ORCID Profile
0000-0002-7730-9685
Current Organisation
Murdoch University
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Publisher: Wiley
Date: 23-12-2004
Publisher: Wiley
Date: 19-01-2005
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/BT13150
Abstract: Serotiny is a widespread trait in angiosperms in the southern hemisphere however, it is less common in conifers and has been little examined in the only two genera of southern conifers (Callitris and Widdringtonia) that have serotinous cones. There is variation across the family in the size of cones, the amount of seed contained and the time over which the cones stay closed on the plant. Cones from most of the species were collected in the field and various morphometric measurements made including cone wet and dry weight, the number of seeds contained and their likely viability. Cones from a selection of species with different cone sizes were heated to increasing temperatures, to investigate the ability of cones to protect the contained seeds from heat. In comparison to the flowering plants, serotiny has developed comparatively recently in southern conifers (in the last 10–20 million years). In Widdringtonia, serotiny is relatively weak, whereas in Callitris, it varies from strong to non-existent. Cone size and fertile-seed production across the two genera varies and the number of fertile seeds produced is positively related to the size of the cone. In some species, there are sterile seed-like bodies. These may have developed to confuse seed predators, so fertile seeds have a better chance of survival. Larger (heavier) cones are more effective in protecting the contained seeds from the heat of fires than are smaller ones. There is no simple relationship between the cone size and type of environment occupied by the species. In regions where fire is unlikely, predictable but mild or completely unpredictable, the species tend to be non-serotinous. In temperate regions where hot fires are likely to have been a selective agent, the species tend to be more strongly serotinous, although fire is not essential to open the cones. The community and environment in which a species has evolved is likely to have influenced the development of the degree of serotiny for each species and this may still be a variable property among populations of some species, depending on the fire regime of the area in which they grow.
Publisher: Wiley
Date: 06-1979
Publisher: Oxford University Press (OUP)
Date: 10-05-2018
Publisher: Elsevier BV
Date: 2006
Publisher: Wiley
Date: 10-2018
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/BT19073
Abstract: Plants from arid environments have some of the most erse morphological and anatomical modifications of any terrestrial plants. Most perennials are classified as xerophytes, and have structures that limit water loss during dry weather, provide structural support to help prevent cell collapse during dry periods or store water in photosynthetic tissues. Some of these traits are also found in sclerophyllous plants and traits that may have developed due to evolution of taxa on nutrient poor soils may also benefit the plants under arid conditions. We examined the morpho-anatomical features of photosynthetic organs of three tree and four shrub species with reduced leaves or photosynthetic stems that occur in arid or semiarid sites in Australia to see if there were patterns of tissue formation particularly associated with xeromorphy. In addition, we reviewed information on succulent and resurrection species. In the tree species (Callitris spp.) with decurrent leaves clothing the stems, the close association between the water transport system and stomata, along with anisotropic physiology would allow the species to fix carbon under increasingly dry conditions in contrast to more broad-leaved species. The shrub species (Tetratheca species and Glischrocaryon flavescens) with photosynthetic stems had extensive sclerenchyma and very dense chlorenchyma. The lack of major anatomical differences between leafless species of Tetratheca from arid areas compared with more mesic sites indicates that quite extreme morphological modifications may not exclude species from growing successfully in competition with species from less arid areas. The sclerophyll flora now characteristic of Australian vegetation from seasonally arid climates may have evolved during mesic times in the past but with relatively minor modifications was able to adjust to the gradually drying climate of much of Australia up to the present time.
Publisher: Wiley
Date: 16-09-2016
Publisher: CSIRO Publishing
Date: 1998
DOI: 10.1071/BT97038
Abstract: In three closely related genera of the Proteaceae, namely, Lomatia R.Br., Stenocarpus R.Br. and Strangea Meisn. the pollen presenter and stigma at anthesis are covered by specialised cells. The cells are spiral-walled, contain polyphenolic material and are produced from the stigma, and in Lomatia from the pollen presenter. The spiral wall-thickenings are formed on the inside of the primary wall late in the development of the cells when they are budded off from the stigma or presenter surface. Pollen from the anthers is placed onto these cells from where it is taken to other flowers for cross-pollination. The spiral-walled cells prevent contact between self-pollen and the stigma and provide a method whereby cross-pollen can only reach the stigma if self-pollen has been removed. The form of the cells and the mechanism for preventing autogamy is not found in any other plant group.
