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.
Australian Journal of Botany
Volume 65 Number 3 2017
BT16179Causes and consequences of variation in snow incidence on the high mountains of Tasmania, 1983–2013
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.
BT16253Evidence of reward production and pollination by Centris in Encyclia (Orchidaceae: Laeliinae): the reproductive biology of Encyclia mapuerae
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.
BT16238Pollen development and orbicule and pollen grain morphology in species of Cephalanthus (Rubiaceae-Naucleeae) from the Americas
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.
BT16244Are we underestimating the impact of rising summer temperatures on dormancy loss in hard-seeded species?
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.
BT16183Intraspecific diversity of terpenes of Eucalyptus camaldulensis (Myrtaceae) at a continental scale
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.
BT16216Demographic, dispersal, predation and genetic data reveal the potential vulnerability of an endangered rainforest shrub, Triunia robusta (Proteaceae)
We investigated the demographic, dispersal and predation dynamics of an endangered rainforest shrub, Triunia robusta (Proteaceae). A life cohort table was developed from field demographic data, the potential dispersal distance was assessed and the effects of predation on seed and seedling mortality were quantified. It was found that T. robusta has limited dispersal, high post-predation mortality rates and relatively low reproductive rates, suggesting that critically small and isolated populations may be highly vulnerable.
BT17025Germination ecology of the endangered species Asterolasia buxifolia (Rutaceae): smoke response depends on season and light
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.
Measuring xylem conduit length and distribution is important but tedious, and so it is often avoided. For decades, several measurement techniques have been debated, so we compared four classic methods and found none to be significantly different; however, we recommend the Christman method because it ensures ease of calculation. Accurate calculation of conduit length is crucial for many reasons, including comparison of global datasets on the potential plasticity of xylem characteristics, which is important information in a changing climate.
The peer-reviewed and edited version of record published online before inclusion in an issue
BT16261A comparison of xylem vessel metrics between tropical and temperate Rhododendron species across elevation ranges
Temperate species of Rhododendron are protected from freezing induced embolisms by narrow vessels and have low efficiency for water flow, which is maladaptive for tropical species. We discovered that tropical Rhododendron species marginally relax protection against freeze–thaw and increase water flow capability. The trade-off between safety and efficiency in plants is supported, but change is limited within this single genus.
BT16242Floral morphology of Eucalyptus leucoxylon (Myrtaceae) facilitates pollination by lorikeet (Aves: Psittacidae) tongues
Lorikeets feed on large numbers of Eucalyptus flowers and supposedly pollinate some species, yet floral traits that facilitate this type of pollination have never been examined. Flowers of some species release pollen before the filaments unfurl, potentially excluding insects and allowing lorikeets to lick pollen with their tongues, which is then carried in large numbers to other flowers. These morphological and developmental traits facilitate considerable pollinator specificity.
Forest fragmentation is a major threat to tropical biodiversity. We investigated how biotic and abiotic factors affect total abundance and the numbers of individuals at each life stage of Psychotria vellosiana Benth. Our results indicate that forest fragmentation has led to alterations in the structure and abundance of this species, as all of its life stages are adversely affected by liana and bamboo cover.
This unique long-term fire study in the Wheatbelt region of WA examined time to first flowering in 180 species and, in 60 of these, time to peak flowering over a 30-year period so as to inform land managers as to the appropriate fire intervals for kwongan shrublands and woodland understorey. Non-resprouting species with seed store in the canopy are most vulnerable to fire, take longer to first flower but are slightly quicker to reach peak flowering than resprouting species. Consequently, kwongan communities need a minimum fire interval of between 15 and 20 years and Allocasuarina woodlands of at least 25–30 years to reduce immaturity risk.
What happens to bark once it is shed from the trunk of eucalypt trees? Decomposition and flammability of bark (and leaves) of 10 common species were quantified, and considerable variation in decomposability and flammability was found both within and across species, as driven by different physical and chemical traits. Taking species-specific bark traits into consideration can lead to better estimates of carbon losses and fire risks, and could improve management decisions for Australian forests and plantations worldwide.
Davallia (Pachypleuria) angustata (Wall. ex Hook. & Grev.) is a common epiphytic fern that grows on tree trunks and palm trees in south-east Asia. Photosynthetic recovery experiments show that Davallia is a homiochlorophyllous resurrection plant. It is a sun plant (optimum irradiance is at ~45% of full sunlight). Its diurnal titratable acid cycle shows that it is not a CAM plant despite its succulent leaves.
BT16235Designing food and habitat trees for urban koalas: identifying short ecotypes of Corymbia intermedia
Many householders and councils prefer to plant short trees because tall trees may present a danger from falling limbs. We identified short populations of the normally-tall pink bloodwood tree, Corymbia intermedia, growing on exposed coastal headlands. We raised seedlings from these short trees and found that they were shorter in cultivation than seedlings from tall trees. These shorter eucalypt trees have potential for planting in gardens, streets and parklands as food and habitat for koalas and other urban fauna.
BT16232High outcrossing rates and short-distance pollination in a species restricted to granitic inselbergs
Encholirium horridum is a species of bromeliad – the same family of plants as the pineapple – that only occurs on some isolated granitic outcrops in Brazil. Its flowers are mainly pollinated by bats and hummingbirds. And although these animals can fly over a long distance, pollen movement among flowers was concentrated in the neighbourhood. This affects seed viability and outcrossing rates of this endangered plant.
