Notes: Significance levels of regression: ***p < 0.001, **p
< 0.01, *p < 0.05, and †p < 0.1.
Compared to ignition source and fire weather, fuel composition and
topography did not strongly impact tundra fire occurrence (Figure 2
a-b). Logistic regressions suggested that fractional covers of woody and
herbaceous components were positively related to the fire occurrences
(Table 1). Fires in the North Slope and the Seward Peninsula tended to
occur in regions with more woody fuels. In contrast, those in Southwest
Alaska show the opposite (Figure S6). Significantly higher coverage of
nonvascular fuels was found when fires occurred in Southwest Alaska,
while an inverse relationship existed for fires in the North Slope
(Table S4). The significantly negative relationship between elevation
fire occurrence (Table 1) also suggests that tundra fires are more
common in flat areas.