Publisher: Oxford University Press (OUP)
Date: 12-2005
Publisher: Wiley
Date: 30-09-2019
Publisher: Springer Science and Business Media LLC
Date: 04-09-2020
Publisher: Elsevier BV
Date: 03-1999
Publisher: Wiley
Date: 02-1995
DOI: 10.2307/3236263
Publisher: Elsevier BV
Date: 03-2013
Publisher: Springer Science and Business Media LLC
Date: 25-06-2010
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/BT09040
Abstract: Understanding the causes of rarity and ways of managing populations of rare species is essential for their successful conservation. The present study applies the conceptual model of a hierarchy of causes to Lasiopetalum pterocarpum E.M.Benn. & K.Shep. (a critically endangered species) to understand better its reproductive and ecological attributes, possible reasons for its rarity and to determine whether this model assists in developing management strategies. L. pterocarpum subpopulations from Serpentine National Park were censused to record abundance, plant health, phenology, flower and fruit production and the presence of any seed bank. These characteristics were matched to criteria in the hierarchies of cause model. There was no evidence of recent seedling recruitment at any subpopulation. Hand-pollination produced a flower-to-fruit conversion proportion similar to that found in the field and self- and cross-pollinations produced virtually the same fruit set. Seed store in soil from beneath the native subpopulations and at a translocation site showed seed was patchily distributed and infrequent. L. pterocarpum is an obligate seeder, killed by fire and dependent on disturbance to break seed dormancy. However, smoke has no effect on germination. Seed production does not constrain population growth, because seedling regeneration after fire in 1999 was prolific at sites where plants had been growing. In the hierarchies of cause framework, the main causes of rarity for this species are taxon ecology, life-history strategy and stochasticity. Thus, concentrating active management on factors related to life history such as mosaic patch burning, fencing after fire to exclude vertebrate grazers, weed control and establishment of translocated populations will aid the preservation of this species in the wild.
Publisher: Springer Science and Business Media LLC
Date: 2002
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/BT09043
Abstract: Calytrix breviseta Lindl. subsp. breviseta is a critically endangered, obligate-seeder shrub within fire-prone kwongan of south-west Western Australia. Little is known about the species’ reproductive biology and how threatening processes, particularly altered fire regimes and exotic species invasion, will impact the long-term viability of the species. This study aims to elucidate the species’ reproductive biology and patterns of seedling recruitment during succession after fire. The effects of changes to the fire return interval and exotic species invasion on the long-term viability of the species is also described. The species exhibits abundant recruitment following fire and the application of a smoke treatment significantly improves germination, similar to many other Western Australian shrubs. However, significant inter-fire recruitment was observed up to 10 years following fire, leading to the presence of multi-aged subpopulations, although seedling recruitment was negligible years after fire. The juvenile period is short at 3–4 years to first flowering. Population viability analysis (PVA) predicted that the optimal fire return interval to maintain C. breviseta subsp. breviseta was dependent on the carrying capacity (K) of the community and the number of in iduals present. Carrying capacity will be related to site quality and competition from invasive species. PVA showed that if K remains high, then the optimal fire return interval is ~15–20 years, but under lower carrying capacity, (i.e. weed competition) fires decrease the likelihood of population survival.
Publisher: Elsevier BV
Date: 09-1996
Publisher: Oxford University Press (OUP)
Date: 07-1994
Publisher: Wiley
Date: 04-2009
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/BT19122
Abstract: Plant species conservation relies on their reproductive success and likelihood of population persistence. Knowledge of plant mating systems, particularly the relationship between plants and their pollinators, is fundamental to inform conservation efforts. This knowledge could be critical for prioritising efforts in human-dominated fragmented landscapes such as the world’s bio ersity hotspots, where reproductive success can be compromised due to habitat loss, limited access to pollinators or other factors. Yet, fundamental data on plant mating systems are lacking for many Australian plants. Here we determined the mating systems of native plant species growing in native woodland fragments within Perth’s urban landscape in south-western Australia. We manipulated insect access to flowers and pollen transfer on five locally common native species, then observed floral visitors and examined reproductive success. Hemiandra pungens and Patersonia occidentalis had mixed mating systems with some ability to self-pollinate, whereas Dianella revoluta and Jacksonia sericea were reliant on insects for outcross pollination. The fruits and seeds produced by Tricoryne elatior were too low to draw conclusions about its mating system. The introduced honey bee (Apis mellifera) was the sole visitor to the mixed mating species, whereas native bees visited D. revoluta and J. sericea (one bee species each). Overall, our data suggest that D. revoluta and J. sericea are more vulnerable to fragmentation than H. pungens and P. occidentalis. Although insects contributed significantly to the reproductive output of the two former plant species, our observations suggested low frequency and richness of insect visitors to these urban fragments. More research is required to determine the generality of our findings. A comparative study in larger native woodland fragments would help estimate the effect of fragmentation on insect pollinators and consequences for the insect-reliant plant species.
