Human-driven temporal shifts in fire activity: southwest Russia and north Australia as case study regions

Abstract:

Decadal trends in fire activity can reveal important human and climate-driven influences across a multitude of landscapes from croplands to savannas. We use 16 years of daily satellite observations from 2003-2018 to search globally for stationary temporal shifts in fire activity during the primary burning season. Pinpointing regions where such shifts in the fire season occur is critical for interpreting broader changes in agricultural systems, fire management practices, and government policies. We focus on southwest Russia and north Australia as case study regions; both regions experienced nearly 40-day shifts in peak burning time over a 16-year period but in opposite directions. In southwest Russia, a major wheat-growing region, we trace the delay in post-harvest fires to a combination of factors including modernization in the agricultural system, recent droughts, and government restrictions on wheat exports. In north Australia, prescribed burns in the early dry season are a key practice in Aboriginal fire management, and the increasing trend of such fires has limited the size and extent of fast-spreading late dry season fires, thereby shifting overall fire activity earlier. We find that human action is the dominant driver of temporal shifts in fire activity with climate as both a harbinger and an amplifier of human-induced changes in both agricultural systems and savanna, grassland, and shrubland ecosystems.