Postfire responses of the woody flora of Central Chile: Insights from a germination experiment

Abstract

Fire is a selective agent shaping plant traits and community assembly in fire-prone ecosystems. However, in ecosystems with no fire history, it can be a cause of land degradation when it is suddenly introduced by humans, as plant species may not be able to respond to such novel disturbance. Unlike other Mediterranean-type ecosystems (MTE) of the world, natural fires have not been frequent during the Quaternary in the matorral of Central Chile, and thus, plant adaptive responses are expected to be uncommon. We evaluated the effect of heat shock on seed survival and germination of 21 native woody plants of the Chilean matorral and compiled information on smoke-stimulation and resprouting, to evaluate the importance of fire-adaptive responses in the context of the other MTE. We found that in the Chilean woody flora negative seed responses to fire cues were more frequent than positive responses. Although resprouting is a relatively widespread trait, fire-stimulated germination is not as common in the Chilean matorral as in other MTE. The seeds of seven endemic species were strongly damaged by fire cues and this should be considered in post-fire restoration planning. However, our results also showed that many species were resistant to elevated doses of heat shock and in some, germination was even stimulated. Thus, future research should focus on the evolutionary causes of these responses. These findings could help to develop strategies for fire management in the Chilean matorral. In addition, they will improve our understanding of the evolutionary forces that shaped this plant community and to better frame this region among the other MTE worldwide.

Fire and legume germination in a tropical savanna: ecological and historical factors

“…A lack of fire-stimulated germination has also been shown for fire-prone Brazilian subtropical grasslands, the Argentinean Chaco and the Chilean matorral (Overbeck et al, 2006;Jaureguiberry and Díaz, 2015;Fidelis et al, 2016;Gómez-González et al, 2017). Irrespective of germination, seed traits were important predictors of seed mortality under the hottest treatment.…”

Evolutionary history of fire‐stimulated resprouting, flowering, seed release and germination

“…. Heat tolerance is under genetic control and there is a case for considering this as a nil/weak/strong fire response independent of subsequent effects on resprouting, flowering, and seed release and germination, but it has rarely been recognized as a fire‐adapted trait in its own right (Paula & Pausas, ; Gómez‐González et al, ).…”

Fire and Plant Diversification in Mediterranean-Climate Regions

“…Nevertheless, many fire regimes accommodate both fire-response types and their co-existence is common ( Groeneveld et al, 2013 ; Vilagrosa et al, 2014 ). In central Chile, many woody species resprout well after anthropogenic fires ( Donoso Zegers, 2006 ; Gómez-González et al, 2017 ), possibly reflecting an Oligocene or early Miocene history when their lineages would have been subject to more frequent fire before the uplift of the Andes.…”

“…At the generic level, canopy seed storage is common in southwestern Australia and the Cape Region, but uncommon in the Mediterranean Basin and California and virtually absent in central Chile. In central Chile, where serotiny has not developed, soil seed storage in woody plants is transient or short but is longer in some Fabaceae and Rhamnaceae with hard seed coats ( Figueroa and Jaksic, 2004 ; Donoso Zegers, 2006 ; Gómez-González et al, 2017 ). Indeed, some evergreen tree species in the MTC area of Chile are known to have recalcitrant seeds ( Donoso Zegers, 2006 ).…”

“…Smoke- and heat-stimulated seed germination occurs in some herbaceous species in central Chile ( Figueroa et al, 2009 ; Gómez-González et al, 2011b ; Figueroa and Cavieres, 2012 ), but the majority of species are fire-intolerant, with an increasing number negatively affected as fires become more intense ( Gómez-González and Cavieres, 2009 ). Smoke- and heat-stimulated germination are present in less than a quarter and one-third of woody species in central Chile, respectively, but are mostly limited to colonizers ( Muñoz and Fuentes, 1989 ; Gómez-González et al, 2008 , 2017 ); however, close to half of all woody species are negatively affected and heat tolerance is far less evident than in herbaceous species (see also Table 1 for a comparison of the incidence of fire-response traits for central Chile and among MTC shrublands).…”