Post-fire recovery occurs overwhelmingly by resprouting in the Chaco Serrano forest of Central Argentina

Abstract

In fire-prone landscapes, differences in post-fire regeneration by resprouting between species or sites could be far more important in explaining vegetation physiognomy and composition than seed regeneration. This is the first study exploring the relative contribution of tree resprouts and seeds to post-fire crown volume in the Chaco Serrano forest of South America. Additionally, we compare the resprouting response among species and quantify post-fire changes in tree composition among sites.We established 290 permanent plots distributed in three sites affected by wildfires in 2005. For all tree species in all plots we recorded survival of every individual 1 year after the fire; at the plot level, we recorded the above-ground tree volume before and 3 years after the fire. Resprouting from the base was the main resprouting type. Survival varied between species from 73% to 100% for native species and from 7% to 100% for non-natives. Before the fire, crown volume was similar in the three sites, and was completely lost after the fire in 92% of the plots. Three years after the fire, between 8% and 58% of crown volume was recovered. The ratio of crown recovery because of resprouts and seedlings was 1562:1. Tree composition exhibited few changes because of the high post-fire survival of most native species.We conclude that in the semiarid Chaco Serrano ecosystem tree species regenerate mainly by resprouting. This regeneration mode should be taken into account to better understand post-fire successional pathways of these forests, their management and the restoration of burnt forest areas.

Do Wildfires Promote Woody Species Invasion in a Fire-Adapted Ecosystem? Post-fire Resprouting of Native and Non-native Woody Plants in Central Argentina

“…The long-term evolutionary history of fire regimes are unknown in the Chaco Serrano but a long history of disturbances such as fire and herbivory is presumed on the basis that most trees survive these disturbances very well by resprouting (Bellingham and Sparrow 2000;Bond and Midgley 2001;Gurvich et al 2005;Torres et al 2014). However, debate exist to the extent that resprouting is an adaptation to fire and not to other disturbances because a low proportion of Chaco species have seeds whose germination is enhanced by heat, albeit most species tolerate heat (Jaureguiberry and Díaz 2015).…”

“…The effect of fire on plant communities invaded by nonnative invasive plants has gone almost unstudied in the South American Gran Chaco, the second largest biome of South America, where fires are frequent and resprouter woody plants dominate the system (Gurvich et al 2005;Verzino et al 2005;Torres et al 2014;Bravo et al 2014). Here, we study the post-fire resprouting response of native and non-native species in Chaco Serrano forest of central Argentina.…”

“…In this work, we assumed a long fire history in our study region according some antecedents within other mountain ecosystems of Argentine North region with a dry season (Grau and Veblen 2000;Aráoz and Grau 2010) and because in our study region all woody plants resprout after fires albeit resprouting is not necessarily an adaptation to fires (Gurvich et al 2005;Torres et al 2014). Considering the diverse geographical origins of non-native species, our hypothesis is that native woody species would respond to fires relatively better as compared to non-native woody species which should present a greater diversity of responses to fire.…”

Cambios florísticos inducidos por la frecuencia de fuego en el Chaco Serrano.

“…Por otro lado, una disminución de la diversidad vegetal ha sido reportada en pastizales templados (Collins et al, 1995;Li et al, 2013), bosques y sabanas tropicales a altas frecuencias de fuego (Nayak et al, 2014). Si bien existen estudios sobre los efectos del fuego en la vegetación del Chaco Serrano (Verzino et al, 2005;Giorgis et al, 2013;Torres et al, 2014), hasta el momento no se ha evaluado cómo las elevadas frecuencias de fuego actuales afectan la diversidad y composición de la comunidad de plantas en esta ecoregión.…”

“…En este sistema montañoso, la principal estrategia de regeneración post-fuego de las plantas leñosas es el rebrote, presentando alta supervivencia y rápida recuperación de su biomasa después del fuego (Torres et al, 2014;Herrero et al, 2016). En efecto, se ha sugerido que comunidades dominadas por especies de plantas rebrotadoras mostrarían poco cambio de la composición de especies después de la ocurrencia de un incendio (Bond & Midgley, 2001).…”