An investigation of the soil seedbank and seed germination of perennial species in Belah (Casuarina pauper)woodlands in north-west Victoria
- Authors: Callister, Kate , Florentine, Singarayer , Westbrooke, Martin
- Date: 2018
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 66, no. 3 (2018), p. 202-212
- Full Text: false
- Reviewed:
- Description: Semiarid and arid woodlands across much of southern Australia have been subject to prolonged high total grazing pressure leading to loss of species diversity and a lack of recruitment of long-lived perennial species. Regeneration of perennial species requires grazing pressure to be maintained at low levels, but gaps remain in our ecological understanding of regeneration potential. The present study investigated the abundance of germinable seed in the soil seedbank in high quality remnants of Casuarina pauper F.Muell. ex L.A.S.Johnson (Belah) woodlands in north-west Victoria. Seed viability and response to six seed pretreatments including dry heat, wet heat, smoky water, soaking in distilled water, cold stratification and sand scarification were also tested to determine whether seed factors may be limiting regeneration. Results suggest that seed viability was not a limiting regeneration factor for nine out of the 10 perennial species tested with the exception of Alectryon oleifolius S.T. Reynolds. Only small amounts of seed from perennial species, largely Chenopodiaceae species and C. pauper, were found in the soil seedbanks of intact sites, suggesting component perennial species do not maintain long-term soil seedbanks. Results suggest that natural recovery of perennial species diversity in depauperate sites will depend on seed dispersal.
Arid land invasive weed Salvia verbenaca L. (wild sage) : Investigation into seedling emergence, soil seedbank, allelopathic effects, and germination
- Authors: Fisher, R. , Florentine, Singarayer , Westbrooke, Martin
- Date: 2016
- Type: Text , Conference paper
- Relation: Twentieth Australian Weeds Conference
- Full Text: false
- Reviewed:
- Description: y Salvia verbenaca L., wild sage (Lamiaceae) is native to western and southern Europe. In Australia S. verbenaca is considered an environmental weed with high invasiveness often growing on disturbed sites: tracks, roadsides and around earth tanks. Little is known about the ecology of this invasive species in Australia. Therefore, our objectives in this study were to determine: (i) seedling emergence in relation to sowing depth, (ii) density ofsoilseed bank, (iii) allelopathic effects, (iv) favourable conditions for seed germination of three month old and nine years old seeds, and (v) seed longevity. Of four burial depths, only surface sown seeds germinated and survived. From the soil seedbank, S. verbenaca density was 343 ± 198 m−2. For the allelopathic effects of S. verbenaca, neither the extract nor the leachate inhibited germination of L. sativa; however, the growth of the radicle of seedlings was shown to decrease. Germination was highest at 20°C under 12 h light/12 h dark. Burial of seeds in the field prior to germination reduced viability over time. Germination of three month old seed wassignificantly less than nine year old seed. In conclusion, it is clear that S. verbenaca functions as a casual weed in arid and semi-arid environments of Australia. Understanding the plants’ ecological characteristics in this study will help us take appropriate control measures for this species.
Influence of selected environmental factors on seed germination and seedling survival of the arid zone invasive species tobacco bush (Nicotiana glauca R. Graham)
- Authors: Florentine, Singarayer , Weller, Sandra , Graz, Patrick , Westbrooke, Martin , Florentine, Arunthathy , Javaid, Muhammad , Fernando, Nimesha , Chauhan, Bhagirath , Dowling, Kim
- Date: 2016
- Type: Text , Journal article
- Relation: Rangeland Journal Vol. 38, no. 4 (2016), p. 417-425
- Full Text: false
- Reviewed:
- Description: Tobacco bush (Nicotiana glauca R. Graham) is an aggressive invading species, which is active after disturbances such as high rainfall events and flooding. Past studies have focussed on population dynamics and allelopathic effects associated with the species, but little is known about its seed ecology. To address this dearth of information, this study aimed to investigate: (i) the effect of various stress factors (temperature, light, osmotic potential, salt stress, heat-shock, a combination of heat-shock and smoke, pH buffer, and burial depth of seed) on seed germination and seedling emergence, and (ii) factors affecting the fate of seedlings. The results show that N. glauca was able to germinate over a broad range of temperatures with highest seed germination occurring at 30/20°C with 12h of light and 12h of dark conditions. Seed germination was greatest (89%) when seeds were placed on the soil surface and emergence decreased considerably as planting depth increased from 0.5 to 1.5cm. Water stress greatly reduced seed germination (58% germination at osmotic potentials below -0.2 MPa) and germination was completely inhibited at water potentials of -0.4 to -0.6 MPa. Although increasing salinity reduced the seed germination of this invasive species, N. glauca seed was able to germinate in both alkaline (81% at pH 10) and acidic (80% at pH 4) conditions. The trial on the effect of seed age and field seed burial on seed germination showed a slight decline in seed germination after 120 days of burial compared with non-buried seeds. Further, the combined effect of heat-shock and smoke effectively inhibited the germination of N. glauca seeds; however, our study shows that seedlings of N. glauca can withstand heat-shock of up to 130°C. Studies such as this will assist in the development of control strategies to prevent the spread of this invasive species into arid landscapes. © 2016 Australian Rangeland Society.