Exposure of dormant seed to cold smoke derived from burnt native vegetation had a positive influence on germination in one or more seed provenances in 45 out of 94 species of native Western Australian plants that are normally hard to germinate. When tested under controlled conditions some species showed earlier germination in smoke treatments than controls; in others smoke-treated seeds continued to germinate for several weeks after controls had achieved full germination. In the remainder, treated and control seeds germinated to similar time schedules. A group of 23 species which responded positively had previously been recorded as extremely difficult or impossible to germinate using conventional techniques. These included members of the genera Geleznowia (Rutaceae), Hibbertia (Dilleniaceae), Stirlingia (Proteaceae), Verticordia (Myrtaceae), Actinostrobus (Cupressaceae) and Pimelea (Thymelaeaceae). Both large- and small-seeded species were encountered amongst the positively responding taxa, which encompassed representatives of 15 families and 26 genera of dicotyledons, 5 families and 8 genera of monocotyledons and the gymnosperm Actinostrobus acuminatus. Sowing seeds on smoke-fumigated filter papers or watering with aqueous eluates of smoke elicited similar degrees of stimulation of germination, as did exposure to gaseous smoke in a readily germinating species Anigozanthos manglesii (Haemodoraceae) and the normally intractable species Lysinema ciliatum (Epacridaceae). Exposing recently burnt and unburnt natural bushland sites to smoke, smoked water or smoked dry sand elicited a significant germination response in 15 species. Over one third of the species sampled in the burnt site exhibited germination additional to that caused by the fire. Data are discussed in relation to previous germination studies on Australian and other taxa.

Seed germination of many Australian native plant species has consistently proven to be fractious. With the discovery of smoke-mediated germination, it is now possible to better understand the heterogeneity in germination patterns for a wide range of species both in situ and ex situ. In the present study, over 180 species were examined as to viability and smoke responsiveness of freshly collected seed. Soil storage and a number of commonly used seed pre-treatments were employed in combination with smoke to examine both longevity in artificially constructed seed banks, and the role of seed ageing in improved germination. Methods of smoke application for commercial use were also investigated. Viability decline over 1 year varied between 10% and 80%. Reductions of as little as 15% were found to compromise the ability of a number of species to successfully recruit in consecutive seasons. When fresh seed was used,almost 70% of species tested responded positively to smoke whether applied prior to or after sowing. Variation in success between the two methods confirmed earlier conclusions that substances contained in plant-derived smoke may be inhibitory at high concentrations for particularly sensitive species. Only 10% of species under investigation recorded optimum germination with seed ageing alone but when smoke was applied as a treatment after soil storage, 60% of species responded positively. Implications for horticulture, rehabilitation, seed bank research and habitat management are discussed.

Cool smoke treatments were applied to unmined Eucalyptus marginata (jarrah) forest soils, rehabilitated bauxite mine soils, and broadcast seed to determine if enhancement in germination could be effected with a view toward maximizng the establishment of species in bauxite mines in Western Australia. Forest sites showed a 48‐fold increase in total germinants from the soil seed bank when treated with aerosol smoke. Newly returned bauxite mine soils showed a greater than threefold increase in total germinants after the same treatment. There were also significant increases in the number of species germinating in response to the aerosol smoke treatment in both the forest and the mined soils. Similarly, application of smoked water to the soil seed bank in previously mined sites elicited a significant positive germination response, increasing total germinants and species numbers by 56 and 33%, respectively. Treatment of mixed seed lots with aerosol smoke before broadcast resulted in highly significant improvement in germination when compared to untreated seed. Both total number of germinants, and number of species emerging from mined sites were positively influenced (85% and 34% increases, respectively). Ten target species were used to determine the relative effectiveness of different methods of smoke treatment on the germination of broadcast seed. Nine of the species involved displayed a promotive effect with at least two of the treatments. Generally, however, aerosol smoking of seed before broadcast proved to be the more effective approach. As a result of these findings, all broadcast seed for use in Alcoa's bauxite mined areas in the southwest of Western Australia is now routinely smoke treated before application.

The influence of factors associated with fire on seed germination of Australian native species is generally well documented, but examples involving the use of smoke as a fire analogue for ecological research remain limited. The role of season of treatment in the efficacy of smoke as a promotive germination agent was investigated over two growing seasons using natural soil stored seedbanks in Banksia woodland near Perth, Western Australia. Smoke was applied to unburnt sites in the autumn, winter and spring of 1994. Germinant emergence and seedling survival of 37 species representing 18 families was monitored in both unburnt sites and in adjacent, recently burnt sites until the second spring after treatment (October 1995). Recruitment from seed was found to be profoundly affected by the season in which dormancy breaking treatment had been applied. The promotive effect extended beyond the mitial year of application. For the majority of the species investigated, application of smoke to unburnt sites in autumn promoted a significantly greater germination response than treatment in winter or spring. In only three cases (introduced annuals, the Fabaceae and Hibberiia amplexicaulis) did autumn smoke treatment not yield better germination than in summer-burnt counterparts. However, in almost half of the cases examined, proportions of seedlings surviving past their first summer after emergence in burnt areas were consistently greater than those in smoked or untreated sites. Most notably, no seedlings emerging during the spring ofthe first year of study survived into the following summer. Implications of the results with respect to future seed bank research and management of native vegetation are discussed.