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/BT14237
Abstract: Serotiny is a mechanism for storing propagules on plants, so that seed dispersal can be maximised after the death of aerial parts of plants or to take advantage of conditions beneficial to establishment. In fire-prone vegetation, regeneration of new plants after fire is mostly from seeds that are stored in the soil or on the plant. These traits are generally consistent within a genus. However, in Conospermum, a genus of shrubs that mostly occur in fire-prone vegetation and in which most species have soil-stored seeds, two species exhibit an unusual serotinous structure. We examined the morphology and anatomy of inflorescences and infructescences of C. capitatum and C. petiolare that were collected from natural vegetation in south-western Western Australia. Inflorescence and infructescence axes were sectioned and examined microscopically, fresh infructescences were heated in an oven to various temperatures for 2 min and the fruits from them sown in a germination trial. Some fruits were also treated with smoke chemicals. Both species have a low, dense growth form and retain the seed-like fruits in a serotinous structure formed by enlargement of the cortical cells of the inflorescence axis after flowering. The fruits can be effectively released from the plant only if the foliage is removed by a fire. For both species, the infructescence protects the fruits from heat up to 200°C for 2 min and this is similar to protection afforded by woody cones in other serotinous species. C. capitatum requires either heat or smoke to cue germination, whereas C. petiolare requires no cue, as is found in most other serotinous species. A combination of morphological modification associated with allometry of the whole plant body and physiological changes to germination requirements shows that a series of complex changes may be needed to develop serotiny from non-serotinous antecedents.
Publisher: Oxford University Press (OUP)
Date: 09-05-2016
DOI: 10.1111/BOJ.12433
Publisher: Elsevier BV
Date: 02-2023
Publisher: CSIRO Publishing
Date: 1978
DOI: 10.1071/BT9780393
Abstract: The Lake Curlip sw is part of the Snowy River flats and is covered mainly by Phragmites grassland and Melaleuca thickets. The land bordering the flats is generally cleared, but there are some open-forests dominated by eucalypts, and small patches of Acmena closed-forest occur in sheltered sites on the flats or in gullies. Sediments from a core taken from the sw cover the period 5200 B.P. to present. From 5200 B.P. to about 1500 B.P., the pollen record shows very little change, but from 1500B.P. to the present, sw plant pollen proportions undergo marked fluctuations. Most of the sediments under the Lake Curlip sw were deposited under saline water pollen and spores in the sediments were derived mainly from the Snowy and Brodribb Rivers, which flowed into a large common estuary. After 1700 B.P., the water over the core site became fresher, hydrosere succession followed, culminating in the growth of a Melaleuca ericifolia closed-scrub. Water-borne pollen and spores were eliminated from the site, but have recently been reintroduced with flood waters from the Brodribb Channel. The pollen record from Lake Curlip sw suggests that there has been little change in the distribution of dry-land vegetation in this area. From this it must be concluded that the climate in the past 5200 years has been quite similar to that of the present.
Publisher: Informa UK Limited
Date: 03-2015
DOI: 10.1071/MU13113
Publisher: Wiley
Date: 24-02-2019
Publisher: Wiley
Date: 04-2004
Publisher: Elsevier BV
Date: 11-2003
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/BT01009
Abstract: The population structure and reproductive biology of the river oak (Casuarina cunninghamiana) were studied along the Murrumbidgee River on the Southern Tablelands of eastern Australia. The species has cone-like infructescences but is not serotinous, with samaras released when they are mature. Samaras were mostly distributed by wind close to female trees but were also carried by water. The first year of study (1985) appeared to be a mast year for seed production with much lower seed fall in the following year. Seedling establishment was spatially very variable, mostly under female canopies and appeared earlier on soil within the river channel than on the bank. Turnover was high and seedlings in the river channel generally died after being inundated. Most trees were within 3 m of the mean river level. However, the total distribution of adults was within the envelope of maximum floods in the area but establishment was not dependent on floods. The population structure was the result of yearly recruitment, although episodic events (floods, drought) may enhance or decrease establishment. Pot-trial results paralleled the field situation with substrate and water-table level not affecting germination of seed but strongly influencing seedling growth. Plants grew best on cobble substrates under a low water-table regime and poorly on cobbles with high water and sandy substrate under all water-table levels. Cobble banks seemed the best substrate for growth within the river channel and establishment may be prolific. Less-abundant seedling establishment occurred upslope but controls over this were not investigated.
