 21st-century warming, fire
activity increased rapidly, particularly after 2050, and followed
nearly identical trajectories in both management scenarios. Area
burned per year between 2018-2099 was 1,700% greater than in the last
three decades (1989-2017). Large areas of forest were abruptly lost;
only 65% of the original 40,178 ha of forest remained by 2098.
However, forests stayed connected and fuels were abundant enough to
support profound increases in burning through this century. Our
results indicate that strategies emphasizing managed wildfire use,
rather than suppression, will not alter climate-induced changes to
fire and forests in subalpine landscapes of western North America.
This suggests that managers may continue to have flexibility to
strategically suppress subalpine fires without concern for long-term
consequences, in distinct contrast with dry conifer forests of the
Rocky Mountains and mixed conifer forest of California where
maintaining low fuel loads is essential for sustaining frequent,
low-severity surface fire regimes.