Does plant-derived smoke affect seed germination in dominant woody species of the Mediterranean matorral of central Chile?

摘要

Studies performed in the fire-prone Mediterranean-type climate shrublands of Australia, California, and South Africa have shown that plant-derived smoke enhances seed germination in many species. Unlike other areas with similar climate, central Chile stands out for the absence of natural fires, suggesting that smoke may not be expected to promote germination. However, anthropogenic fires have been frequent for several millennia, and the role of fire on shaping fire functional traits is not clear at this point. The aim of this study was to evaluate the effects of plant-derived smoke on seed germination of some predominant native woody species from the Mediterranean matorral of central Chile. We exposed seeds of 18 woody species to plant-derived smoke for 30 min and assessed their germination. Five species (Colletia hystrix, Colliguaja odorifera, Schinus polygamus, Solanum ligustrinum, Trevoa trinervis) failed to germinate under either the experimental and control conditions. Smoke significantly stimulated germination in three species (Acacia caven, Baccharis vernalis, Trevoa quinquenervia), while decreasing it in eight (Cryptocarya alba, Eccremocarpus scaber, Haplopappus schumannii, Kageneckia angustifolia, K. oblonga, Lithraea caustica, Maytenus boaria, Quillaja saponaria). Species showing smoke-inhibited germination tend to be major dominants in the Chilean matorral vegetation. The three smoke-stimulated species are known colonizers. This suggests that current human-caused fires could drastically change the structure of Chilean matorral. Although our results suggest fire have not played a major role in shaping adaptations for seed germination of woody species in the Chilean matorral, more investigation about ephemeral species is needed. This study provides the first results about smoke-related germination in the Mediterranean-type zone of central Chile, generating the opportunity to investigate the evolutionary context and distribution of smoke-stimulated germination in all the Mediterranean-type ecosystems.