bluuebunny/crossref_metadata_2025 huggingface dataset:
Damage to Surface Roots of Eucalyptus marginata Trees at Sites Infested With Phytophthora cinnamomi
Authors: Davison EM , Tay FCS
Published: December 2005

Large surface roots from naturally occurring Eucalyptus marginata Donn ex Smith trees at two sites, part of each site being infested by Phytophthora cinnamomi Rands, were excavated to determine whether the number and/or size of pathogenic lesions could account for known differences in growth rate. There were no differences in the number of insect galleries, rots, number of phloem lesions or total lesion length per metre root length within different areas of the same site infested or uninfested by P. cinnamomi. Three P. cinnamomi and nine Cryphonectria cubensis (Bruner) Hedges lesions were found on more than 300 m of root length. It was concluded that these lesions are unlikely to result in significant differences in tree growth.
Pattern and Process in Alpine Vegetation and Landforms at Hill One, Southern Range, Tasmania
Authors: Lynch AJJ , Kirkpatrick JB
Published: December 2005

Hill One is a wind-exposed, alpine environment in southern Tasmania. The prevailing wind-stream is
westerly. However, high intensity south-westerly winds associated with frost events appear to control
the patterning of fjaeldmark. These winds cause necrosis of prostrate Richea scoparia and cushion
plants on their south-western side and induce migration of individual plants in a north-easterly
direction. Fjaeldmark is confined to the exposed mountain summit and terrace and step treads. Mosaic
cushion heath occurs in more exposed and poorly drained areas than other heath communities. The
horizontally bedded sediments of Hill One have been worked by erosional and depositional agents into
a complex morphology. Large terraces and non-sorted steps are likely to have formed from altiplanation
processes, that is, differential erosion of interbedded sediments, with accumulation of erosional debris at
the foot of the risers. Depositional lobes and erosional washout features are actively forming in
localised areas of concentrated drainage. The distribution of plant communities is closely associated
with rockiness, wind exposure and drainage.
Influence of Insect Herbivory on the Decline of Black Box (Eucalyptus largiflorens)
Authors: Stone C , Bacon PE
Published: December 2005

The contribution of insect herbivory to the canopy decline of Eucalyptus largiflorens F.Muell. (black box) was assessed on nine irrigated properties around Deniliquin in southern central New South Wales. Fully expanded leaves less than 1 year old were sampled from 36 mature trees in June 1993 and again in June 1994 after half the trees had been treated with a systemic insecticide in November 1993. Insect herbivory in treated trees fell significantly from 27 to 9%. It also fell, but to a lesser extent (28-19%, P < 0.05), in the untreated trees. The fall in insect herbivory in control trees corresponded to a decrease in rainfall in 1994 when the rainfall was 50% of that for 1993. There was a significant linear relationship between insect herbivory and trunk diameter increment in the untreated trees. There was no consistent relationship between insect herbivory and the visual assessment of crown condition. Although E. largiflorens is described as having both narrow adult and juvenile foliage, adjacent trees in this study differed significantly in their leaf length:breadth ratios. Canopies with a dominance of broader foliage had significantly higher levels of herbivory. Individual trees tended to replace foliage with leaves of similar morphology. It is suggested that this variation in leaf shape may be genetic rather than environmental. If so, landholders could select for trees with narrower foliage which may result in reduced impact of insect herbivory.
Distribution of the Orchid Mycorrhizal Fungus, Rhizoctonia solani, in Relation to Its Host, Pterostylis acuminata, in the Field
Authors: Perkins AJ , Mcgee PA
Published: December 2005

The plant pathology model was tested as an explanation of the distribution of orchid mycorrhizal fungi in the field. The mycorrhizal fungus, Rhizoctonia solani Kuhn AG 6, was isolated from adult plants and protocorms of Pterostylis acuminata R.Br. at a study site and from adult plants at five other locations in the Sydney region. In litter and trap seedlings, R. solani AG 6 was found within 50 cm of adult plants of the orchid P. acuminata and was more abundant close to the host plant. In the laboratory, protocorms of P. acuminata became infected with R. solani AG 6, but not with fungi isolated from the other orchids, P. concinna R.Br., P. ophioglossa R.Br. and Caladenia catenata (Smith) Druce, found at the site. It was concluded that the co-distribution model better explains the distribution of fungus and host in this case.
Floral Biology and Reproduction in Poa (Poeae: Gramineae)
Authors: Anton AM , Connor HE
Published: December 2005