Publisher: Springer Science and Business Media LLC
Date: 20-11-2022
Publisher: Wiley
Date: 12-06-2019
Publisher: Springer Science and Business Media LLC
Date: 02-01-2019
Publisher: Wiley
Date: 1979
Publisher: CSIRO Publishing
Date: 1979
DOI: 10.1071/BT9790185
Abstract: The site lies in a Sphagnum bog close to the Delegate River, which flows through sw vegetation (low open-forest, thicket or bog) bordered by tall open-forest or open-forest dominated by Eucalyptus species. The pollen diagram covers the period from about 12,000 B.P. to the present and indicates a change of dryland vegetation from an initial alpine herbfield or grassland to forest with a shrubby understorey, similar to that in the area today, by about 8000 B.P. During this time the sw vegetation changed from sw y heath to sedgeland and then to herbfield. After 8000 B.P. there is no indication of change in the dryland vegetation but, on the sw , herbfield gave way to Leptospermum and Baeckea riparian vegetation that was later replaced by the present Sphagnum bog community. At about 12,000 B.P. temperatures in the area were probably at least 5°C lower than they are today rainfall may have been less, but both temperature and precipitation had increased to present levels by about 8000 B.P.
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/BT06032
Abstract: Verticordia staminosa C.Gardner & A.C.George subsp. staminosa is an extremely rare shrub occurring as an isolated population of ~1200 plants on a granite outcrop in the semi-arid agricultural region of Western Australia, separated from its closest relative V. staminosa subsp. cylindracea by 400 km. We aimed to determine a hierarchy of causes for explaining the extremely restricted distribution of subsp. staminosa, and to determine the genetic relationships among populations within both subspecies. We measured allozyme variation in all known populations of the two subspecies. There were exceptionally high levels of genetic ergence between subsp. staminosa and subsp. cylindracea, including an apparent duplication of the gene encoding phosphoglucomutase, leading to an additional gene in subsp. cylindracea. These findings combined with UPGMA analysis indicate a very long period of historical separation, perhaps originating in the early Pleistocene. Genetic variation was partitioned mostly between rather than within populations, with very low levels of genetic variation within populations of both subspecies. For subsp. staminosa we quantified seed production for three consecutive years and demography for five consecutive years. We used transition matrix models to describe the shrub’s population dynamics and stochastic simulations to explicitly compare the effects of low rainfall and disturbance on population viability. Verticordia staminosa subsp. staminosa produces large numbers of seeds each year and has flower to fruit ratios greater than reported for related rare and common congeners. Seedling recruitment occurs in most years, with pulses in the wettest years. The mean finite population growth rate was 1.031. Elasticity analyses showed that population growth rate was more sensitive to stasis of established plants than to seedling recruitment. Population viability declined with lower rainfall and increased fire-related mortality of adult plants. Rarity in subsp. staminosa is best explained by evolutionary history and the interaction of climate change and disturbances such as fire that kill plants. Climatic fluctuations since the late Pliocene might have led to stochastic extinction episodes of populations on other granite outcrops, resulting in the currently restricted distribution. We discuss the implications of our findings for management of the species.
