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Australian Journal of Botany



Recent research papers from the Australian Journal of Botany



 



Effects of selective thinning and residue removal on ground layer structure and diversity in a mixed pine–oak stand of the Qinling Mountains, China

2017-09-21

Lin Hou, Shan Sun, Liyan Liang, Ge Liang, Luxi Jiang

Understorey is a key component of a forest ecosystem. Forest thinning may change the structure, diversity and cover of the understorey by reducing tree density and increasing gaps in the forest canopy. To achieve the highest richness, evenness and cover, a combination of selective thinning intensity and residue removal rate were suggested by applying a central composite design.





The importance of travelling stock reserves for maintaining high-quality threatened temperate woodlands

2017-09-21

Thea O'Loughlin, Luke S. O'Loughlin, Damian R. Michael, Jeffrey T. Wood, Helen P. Waudby, Phillip Falcke, David B. Lindenmayer

Travelling stock reserves (TSRs) are critically important for the conservation of temperate woodland communities that have otherwise been extensively cleared and degraded for agriculture. We compared the vegetation attributes of TSRs with remnants managed for agricultural production and found the former supported higher native plant species richness, more native ground cover and fewer exotic plants. Our results indicate that land tenure status of remnant woodlands generally influenced several vegetation attributes that are also important for native biodiversity.





Pollinarium size as a hybridisation barrier between sympatric inter-compatible orchids

2017-09-19

B. C. Vieira, L. M. Pansarin, M. E. P. Martucci, L. Gobbo-Neto, E. R. Pansarin

This work reports on the occurrence of natural hybridisation between three sympatric orchid species. The reproduction of the species was recorded based on morpho-anatomical, histochemical analyses and intra- and interspecific crosses. The relationship between co-occurring species was verified by floral morphometry and principal component analysis, and sequence divergence analyses. All data collected suggest that no gene flow is currently occurring, and that hybridisation has been avoided due to the incompatible pollinarium size between the sympatric species, which acts as a pre-mating barrier in the studied population.





Seed dormancy and germination of three grassy woodland forbs required for diverse restoration

2017-09-14

Gabrielle S. Vening, Lydia K. Guja, Peter G. Spooner, Jodi N. Price

Restoration is vital for the re-establishment of degraded communities, but success is often hindered by issues related to seed biology. We examined dormancy-alleviation and germination-promotion techniques for three common grassy woodland forbs required for diverse restoration. Scarification of the seed produced the highest germination for Dianella longifolia and Stackhousia monogyna, whereas germination of Dianella revoluta requires further examination. This information can advance methods to propagate these species from seed and contribute to greater understorey diversity in grassy woodland restoration.





Regarding the structure and possible function of the columella in seed cones of Callitroideae (Cupressaceae): a morpho-anatomical approach

2017-09-05

Veit Martin Dörken, Armin Jagel - Volume 65(5)

Several callitroid Cupressaceae have a column-like structure – termed ‘columella’ – that are developed distally in the seed cones, which exclusively represents the prolonged tip of the cone axis. Thus, the distal three-part structure of Fitzroya represents a sterile whorl of cone scales that should not be termed columella. It is suggested that columellae that exceed the ovules, play a role in the pollination process, whereas prolonged, resinous columellae play a role in the chemical defence against pathogens.





Nickel effect on root-meristem cell division in Plantago lanceolata (Plantaginaceae) seedlings

2017-08-24

Dolja Pavlova - Volume 65(5)

Plantago lanceolata is a variable species growing on different soils but is not abundant on serpentines. Nickel effect on root-cell division is the reason for the low percentage of divided cells, high percentage of abnormalities, and variation of karyotype morphology. Unsuccessful distribution of the species on serpentine soils is related to its poor adaptation to stress conditions provided by the elevated metal concentrations in the soils.





Adaptive strategy of tree communities on an environmental harshness hinterland inselberg in Minas Gerais, Brazil

2017-08-21

Felipe de Carvalho Araujo, Carolina Njaime Mendes, Gabriela Gomes Pires, Gisele Cristina de Oliveira Menino, Marco Aurelio Leite Fontes, Rubens Manoel Dos Santos - Volume 65(5)

Our research tested the hypotheses that environmental harshness enhances sprouting, a trait displayed by trees as an adaptive strategy to habitat persistence. Over the 5 years of the study, sprouting proved to be a strategy of persistence. Multi-stemmed trees have different dynamics compared to single-stemmed trees. Factors such as soil depth, may be the cause of sprouting in trees.