Flowers in the cosmopolitan genus Poa L. are predominantly hermaphrodite but many departures from this sex form occur in the New World. Dioecism is primarily a South American breeding system with about three times as many dioecious species as in the rest of the world. Gynomonoecism is a Central and South American trait heavily represented in Andean Peru and Bolivia. This zone of gynomonoecism separates dioecism in North and South America. Gynodioecism, a convenient evolutionary position on the pathway to dioecism, is relatively infrequent and in North America is of indeterminate form in several taxa. Apomixis has long been recognised in European Pea; in western North America, apospory has invaded dioecious species and generated populations of pistillate plants. In Peru and Bolivia, several taxa are composed exclusively of plants with pistillate flowers, but these have arisen from gynomonoecious progenitors. Poa is of Eurasian origin and migrated to North America and thence to South America. Sex-form kinds and frequencies are in stark contrast in the two parts of the continent, but are explicable in evolutionary terms. The selection pressures generating the deviations from hermaphroditism and their timing are unknown.
In vitro Propagation of Nothofagus obliqua (Fagaceae).
Authors: Martinez Pastur GJ , Arena ME
Published: December 2005

Suitable culture conditions were investigated for in vitro propagation through shoot culture of seedlings and the acclimatization of the rooted plantlets of Nothofagus obliqua. Explant size and leaf expansion were critical for culture initiation. A medium with a low salt concentration and the addition of L-glutamine, as broadleaved tree medium, was suitable for shoot multiplication and it was influenced by both cytokinin and auxin. A multiplication rate of x5 has been obtained with 0.55 micro M benzyladenine (BA), and 0.09 micro M BA and 0.09 micro M IBA at day 63. Rooted shoots (51.9%) were obtained with 0.61 IBA and 1 week darkness at the induction stage. Rooted plants were then successfully acclimatised and 75% survival rate was obtained after 4 months.
RFLP and Rapd Analyses in the Identification and Differentiation of Isolates of the Leaf Spot Fungus Corynespora cassiicola
Authors: Silva WPK , Multani DS , Deverall BJ , Lyon BR
Published: December 2005

Genetic variabilty in isolates of the fungal plant pathogen Corynespora cassiicola cultured from pawpaw, mimosa and thyme hosts was assessed using restriction fragment length polymorphism (RFLP) analysis of internal transcribed spacer (ITS) regions of ribosomal DNA and random amplified polymorphic DNA (RAPD) analysis of total fungal DNA. Strains of Corynespora could be distinguished from a member of the closely-related genus Helminthosporium on the basis of amplified ITS fragment size, but could not be typed individually as the ITS regions of all isolates exhibited identical size and restriction endonuclease digestion pattern. However, RAPD profiles generated by 14 decamer primers of arbitrary sequence did reveal significant differences between some of the C. cassiicola isolates and succeeded in differentiating all but two of the strains. Cluster analysis of 218 amplified DNA fragments showed that the five isolates could be placed into three groups that correspond with their host origin and morphological characteristics. The use of these molecular techniques will be extended to assess intra-specific variation in C. cassiicola isolates from rubber trees in Sri Lanka, where highly pathogenic strains present a serious threat to the natural rubber industry.
Quantification of Cyanogenic Glycosides in Seedlings of Three Macadamia (Proteaceae) Species
Authors: Dahler JM , Mcconchie C , Turnbull CGN
Published: December 2005

Members of the genus Macadamia contain cyanogenic compounds, which release hydrogen cyanide (HCN) on hydrolysis. Concentrations of releasable cyanide were measured in tissues of mature nuts and seedlings of Macadamia integrifolia Maiden & Betche, M. tetraphylla L.A.S. Johnson and M. ternifolia F.Muell. Root, cotyledon and leaf samples were assayed at several developmental stages from germination to maturation of the first leaves. All samples contained detectable levels of cyanide. Concentrations were low (0.15 μmol g-1 fresh weight) in cotyledons of mature M. integrifolia and M. tetraphylla seeds, corresponding to the edibility of the seeds of these commercial species, and much higher (9.6 μmol g-1) in the inedible M. ternifolia seeds. Levels in cotyledons of all three species rose dramatically during germination. Root cyanide concentrations of 6-23 μmol g-1 were measured. The immature first leaf of the commercial species contained the highest concentrations (38-77 μmol g-1). Levels decreased with leaf maturity, correlating with toughening of the leaf and possibly a consequent diminished requirement for cyanide as a herbivory deterrent. The significance of the results with respect to plant-insect interactions is discussed.
Evidence for the Identity of the Hybrid, Eucalyptus 'brachyphylla' (Myrtaceae) From Morphology and Essential-Oil Composition
Authors: Grayling PM , Brooker MIH
Published: December 2005

