Here we used SEA to decipher the behavioral responses of the main functional subalpine species to fire over the past 8000 years, assuming that assemblages of sedimentary plant macroremains provide evidence of the local composition of plant species, and that influxes of macroremains provide information on changes in the biomass of species present in the lake surroundings.
We propose the following aspen fire regime types: (1) fire-independent, stable aspen; (2) fire-influenced, stable aspen; (3) fire-dependent, seral, conifer-aspen mix; (4) fire-dependent, seral, montane aspen-conifer; and (5) fire-dependent, seral, subalpine aspen-conifer.
Only for Douglas-fir and subalpine fir does a shorter fire rotation temporally reveal this tension, especially at year 2060, by killing trees in newly unsuitable locations and increasing overall favorability values.
The opposite trend occurred under current climate and the future fire regime, as subalpine fir and Douglas-fir generally decreased in area over time, while ponderosa pine and lodgepole pine increased (though only slightly and temporarily for the latter species).
We specifically assessed the projected future redistribution of four of the most dominant and well-distributed tree species in the region (Douglas-fir, lodgepole pine, ponderosa pine, and subalpine fir) to determine how fire might influence shifts in species ranges under climate change.
In subalpine ecosystems during the Holocene, fire promoted a typical pattern of secondary succession (Figure 3) as predicted by the Eggler's initial floristic model [42].
Furthermore, recent dendrochronological studies of burned stands of mixed Larix decidua-Pinus cembra within the subalpine belt failed to discover fire scars on old-growth Larix decidua [29], suggesting that the thick bark of Larix prevents mature trees from suffering cambial damage due to fire [30].
In only a few cases did fire appreciably affect trends in favorability values, including Douglas-fir, for which the favorability of occupied sites under the future fire regime was higher than other fire scenarios at 2060, and subalpine fir, for which the favorability ranges (but not means) of occupied sites noticeably varied among fire regimes for both 2030 and 2060.
In addition, EMBYR was used to explore fire patterns in the subalpine plateau by simulating four scenarios of weather and fuel conditions.
Ninety-nine study plots were examined across a gradient of interaction severities from a 1997 blowdown, subsequent salvage logging, and a 2002 fire in a Rocky Mountain subalpine forest.