Metal mine tailings have emerged as a global environmental threat and require urgent rehabilitation with sustainable native plant communities. Native Acacia species as keystone species in semiarid regions of Australia exhibited different root exudation capability and associated metal uptake. As a result, those Acacia species taking up low levels of metals may be selected for the initial rapid phytostabilisation of metal mine tailings.
BT17014Inhibitory action of allelochemicals from Artemisia nanschanica to control Pedicularis kansuensis, an annual weed of alpine grasslands
Allelochemicals can be used for biological weed management and can minimise environmental impacts related to herbicides. The aim of the present study was to identify allelochemicals of Artemisia nanschanica, a weed with strong allelopathic effects, that could potentially control Pedicularis kansuensis, a weed that causes rapid degradation of alpine pastures. Three allelochemicals were identified that can be used to biologically control P. kansuensis.
These articles have been peer reviewed and accepted for publication. They are still in production and have not been edited, so may differ from the final published form.
Aeluropus littoralis maintains adequate gas exchange, pigment composition, and phenolic contents under combined effects of salinity and phosphorus deficiency.
Relationship between nitrogen resorption and leaf size in the aroid vine Rhodospatha oblongata (Araceae)
Influence of auxin and phenolics accumulation on the patterns of cell differentiation in distinct gall morphotypes on Piptadenia gonoacantha (Fabaceae)
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Australian Journal of Botany 65 (3)Jamie B. Kirkpatrick, Manuel Nunez, Kerry L. Bridle, Jared Parry, Neil Gibson
A framework for testing the influence of Aboriginal burning on grassy ecosystems in lowland, mesic south–eastern AustraliaAustralian Journal of Botany 64 (8)Paul W. Foreman
Australian Journal of Botany 65 (3)Romina D. Fernandez, Sergio J. Ceballos, Agustina Malizia, Roxana Aragón
Germination ecology of the endangered species Asterolasia buxifolia (Rutaceae): smoke response depends on season and lightAustralian Journal of Botany 65 (3)Justin C. Collette, Mark K. J. Ooi
Australian Journal of Botany 65 (3)Carlos Bustos-Segura, Shannon Dillon, Andras Keszei, William J. Foley, Carsten Külheim
Subtropical native grasslands may not require fire, mowing or grazing to maintain native-plant diversityAustralian Journal of Botany 65 (2)Roderick J. Fensham, Donald W. Butler, Boris Laffineur, Harry J. MacDermott, John W. Morgan, Jennifer L. Silcock
Are we underestimating the impact of rising summer temperatures on dormancy loss in hard-seeded species?Australian Journal of Botany 65 (3)Anne Cochrane
Australian Journal of Botany 65 (3)Virginia G. Williamson, John A. Milburn
Evidence of reward production and pollination by Centris in Encyclia (Orchidaceae: Laeliinae): the reproductive biology of Encyclia mapueraeAustralian Journal of Botany 65 (3)A. H. Krahl, D. R. P. Krahl, J. J. Valsko, A. C. Webber, E. R. Pansarin
Pollen development and orbicule and pollen grain morphology in species of Cephalanthus (Rubiaceae-Naucleeae) from the AmericasAustralian Journal of Botany 65 (3)María Florencia Romero, Roberto Salas, Ana Maria Gonzalez
Australian Journal of Botany 65 (2)Klaus Winter, Joseph A. M. Holtum
Australian Journal of Botany 65 (2)Heidi C. Zimmer, Singarayer K. Florentine, Rita Enke, Martin Westbrooke
DNA ploidy variation and distribution in the Lepidosperma costale complex (Cyperaceae): implications for conservation and restoration in a biodiversity hotspotAustralian Journal of Botany 65 (2)Mark J. Wallace, Lydia K. Guja, Marie A. Jouault, Kathy A. Fuller, Russell L. Barrett, Siegfried L. Krauss, Matthew D. Barrett
Australian Journal of Botany 64 (8)Mike Macphail, Andrew H. Thornhill
Demographic, dispersal, predation and genetic data reveal the potential vulnerability of an endangered rainforest shrub, Triunia robusta (Proteaceae)Australian Journal of Botany 65 (3)Yoko Shimizu-Kimura, Scott Burnett, Alison Shapcott
Australian Journal of Botany 65 (1)Olusegun O. Osunkoya, Nurul Amal Muntassir
Australian Journal of Botany 65 (2)Alex Arnold, Andrea Kodym, Nancy M. Endersby-Harshman, John Delpratt, Ary A. Hoffmann
Allometry in the terminal velocity – dispersal architecture relationship explains variation in dispersal and offspring provisioning strategies in wind dispersed Asteraceae speciesAustralian Journal of Botany 65 (2)Samiya Tabassum, Stephen P. Bonser
Australian Journal of Botany 65 (1)Bilan Huang, Li Xu, Kelie Li, Yunlu Fu, Zhiying Li
A genetic, demographic and habitat evaluation of an endangered ephemeral species Xerothamnella herbacea from Australia’s Brigalow beltAustralian Journal of Botany 65 (1)Alison Shapcott, Robert W. Lamont, Gabriel Conroy, Heather E. James, Yoko Shimizu-Kimura