The putative interspecific hybrid known as Eucalyptus brachyphylla C. Gardner, which is known to occur at two sites near Kalgoorlie, Western Australia, contains the non-terpenoid ester 4-methyl-2-pentyl acetate and the related alcohol 4-methylpentan-2-ol in its leaves. These compounds are otherwise known to occur in the leaves of only four Eucalyptus species and several putative interspecific hybrids. This, with the results of multivariate analyses of morphometric and oil composition data, adds considerable weight to;earlier suggestions that E. 'brachyphylla' is an hybrid of E. loxophleba Benth. and E. kruseana F. Muell. The presence at one site of two distinct chemotypes common to both parental species and to the hybrid plants is demonstrated and discussed.
Demonstration of Pollinator-Mediated Reproductive Isolation in Sexually Deceptive Species of Chiloglottis (Orchidaceae: Caladeniinae)
Authors: Bower CC
Published: December 2005

Three designs of field choice experiments were used to demonstrate complete reproductive isolation by sexually deceived thynnine pollinators (Neozeleboria Rohwer spp.) in eight species of Chiloglottis R.Br. Four species, Chiloglottis diphylla R.Br., C. formicifera Fitzg., C. pluricallata D.L.Jones and C. valida D.L.Jones, attracted only one wasp species, but the other four, C. platyptera D.L.Jones, C. seminuda D.L.Jones, C. trilabra Fitzg. and C. reflexa Labill. Druce exhibited multiple species attraction. Wasps visiting orchids were classified as major responders if they exhibited behaviour which could potentially result in pollination, by contrast to minor responders which did not. Major responders occurring sympatrically with the orchid were termed confirmed, potential or putative pollinators on the basis of observation of pollinia removal or deposition, pseudocopulation with the labellum, or arrival at bait flowers with pollinia from local orchid populations, respectively. Each Chiloglottis species had a single Neozeleboria species as confirmed or potential pollinator. The data confirmed that field pollinator choice tests can be used to distinguish cryptic sexually deceptive orchid species, and that specific pollinators may be used reliably as taxonomic characters in Chiloglottis.
Ecotyptic Differences in the Flowering of Pimelea ferruginea (Thymelaeaceae) in Response to Cool Temperatures.
Authors: King RW , Pate JS , Johnston J
Published: December 2005

Pimelea ferruginea Labill., a spring-flowering woody perennial from Western Australia, is distributed
coastally from Albany (latitude 35° 11̸2S) to just below Geraldton (latitude 29° 07̸2S). Clones developed
from cuttings, taken from single plants of Pimelea ferruginea at sites covering the range of its
distribution, were grown vegetatively for up to 6 months in a naturally lit glasshouse and then
transferred to a range of temperatures for induction of flowering. Selections from cooler, southerly sites
(33-3.5°S latitude) flowered with a low temperature optimum (12-15°C average) but remained
vegetative at a 3°C higher temperature (18°C). By contrast, northerly selections (29-30°S latitude)
tolerated 3-5°C warmer conditions for their flowering. Daylength effects were of minor importance
relative to the response to cool temperature with short (10 h) days being marginally more favourable
than long days (16 h). In the wild, Pimelea ferruginea flowers in spring (September-October) after
experiencing winter temperatures comparable to those effective in controlled environments. To define
field flowering response, at the beginning of winter, vegetative six-month-old plants of the various
selections were transferred to a southerly, intermediate or northerly field nursery site in Western
Australia. The differences in flowering response across sites and selections broadly matched the
temperatures needed for flowering of the selections in controlled environments. These physiological
differences in regulation of flowering indicate ecotypic adaptation to temperature over the latitudinal
range of distribution of this species of Pimelea. The field transfer experiments highlight the overriding
inductive effect of cool winter temperatures in determining flowering time. Furthermore, any rise of
2-4°C in winter temperature due to global warming could have serious consequences for floral
initiation and for survival of P. ferruginea.
Conservation of the Grassy White Box Woodlands: Rangewide Floristic Variation and Implications for Reserve Design
Authors: Prober SM
Published: December 2005