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/BT01041
Abstract: Acacia species 'Dandaragan' is known from one population confined to the Dandaragan–Badgingarra area in south-western Western Australia and is classified as critically endangered. Morphological and allozyme studies show that A. sp. 'Dandaragan' has close affinities with Acacia microbotrya Benth. sens. lat. and warrants taxonomic recognition at subspecies rank. A combination of floral and phyllode characters clearly separated A. sp. 'Dandaragan' and A. microbotrya s. l. by the presence of a discrete morphological boundary in the canonical variates plot and the high percentage of correct re-substitution classifications of in iduals into pre-defined taxa. UPGMA and maximum likelihood analyses of allozyme data distinguished A. sp. 'Dandaragan' and A. microbotrya s. l. Levels of genetic ersity were lower in A. sp. 'Dandaragan' than in A. microbotrya s. l. The size-class and lifestage structure of the A. sp. 'Dandaragan' suggests that the population is stable and possibly increasing in size predominantly by vegetative spread. The presence of a soil seed reserve and the ability to reproduce from root suckers suggests that A. sp. 'Dandaragan' is resilient to fire. Levels of innate seed dormancy were lower and tolerance to thermal shock higher in A. sp. 'Dandaragan' compared with A. microbotrya s. l. The population size, structure and germination ecology suggest that A. sp. 'Dandaragan' does not appear to have any immediate management requirements, apart from continued monitoring of adult plant health and recruitment. The study confirms that A. sp. Dandaragan should be recognised as Declared Rare (threatened) Flora and we recommend that the taxon's conservation status be reviewed.
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/BT01020
Abstract: Conostephium (Epacridaceae) has flowers that conform with a buzz-pollination syndrome but, unlike most plants with this form of pollination, the anthers are hidden within the corolla tube. Vibrations generated by bees grasping the apices of the corolla tubes must be transferred via short broad filaments to the anthers. The anthers do not have pores but each dehisces from the apex by a slit that elongates over the time the flowers take to senesce (up to 10 days). This may limit self-fertilisation as the stigma is receptive as soon as it appears from between the very short corolla lobes, so little pollen is released at first but later this would increase as the slit elongates. Visitation by pollinators has rarely been seen but several observations of native bees (Leioproctus and Lasioglossum) working the flowers are presented. The bees visit the nectarless flowers of Conostephium only for pollen and must forage at other kinds of flowers to obtain nectar. Pollen tubes occurred in the stigmas of most older flowers of C. pendulum, so pollen delivery does not seem to limit seed set. Despite this, the species sets few fruit. From examination of the taxonomic positions of likely buzz-pollinated taxa in the family, it appears that pollination by sonication has arisen independently several times in the Epacridaceae, with primarily two different floral configurations.
Publisher: Frontiers Media SA
Date: 2013
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/BT20026
Abstract: The Bass Strait islands are some of the few areas in Australia that were not occupied by humans at the time of European contact. There is archaeological evidence that Flinders Island at the eastern end of Bass Strait supported people until c. 4500 years ago but after that there is no evidence of human presence. Two previous pollen studies, covering the Holocene, from a sw on the eastern side of the island were interpreted rather differently in terms of how influential humans were in their effects on the island’s vegetation. In this paper, two short pollen diagrams from very different places than the earlier studies are described. These add to the evidence of the type of vegetation on the island over the late Quaternary. One diagram covers only the last 1500 years and is from a 1-m deposit from near the highest peak on the island in the south. This shows that there has been little change over that time in the vegetation around the site and there has been no influence of fire in the area. By contrast, a thin peat deposit, overlying lake sediments containing freshwater mollusc shells and Characeae oogonia, from Killiecrankie Bay in the north of the island dated at c. 34000 14C calibrated (cal) before present (BP) shows evidence of fire. The vegetation at the time was not similar to the vegetation during the Holocene with little representation of eucalypts but prominence of shrubby species (Leptospermum, Melaleuca) and herbaceous taxa such as Restionaceae and Asteraceae, particularly the Pleistocene Asteraceae pollen type. The vegetation on the eastern Bassian isthmus at that time was likely to have had less tree cover than in the Holocene and was more heath-dominated.
Publisher: CSIRO Publishing
Date: 1979
DOI: 10.1071/BT9790167
Abstract: Sw and forest vegetation on the Delegate River near Bendoc, at about 900 m above sea level in the highlands of eastern Victoria, was analysed by two different computer strategies-one agglomerative polythetic (MULTBET) and the other isive monothetic (DIVINF). Classification of the species with respect to sites by DIVINF (inverse) produced 10 meaningful species groups and a residue of relatively rare species. MULTBET (normal) produced the more satisfactory classification of sw and forest sites with respect to species, enabling 10 communities to be recognized: these are mapped and described. In general, the communities are characterized by a number of species groups and some groups are confined to particular parts of the study area. The main environmental features affecting the distribution of communities appear to be altitude above the valley floor and aspect for the forest and, for the sw , aeration and drainage of the soil, flooding (degree and duration) and low temperature.
No related grants have been discovered for philip ladd.