Australian Journal of Botany Australian Journal of Botany Society
Southern hemisphere botanical ecosystems

Australian Journal of Botany

Australian Journal of Botany

Australian Journal of Botany is an international journal for the publication of original research and reviews in plant science with relevance to Southern Hemisphere ecosystems including ecology and ecophysiology, conservation biology and biodiversity, forest biology and management, cell and molecular biology, palaeobotany, reproductive biology and genetics, mycology and pathology and structure and development. Read more about the journalMore

Editor-in-Chief: Dick Williams

Current Issue

Australian Journal of Botany

Volume 65 Number 2 2017

BT16170Subtropical native grasslands may not require fire, mowing or grazing to maintain native-plant diversity

Roderick J. Fensham, Donald W. Butler, Boris Laffineur, Harry J. MacDermott, John W. Morgan and Jennifer L. Silcock
pp. 95-102

The grasslands of temperate Australia seem to require disturbance to maintain species diversity. Grasslands in semiarid environments do not seem to have the same requirement. This short-term study suggests that subtropical grasslands on the Darling Downs do not have a requirement for disturbance to maintain species diversity. Drought in the subtropical environment may maintain grasslands in a sufficiently open structure to overcome the requirement for disturbance to maintain diversity of the intertussock flora.

Four small Australian desert succulents respond to drought by switching from CO2 uptake in the light to CO2 uptake in the dark. Uptake of CO2 in the dark enables plants to persist at low water-cost, thereby potentially aiding reproduction. The ability to switch between photosynthetic pathways is a trait that may be more common within Australia’s flora than considered previously.

BT16104Rainfall and grazing: not the only barriers to arid-zone conifer recruitment

Heidi C. Zimmer, Singarayer K. Florentine, Rita Enke and Martin Westbrooke
pp. 109-119

In arid Australia, the survival of a white cypress-pine seedling to maturity is rare. We found that fencing, particularly rabbit-proof fencing, resulted in increased numbers of white cypress-pine seedlings – but not at all sites. While protection from grazing is important for seedling survival, the potential for other factors to intervene means that rabbit-proof fencing does not guarantee the next generation of white cypress-pines.

BT16197DNA ploidy variation and distribution in the Lepidosperma costale complex (Cyperaceae): implications for conservation and restoration in a biodiversity hotspot

Mark J. Wallace, Lydia K. Guja, Marie A. Jouault, Kathy A. Fuller, Russell L. Barrett, Siegfried L. Krauss and Matthew D. Barrett
pp. 120-127

Genome multiplication (polyploidy) is an important phenomenon in plant evolution and has significant implications for conservation and ecological restoration. We studied genome multiplication in a group of rare sedges (the Lepidosperma costale species complex) in south-west Western Australia. Four ploidy levels were discovered, suggesting that polyploidy may be an important driver of diversification in these sedges.

BT16190Genetic structure of Gahnia radula (Cyperaceae), a key sedge for revegetation

Alex Arnold, Andrea Kodym, Nancy M. Endersby-Harshman, John Delpratt and Ary A. Hoffmann
pp. 128-139

Gahnia radula is an important species of sedge needed for vegetation restoration. To understand the extent and source of genetic variation in this species in southern Australia, variation within different populations of the species was investigated. Knowledge gained from the study indicates a prevalence of asexual reproduction and supports recommendations for areas suitable for sourcing material for revegetation.

BT16086High levels of population differentiation in two New Caledonian Scaevola species (Goodeniaceae) and its implications for conservation prioritisation and restoration

Adrien S. Wulff, Peter M. Hollingsworth, Marie Piquet, Antje Ahrends, Laurent L'Huillier and Bruno Fogliani
pp. 140-148

Population genetics is a key element for the conservation of endangered plant species. The comparison of two congeneric species of Scaevola in New Caledonia, one widespread and one narrow endemic, indicates high differentiation between populations, especially for the narrow endemic species on very small geographical scale. These results demonstrated the importance of conserving multiple populations of narrow endemic species even when they co-occur in close proximity.

Competition from neighbours can simultaneously favour increased dispersal and increased offspring provisioning (seed size), however, these functions trade-off with each other. We demonstrate a non-linear relationship between how fast seeds of wind dispersed Asteraceae species fall, and seed architecture (the size of the parachute like pappus versus the size of the ‘seed’). This non-linear relationship can be used to predict when plants allocate more to dispersal or provisioning when faced with intense competition.

Bark constitutes plant tissue that transports photosynthates and protects plants against pathogen attack, herbivore damage and high temperatures caused by Cerrado fires. Bark traits are directly related to fire protection in a fire-prone habitat and efficient photosynthate transport in a non-fire-prone habitat, with thicker rhytidome and wider sieve tubes respectively. Our study demonstrated that although bark anatomy is little studied, it offers rich diagnostic and adaptive information.