Grassy white box (Eucalyptus albens Benth.) woodlands once covered several million hectares of the
wheat-sheep belt of south-eastern Australia. The pre-European floristic composition of these woodlands
is little-known, as almost all of them were rapidly cleared for cropping or modified by livestock
grazing. Woodland remnants were surveyed across NSW, to describe rangewide variation in the
woodland flora, and to provide a basis for reserve design. As far as could be detected from current
remnants, some of the major features of the original grassy white box woodland understorey appear to
have been relatively constant across NSW: on a wide variety of soils and parent materials from southern
to northern NSW, the dominant native grasses in little-disturbed sites were generally Themeda australis
(R.Br.) Stapf andor Poa sieberiana Sprengel, and many of the subsidiary herbs and grasses occurred
across this range. There were, however, several natural patterns of variation requiring consideration in
conservation planning: about half of the subsidiary herb and grass species showed a relationship with
latitude, probably relating to a climatic gradient; the understorey became more shrubby, with a sparser
and more varied grass component, on soils classed as being 'unsuitable for agriculture'; and on basalt
parent materials of the Inverell Plateau, Dichanthium sericeum (R.Br.) A.Camus may have been a more
prominent component of the understorey. Natural floristic variation was overlain by patterns resulting
from European disturbance, as indicated by floristic distinctions between sites of differing landuse.
While these distinctions were partly related to poorer soil resource class in State Forests and Nature
Reserves, grazing by livestock and tree clearing are likely to to have contributed to them. Reserves in
ine whire box woodiands are presentiy few, and are not representative of the naturai variation. ~ o s t
existing reserves occur on soils unsuited to agriculture, compared with the grazing or arable land of
typical grassy woodland. Cemetery remnants, rail easements, Travelling Stock Reserves and roadsides
provide the best opportunities for conservation on higher-quality soils. Remnant quality declined
significantly in southern NSW, indicating a need for greater conservation effort in southern areas.
Impact and Disease Centre Characteristics of Phytophthora cinnamomi Infestations of Banksia Woodlands on the Swan Coastal Plain, Western Australia
Authors: Shearer BL , Dillon M
Published: December 2005

Phytophthora cinnamomi Rands was isolated from either dead plants or soil at 46 disease centres in
Banksia woodland at national parks and reserves on the Swan Coastal Plain. Phytophthora cryptogea
Pethybridge & Lafferty was also isolated from roots of dead Acacia pulchella R.Br. in one disease
centre infected with P. cinnamomi. Dead plants were infected with Armillaria luteobubalina Watling &
Kile in four disease centres on the Spearwood Dune System, and these centres were excluded from
further analysis. Phytophthora cinnamomi diseased areas ranged from 0.01 to 30 ha in size (mean 1.6 ±
s.e. 0.7 ha). The total area infested for the 46 disease centres was 71.5 ha. Impact of P. cinnamomi was
high in 17% of disease centres and low in 11% of disease centres. Age of plant death was a mixture of
old and recent in 85% of disease centres. Mainly old deaths occurred in only 4% of disease centres. The
proportion of species dying in infested areas varied between 10-64% (mean 28 ± s.e. 2%) and was
positively correlated with impact type. It was found that infestation decreased species number; on
average, there were seven fewer species in infested compared to non-infested areas. Four plant species
associated with moist sandy sites tended to occur more frequently in centres of high impact than by
chance alone. Occurrence of P. cinnamomi was related to soil association with soils of 60% of the
disease centres belonging to the Bassendean or Southern River associations of the Bassendean Dune
System. Sixteen percent of disease centres occurred in the Cannington, Guildford and Serpentine River
associations of the Pinjarra Plain. No disease centres of P. cinnamomi were found on soils of the
Speanvood and Quindalup Dune Systems. A water table was found within 3 m of the soil surface in
48% of the centres. Disturbance was associated with all disease centres. Firebreaks were associated with
72% of disease centres. Banksia woodland remnants on the Bassendean Dune System and the Pinjarra
Plain are highly vulnerable to infection by P. cinnamomi and their conservation requires control of
existing infestatinns and protection from introduction af the pathogen.
Patterns of Flowering and Seed Production in Eucalyptus miniata and E. tetrodonta in a Tropical Savanna Woodland, Northern Australia
Authors: Setterfield S , Williams RJ
Published: December 2005

