Fires play an important role in many plant communities j2,5 8,13) After fires, propagutes of many
plant species that have remained dormant in the
soil seed bank germinate. Many factors, both physical and organic, may be responsible for this
improved germination. Dry heat may fracture the
seed coat of hard-seeded species./l°'l~ Such heat
may also have a direct influence on breaking
embryo dormancy. (3'14'17) High-temperature desiccation of the seed coat could break coat-imposed
dormancy, (41 while ethylene and ammonia present
in smoke may break embryo dormancy. (17/
Recently, it has been shown that plant-derived
smoke extracts or smoke stimulate the germination
ofmany plant species,/7/both fire-dependent, (5'6~and
non-fire-dependent. (9'16/ Active extracts have been
subjected to many chromatographic purification
steps, but as yet the active principal(s) remains