Broad-scale patterns in smoke-responsive germination from the south-eastern Australian flora

Questions: Fire is a crucial component of many ecosystems. Plants whose seeds germinate in response to smoke may benefit from resource availability in the post-fire environment. Smoke can influence germination timing and success, as well as seedling vigour, resulting in burgeoning research interest in smoke-responsive germination. Research in this field has largely focused on four key 'Mediterranean-type' fire-prone ecosystems: the Mediterranean Basin, South African fynbos, Californian chaparral and Western Australia. There are far fewer studies from south-eastern Australia, a fire-prone but not "Mediterranean-type" region. How does smoke-responsive germination in this region vary according to ecological, phylogenetic, and methodological variables? Location: South-eastern Australia. Methods: We investigated patterns of smoke-promoted germination in south-eastern Australian plants across habitat types, growth forms, fire response strategies, phylogeny, taxonomic levels and smoke application methods. We compiled and interrogated data comprising 303 entries on germination responses to smoke in 233 south-eastern Australian plant species, from 33 different sources. Results: Smoke-responsive germination occurs at a lower rate (~41% of tested species) in south-eastern Australian flora than it does in fynbos and Western Australian floras, and there is clear patterning within these data. Obligate-seeding species were more likely to respond, Leguminosae and Rubiaceae were less likely to respond (although we question the generality of these results), while Poaceae were more likely to respond to smoke. Finally, studies using aerosol smoke and studies conducted in situ were most likely to find smoke-promoted germination. Conclusions: Obligate seeders and Poaceae may be selected for in habitats with higher fire frequencies, consistent with literature suggesting that short inter-fire intervals favour grasslands over forests. These findings may be particular to south-eastern Australia, or more widely applicable; more broad-scale comparative research will reveal the answer. By synthesizing the south-eastern Australian smoke germination literature we broaden our understanding beyond the better-studied Mediterranean-type floras.