The reproductive phenology-the annual and spatial variation in tree fecundity, ovule development and seedfall-of Eucalyptus miniata Cunn. ex Schauer and E. tetrodonta F. Muell. is described at a tropical savanna site in northern Australia from 1992 to 1994. There was substantial inter-annual variability in fecundity of both species at the individual and the population level. The proportion of ovules which survived did not vary significantly between years. Seed production and seedfall varied substantially between years with large seed yields in 1994 and low seed yields in 1993. Eucalyptus miniata and E. tetrodonta are separated in time (by 2-8 weeks) with respect to peak periods for all key phenology events-budding, flowering and seedfall. Both species are non-serotinous with all seed shed within 8 months of ovule initiation. Peak seedfall occurred up to 1 month before the first wet season rains for E. miniata and coincided with these rains for E. tetrodonta. Post-dispersal conditions for germination and establishment are more likely than seed supply to limit seedling establishment of E. miniata and E. tetrodonta.
Effects of Seed Dormancy and Emergence Time on the Survival and Early Growth of Eucalyptus delegatensis and E. amygdalina
Authors: Battaglia M
Published: December 2005

Seed of two tree species, Eucalyptus amygdalina Labill. and E. delegatensis R.T.Baker, was sown on 12 separate dates at two sites close to which both occurred. The species have parapatric distributions but form ecotonal stands. One site was harsh by comparison to the other. Recruitment, survival and growth were recorded at regular intervals following sowing and were related to temperature and soil moisture. The non-dormant seed fraction of both species responded similarly to environmental cues, with rapid emergence occurring when the mean daily temperature exceeded 6°C and the soil moisture index was below 30 mm. Differences in the pattern of emergence between the species resulted from differing degrees of seed dormancy. On the harsh site, spring emergence gave superior survival and growth than did autumn emergence. Consequently, spring emergents were dominant at the end of the experiment. At the milder of the two sites, little difference in survival or growth was observed between emergence times and consequently seedlings emerging in the autumn were dominant at the end of the experiment. Differences between the mortality rate of very young seedlings of each species were detected at some times of year. The combination of differences in seedling mortality, and patterns of emergence as a result of seed dormancy suggest that differences in the regeneration niche may act to reinforce species boundaries, and combined with spatial and temporal variation in regeneration conditions may promote coexistence in ecotonal stands.
Leaf Orientation in Juvenile Eucalyptus camaldulensis
Authors: James SA , Bell DT
Published: December 2005

Leaves of six genotypes of Eucalyptus camaldulensis Dehnh. from five Australian locations were
compared. The juvenile plants were approximately 6 months old, an age related to field planting times
in salinised and waterlogged agricultural catchments. The leaves of juvenile plants of Eucalyptus
camaldulensis do not exhibit solar-tracking, but leaf orientation is believed to maximise solar radiation
absorption. Through vertically-tilted leaves and rotated leaf blade orientation, replicate clonal plantlets
from Erudina, SA, potentially absorbed at mid-morning, mid-day and mid-afternoon, an average of
71%, 15% and 74%, respectively, more photosynthetically active radiation than a theoretical plant with
horizontal, non-self shading leaves during spring. This clone intercepted, on average, between 67% and
76% of all the solar radiation potentially intercepted if all leaf blades faced the sun throughout the day
and no leaf shading occurred. Clonal plantlets from Silverton, NSW, and Dongara, WA, also displayed
leaf orientations that showed greater radiation interception compared to a theoretical plant with
horizontal leaves. Two genotypes from Wooramel, WA, and a genotype from Murray Bridge, SA,
showed a 13-24% reduction in interception in the middle of the day compared to the theoretical plant
with all horizontal and non-shading leaves, but 15-96% more radiation during the morning and evening
through leaf orientation. Morphological and anatomical leaf characteristics of these clones tended to
show characteristics typical of 'sun-leaves', or leaves developed under high light conditions. The
Erudina, SA, and Silverton, NSW, clones, having the greatest potential light interception through leaf
orientation, produced leaves with a more glaucous, light-reflective surface. Glaucescence may protect
against too much light being absorbed by the leaves of these clones. Variation in the degree of
orientation of leaves in these six genotypes of E. camaldulensis indicates that it could be possible to
select clones which maximise energy utilisation during periods of lower light availability and, hence,
have enhanced growth and survival in early stages of establishment.
Genetic Diversity, Mating System and Systematic Relationships in Two Red Mahoganies, Eucalyptus pellita and E. scias
Authors: House APN , Bell JC
Published: December 2005