BT16254Phytotoxic effects of extract and essential oil of Eucalyptus saligna (Myrtaceae) leaf litter on grassland species

Eliane R. Silva, Diana C. Lazarotto, Joséli Schwambach, Gerhard E. Overbeck and Geraldo L. G. Soares
pp. 172-182

Eucalyptus plantations are replacing natural grasslands in South Brazil, and under these plantations few plants establish, but processes shaping this pattern have been scarcely investigated. We showed that Eucalyptus saligna releases chemical substances in leaf litter that inhibit germination and seedling growth of grassland species. Therefore, suppression of grassland vegetation under E. saligna plantations may be potentially related to effects of allelochemicals.

BT16140A phytosociological analysis of Butia yatay (Arecaceae) palm groves and gallery forests in Entre Rios, Argentina

Estela E. Rodriguez, Pablo G. Aceñolaza, Eliana Linares Perea and Antonio Galán de Mera
pp. 183-202

This work analysed the vegetation of gallery and savanna forest distributed in the lower Uruguay River basin. Plant associations of this vegetation type have been poorly studied. Plant communities are related to tropical forests of southern Brazil, but are present into a warmer climate zone because of the north–south corridor generated by the Uruguay River. Two new associations and a new alliance are described to add to the syntaxonomical scheme of Argentina, with the aim to improve the knowledge of the diversity of its plant communities.

Online Early

The peer-reviewed and edited version of record published online before inclusion in an issue

Published online 30 May 2017

BT16238Pollen development and orbicule and pollen grain morphology in species of Cephalanthus (Rubiaceae-Naucleeae) from the Americas

María Florencia Romero, Roberto Salas and Ana Maria Gonzalez

This study is the first embryological report on male structures in the genus Cephalanthus. It includes the analysis of anther development, both the study of the processes leading to the formation of pollen and the histology of the wall of the anther, describing how dehiscence occurs. The results contribute to future studies in other genera of the tribe Naucleeae in the Rubiaceae family.

Germination of fire-prone plant species can be complex. Understanding this key component of the regeneration niche can help elucidate mechanisms for persistence and inform conservation. Like many threatened species in fire-prone south-eastern Australia, Asterolasia buxifolia is restricted to riparian habitats. Germination ecology of this physiologically dormant family (Rutaceae) is not well understood. We found that seeds germinated only with smoke at winter temperatures. Darkness inhibited germination. These results help us understand why such species may be limited to riparian habitat.

Published online 30 May 2017

BT16147Gleditsia triacanthos (Fabaceae) in Argentina: a review of its invasion

Romina D. Fernandez, Sergio J. Ceballos, Agustina Malizia and Roxana Aragón

Gleditsia triacanthos is a woody exotic species that colonises different ecosystems in several countries around the world. In this work we review numerous studies about its invasion to show its importance as an invasive species in Argentina. Since the end of the 18th century, G. triacanthos has spread across different ecoregions in Argentina affecting flora, fauna and ecosystem processes. Our review highlights the need to develop monitoring and control strategies for this invasive species.

Published online 30 May 2017

BT16183Intraspecific diversity of terpenes of Eucalyptus camaldulensis (Myrtaceae) at a continental scale

Carlos Bustos-Segura, Shannon Dillon, Andras Keszei, William J. Foley and Carsten Külheim

Eucalyptus camaldulensis is the most widely distributed Eucalyptus species both globally and in its native range. In the present study, we explored the natural variation in foliar terpene composition across its natural distribution in Australia and how elevated CO2 can affect the accumulation of terpenes. We found four chemical varieties dominated by different monoterpenes across the natural range. In addition, plants growing under elevated CO2 accumulated a lower concentration of monoterpenes, suggesting that climate change can affect terpene accumulation in natural populations and plantations.

Physical dormancy prevents immediate germination of seed and allows species to maintain a persistent soil seed bank providing the resource for post-fire recovery of plant populations. Temperature is a key driver for dormancy release but hot summer temperatures can result in rupture of the seed coat in the inter-fire period. Gradual leakage of seed from the seed bank under a warming climate may compromise the risk-spreading ability afforded by hardseededness potentially reducing species capacity to recover from disturbance.

Published online 15 May 2017

BT16253Evidence of reward production and pollination by Centris in Encyclia (Orchidaceae: Laeliinae): the reproductive biology of Encyclia mapuerae

A. H. Krahl, D. R. P. Krahl, J. J. Valsko, A. C. Webber and E. R. Pansarin

In this paper we report on studies of the reproduction biology of an Amazonian orchid pollinated by Centridini bees that search for nectar on flowers. To our knowledge, this is the first report of reward production in Encyclia. This discovery provides new insights on the function of the cuniculus in Laeliinae, and sheds light on the evolution of floral rewards and pollination mechanisms within this diverse group of Neotropical orchids.

Published online 08 May 2017

BT16179Causes and consequences of variation in snow incidence on the high mountains of Tasmania, 1983–2013

Jamie B. Kirkpatrick, Manuel Nunez, Kerry L. Bridle, Jared Parry and Neil Gibson

The incidence of snow was largely constant between 1983 and 2013 at Mt Field and on other high mountains in Tasmania, but decreased on lower elevation alpine mountains, trends apparently caused by changes in atmospheric instability. At Mt Field, obligate snow patch species persisted during the same period and cushion plants and shrubs increased.

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