Smoke stimulates germination in two divergent Gondwanan species (Hibbertiapancheri and Scaevola montana) endemic to the biodiversity hotspot of New Caledonia

Abstract

Due to shared geological history and proximity, the flora of New Caledonia is closely linked to other Gondwanan land fragments such as Australia and New Zealand. Many predominant Australian groups are well represented within the New Caledonian flora, including the genera Hibbertia (23 species) and Scaevola (10 species). Previous studies have found that these two genera in particular have a marked positive germination response to smoke products, although all previous studies have centred on Australian species from fire-prone environments. In this present study, we test the hypothesis that two New Caledonian species of Hibbertia and Scaevola are smoke responsive even though the climate and ecological drivers in New Caledonia are in many respects fundamentally different from those of most of Australia. Preliminary results showed that germination of Hibbertia pancheri was significantly accelerated in response to smoke water while germination in Scaevola montana was also significantly enhanced. To the best of our knowledge, this is the first time that these trends have been illustrated for any New Caledonian species and these results will enhance restoration efforts of ultramafic scrublands impacted by mining activities in New Caledonia.

Alleviation of morphophysiological dormancy in seeds of the Australian arid-zone endemic shrub, Hibbertia glaberrima F. Muell. (Dilleniaceae)

“…One such example of seed responsiveness to environmental cues was observed in this study, whereby, once dormancy had been alleviated to its full extent through stratification, seeds of H. glaberrima showed an increase in germination when exposed to KAR 1 . This response is consistent with many previous reports of smoke-stimulated germination in seeds of other Hibbertia species (Dixon et al ., 1995; Roche et al ., 1997; Hidayati et al ., 2012; Wulff et al ., 2012). However, there were differences in the KAR 1 response when comparing the 8- to 16-week stratification treatments.…”

“…Hibbertia is a large genus ( ca 225 species) of the family Dilleniaceae that is widely distributed throughout Australia, with a smaller number of species also occurring in Madagascar, New Guinea, New Caledonia and Fiji (Wheeler et al ., 1992; Horn, 2007). Previous studies investigating seed dormancy and germination characteristics in Hibbertia species from the south-west Western Australia (Mediterranean climate) and New Caledonia (tropical climate) have noted that their seeds are often deeply dormant, are slow to germinate, and possess MD or MPD (Schatral, 1996; Schatral et al ., 1997; Allan et al ., 2004; Hidayati et al ., 2012; Wulff et al ., 2012). For example, seeds of H. pancheri from New Caledonia only germinated after incubation for 50 days at 30°C, irrespective of whether seeds were exposed to a germination stimulant (Wulff et al ., 2012), while seeds of H. commutata from Western Australia did not germinate for at least 18 weeks, even under favourable temperatures (Hidayati et al ., 2012).…”

“…Previous studies investigating seed dormancy and germination characteristics in Hibbertia species from the south-west Western Australia (Mediterranean climate) and New Caledonia (tropical climate) have noted that their seeds are often deeply dormant, are slow to germinate, and possess MD or MPD (Schatral, 1996; Schatral et al ., 1997; Allan et al ., 2004; Hidayati et al ., 2012; Wulff et al ., 2012). For example, seeds of H. pancheri from New Caledonia only germinated after incubation for 50 days at 30°C, irrespective of whether seeds were exposed to a germination stimulant (Wulff et al ., 2012), while seeds of H. commutata from Western Australia did not germinate for at least 18 weeks, even under favourable temperatures (Hidayati et al ., 2012). In the Mediterranean-type climate of south-west Western Australia, seeds of H. commutata , H. huegelii , H. hypericoides and H. racemosa are naturally exposed to a hot, dry summer period, followed by a cooler and wetter autumn and winter (Hidayati et al ., 2012).…”

“…H. amplexicaulis , H. commutata , H. huegelii , H. hypericoides , H. lasiopus , H. quadricolor and H. racemosa ) and New Caledonian (e.g. H. pancheri ) Hibbertia species increases in response to the application of aerosol smoke or its derivative compounds such as smoke-water or karrikinolide (KAR 1 ) (Dixon et al ., 1995; Roche et al ., 1997; Hidayati et al ., 2012; Wulff et al ., 2012).…”

Implications of seed traits for restoration of ultramafic plant taxa from the Goro plateau in the subtropical hotspot of New Caledonia

“…In our study, each species' types of dormancy and tolerance for seed desiccation were assessed based on several published findings (e.g. L'Huillier et al 2010; Zongo 2010; Wulff et al 2012; Baskin & Baskin 2014). We also used unpublished data from our research at IAC that appear in several reports (Tiavouane et al 2014, IAC, NC, personal communication; Birnbaum et al 2016).…”