Aeluropus littoralis maintains adequate gas exchange, pigment composition and phenolic contents under combined effects of salinity and phosphorus deficiency

2017-08-17

Ons Talbi Zribi, Kamel Hessini, Najla Trabelsi, Fethia Zribi, Abdelwahed Hamdi, Riadh Ksouri, Chedly Abdelly - Volume 65(5)

The ability of Aeluropus littoralis to cope with both phosphorus (P) deficiency and high salt stresses is a result of several mechanisms mainly involved in the conservation of the integrity of the photosynthetic apparatus. Secondary metabolites – mainly phenolic compounds and carotenoids – play an important role in the protection of A. littoralis plants against oxidative damage under combined high salinity and P deficiency stresses.





Relationship between nitrogen resorption and leaf size in the aroid vine Rhodospatha oblongata (Araceae)

2017-08-10

André Mantovani, Dulce Mantuano, Eduardo Arcoverde de Mattos - Volume 65(5)

Although leaves of Rhodospatha oblongata increased 35 times in area and 50% in vein density, the N concentration was always around 2–3% in green leaves and 1–2% in senescent leaves. Consequently, increase in vein density or in the amount of leaf N content were not the main constraining factors to leaf nitrogen resorption.





Influence of auxin and phenolic accumulation on the patterns of cell differentiation in distinct gall morphotypes on Piptadenia gonoacantha (Fabaceae)

2017-08-10

Cibele Souza Bedetti, Gracielle Pereira Bragança, Rosy Mary dos Santos Isaias - Volume 65(5)

The accumulation of IAA–phenolics was compartmentalised on the basis of gall morphotypes on Piptadenia gonoacantha. The sites of accumulation coincided with the most hypertrophied regions, i.e., the cells of superior and lateral inferior cortices in the lenticular galls, and throughout the outer cortex in the globoid galls, which influenced on the determination of the lenticular and globoid shapes.





Going nowhere fast: a review of seed dispersal in eucalypts

2017-08-08

Trevor H. Booth - Volume 65(5)

This paper considers how far natural stands of eucalypt species are likely to be able to disperse in the period to 2085. Although rare long-distance events cannot be ruled out, the most likely dispersal distances are about 70–140 m. However, limitations such as inadequate remnant stands and extensive agricultural developments may reduce actual migration rates below even this modest potential.





Reproductive size thresholds and seedling survival in Acacia harpophylla (Mimosaceae)

2017-07-31

John M. Dwyer - Volume 65(5)

The capacity of Acacia harpophylla (brigalow) to resprout on cleared land is well documented, but its ability to recruit new individuals sexually is poorly understood because such reproduction events are rare. This study, undertaken following widespread flowering in late 2007, recorded very high initial densities of germinated seedlings (46 000 seedlings ha–1 on average), but less than 1% were estimated to survive the first year. Given the dramatic over-clearing of brigalow, such ecological knowledge is crucial for managing remaining populations.





Thermogenesis and developmental progression of Macrozamia macleayi pollen cones

2017-07-25

R. B. Roemer, D. Booth, L. I. Terry, G. H. Walter - Volume 65(5)

The thermal activity of Macrozamia macleayi Miq. (family Zamiaceae) pollen cones changes with developmental stage in a manner similar to Cycas micronesica K.D. Hill (family Cycadaceae) pollen cones, suggesting a conserved physiological response across cycad families. The Macrozamia macleayi cones use carbohydrates, but not lipids, to fuel their large dehiscence stage thermogenic events, during which evaporation rates increase considerably.





A comparison of xylem vessel metrics between tropical and temperate Rhododendron species across elevation ranges

2017-07-20

Tatpong Tulyananda, Erik T. Nilsen - Volume 65(4)

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.





Floral morphology of Eucalyptus leucoxylon (Myrtaceae) facilitates pollination by lorikeet (Aves: Psittacidae) tongues

2017-07-17

Joseph P. Zilko, Susan E. Hoebee, Trevor J. Edwards - Volume 65(4)

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.





Liana and bamboo cover threaten shrub populations in Atlantic forest fragments

2017-07-12

Magda Silva Carneiro, Caroline Cambraia Furtado Campos, Flavio Nunes Ramos - Volume 65(4)

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.





Long-term studies of post-fire reproduction in an Australian shrubland and woodland

2017-07-05

J. M. Harvey, A. J. M. Hopkins, M. A. Langley, C. R. Gosper, M. R. Williams, C. J. Yates - Volume 65(4)

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.





Bark traits, decomposition and flammability of Australian forest trees

2017-07-04

Saskia Grootemaat, Ian J. Wright, Peter M. van Bodegom, Johannes H. C. Cornelissen, Veronica Shaw - Volume 65(4)

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.