Non-linear ecological processes, fires, environmental heterogeneity and shrub invasion in northwestern Patagonia

Studying the post-fire performance of tussock grasses in Patagonia: Survival, biomass production and early competition

“…The La Niña phase leads to warmer and drier springs in Patagonia, exacerbating drying of fuel, which at the time is associated with large wildfires (Ghermandi et al, 2010;Veblen and Kitzberger, 2002). In January 1999, after an extreme drought related to strong ENSO events, a fire ignited by two lighting strikes burning 17.500 ha (60%) of the San Ramón Ranch (Ayesa, 1999;Ghermandi et al, 2004).…”

Are Fabiana imbricata shrublands advancing over northwestern Patagonian grasslands? A population dynamics study involving fire and precipitation

“…Given that F. imbricata is unpalatable, environmental value as a production unit might diminish because of its advance. Several previous studies suggest that fire can promote shrub invasion in the Patagonian steppe (Franzese et al, 2009;Ghermandi et al, 2004Ghermandi et al, , 2010Gonzalez et al, 2010). In early post-fire succession, new encroachment foci of F. imbricata were observed (Ghermandi et al, 2004).…”

“…Plants show variable responses to these variations which regulate their population dynamics. Many species are stimulated by fire, which increases their germination and seedling recruitment (Bond and van Wilgen, 1996;Franzese et al, 2009;Ghermandi et al, 2004Ghermandi et al, , 2010Pausas et al, 1999) to the point that, for some species, reproduction has a forced dependence on fire and they can be driven to extinction by fire suppression (Bond and van Wilgen, 1996).…”

Spatial dynamics of <I>Fabiana imbricata</I> shrublands in northwestern Patagonia in relation to natural fires

“…Regarding this, we believe that this pattern is generated by the hydric dispersion of the seeds -as they are extremely small and without appendices and, therefore, they are not disseminated by the wind to farther distances. The post-fire recruitment of new F. imbricata individuals occurs when there is a wet spring after a fire (Ghermandi et al, 2010); accordingly, and as a consequence of the hydric conditions of soil bordering the streams, this species could generate corridors like those normally seen in the area under study. Therefore, it is an important fact to take into account, as the dispersion has shown to be an essential factor in the spatial structure of communities (Heinz et al, 2005).…”

“…This obligate seeder species recruits new individuals after a disturbance (Ghermandi et al, 2010) forming coeataneous shrublands (Ruete, 2006). According to this, high rates of F. imbricata recruitment were detected after a severe fire followed by a wet spring and models suggest that this is the best situation for the growth of F. imbricata shrublands, also at different fire frequencies (Ghermandi et al, 2010). Global climate change models suggest an in- crease in the frequency and amplitude of the ENSO phenomena and for this more recruitment windows could be expected for F. imbricata.…”