Smoke and heat can increase germination of common wildflowers and grasses—implications for conservation and restoration of critically endangered grassy ecosystems

Critically endangered grasslands and grassy woodlands were once widespread across south-eastern Australia. However, more than 200 years of European land use means less than 1% of their pre-European extent remains today. Conservation and restoration of these ecosystems involves reintroducing fire to periodically reduce competition and allow smaller species to establish. Furthermore, seeds of native species are sown – but often fail to establish as many forbs and grasses are hard-to-germinate. Therefore, data on how these species respond to fire-related germination cues, such as smoke and heat, can benefit our understanding of both how species respond to fire and identify treatments which can be used to increase germination. We conducted a germination trial to determine if smoke and heat cues increase percent germination and germination speed of 55 common grassy ecosystem species. Fire cues increased germination speed and/or percent germination of 44 of the 55 study species. These results have three implications for grassy ecosystem conservation and restoration: (i) fire may aid conservation by maximizing germination of native species; (ii) pre-treating seed with smoke and/or heat prior to sowing may increase germination when restoring these ecosystems via direct seeding; and (iii) smoke and heat can be used to increase germination when growing seedlings for plantings.