Australian Journal of Botany

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.