Structural resistance and functional resilience of the Chaco forest to wildland fires: an approach with MODIS time series.

LANDI MARCOS; DI BELLA C; BRAVO SANDRA; BELLIS LAURA M.

AUSTRAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2020

1442-9985

Forests have resistance thatallows them to resist fires without changing  to another state, and resilience that allows them torecover after disturbance. These properties are determined by many structuraland functional determinants that interact between them. Despite the importance of structuralresistance and functional resilience to wildland fires, few studies have evaluated thecombined effect that structural and functional determinants have on them. Our goal was toassess the structural resistance and functional resilience to fire using remote sensinginformation. We specifically assessed the combined effect of pre-fire vegetationcharacteristics, burn severity, and post-fire precipitation on forest structuralresistance and functional resilience to fire. Eighty five forest plots of 250 mx 250 m were selected in areas that burned in 2003. For each burned plot, apaired unburned control plot of 250 m x 250 m was selected outside the burnedareas. We measured burn severity and post-fire precipitations  (2004-2011). We analyzed MODIS time series in order tocalculate the following pre (2002) and post-fire (2011) phenological parameters:minimum level of photosynthetic  activityper year; maximum level of photosynthetic activity per year; length of growing seasonper year; integral of annual photosynthetic activity; relative seasonality of  photosynthetic activity. Also we detected plots thatchanged into a shrubland eight years after the fire. Fifty three percent of burned plotschanged from forest into a shrubland state. Results show that the forest structuralresistance to fire depends on the balance between the level of severity and the parameters relatedto pre-fire aboveground net primary production. The impact of pre-fire vegetationcharacteristics on functional resilience ability was driven by burn severity andit?s interactions with pre-fire productivity and seasonality. Results suggest thatchanges in forest species composition and aboveground net primary production reduced foreststructural resistance and functional resilience to fire