Isozyme variation in two closely related red mahoganies (Eucalyptus pellita F. Muell. and E. scias L.A.S.Johnson and K.D.Hill) was examined in 17 populations of E. pellita from Australia, Papua New Guinea and Indonesia and 8 of E. scias (including all 3 subspecies) from south-eastern coastal Australia. Measures of genetic diversity and relationships between species and subspecies were based on 15 variable loci. Both E. pellita and E. scias had moderately high levels of genetic diversity, comparable to other similarly distributed species. Most genetic diversity within each species was found within populations (80% in E. pellita and 83% in E. scias). There were substantial allelic differences between the species at several loci; the populations clustered into groups corresponding to the two species. Yet genetic differentiation between the two species was relatively low, and the three subspecies of E. scias were not well separated. Outcrossing rates in E. pellita are variable, with low rates (<50%) measured in populations from Irian Jaya and Cape York Peninsula, and 73% in a population from northeast Queensland.
Variation in Populations of Tribulus terrestris (Zygophyllaceae) .1. Burr Morphology
Authors: Scott JK , Morrison SM
Published: December 2005

Variation in bun morphology was investigated as part of a study to identify the origins of the widespread weed and potential biological control target Tribulus terrestris L. s.1. (Zygophyllaceae). Measurements were made of four size variables, four spine angles and the number of seeds in each bun from 31 Australian and overseas collection sites. Cluster analysis using all variables (valid for 26 collection sites) identified four groups of burrs, one of which contained a single site from Israel that differed due to the angle of the spines. All 31 sites were included by removing the measurement of the basal spine, which is sometimes absent from burrs. Four clusters were found on reanalysis. The minimum number of variables that produced the four clusters were length and width of burrs and abaxial spine length. Most southern Australian sites were grouped with southern African, Indian and Israeli sites. Three Western Australian sites formed one group, as did Northern Territory and Queensland sites. A fourth group included one site each from Australia, Iran, Israel and USA. The relationship between base length and width of the bun distinguished the probably native northern Australian collections, which have either more squat or more elongate burrs, from the probably introduced populations of T. terrestris in southern Australia. However, analysis of morphological variation only approximately detected groupings within the southern Australian and overseas collections that were subsequently identified by isozyme and cytogenetic studies.
Variation in Populations of Tribulus terrestris (Zygophyllaceae) .2. Chromosome Numbers
Authors: Morrison SM , Scott JK
Published: December 2005

Variation in chromosome number was investigated as part of a study to identify the origins of the widespread weed and potential biological control target Tribulus terrestris L. s.1. (Zygophyllaceae). Three ploidy levels, tetraploid 2n = 24, hexaploid 2n = 36 and octoploid 2n = 48, were detected in 24 Australian and 24 overseas collections. Northern Territory and Queensland collections, possibly representing a native species of Tribulus, had counts of 2n = c. 24. The majority of collections of T. terrestris in southern and north-western regions of Australia had counts of 2n = c. 36, but two collections had counts of 2n = c. 24. Collections from South Africa and Namibia also had a mixture of tetraploid and hexaploid forms. The USA, Mediterranean and West Asian samples (except for three Kuwait samples) were all hexaploid. All Indian and three Kuwait samples were the only octoploid collections observed. These ploidy levels agree with those previously reported for T. terrestris. It was concluded that the polyploid complex has an allopolyploid origin. The predominantly hexaploid collections in Australia indicate an overseas origin, and the presence of two tetraploid collections points to two or more separate introductions of T. terrestris into Australia. Counts for T. micrococcus and T. occidentalis were 2n = c. 48, which provide further evidence for a base number of x = 6 or 12 for the genus.
Variation in Populations of Tribulus terrestris (Zygophyllaceae) .3. Isozyme Analysis
Authors: Morrison SM , Scott JK
Published: December 2005

Isozyme variation in seedlings was investigated as part of a study to identify the origins of the widespread weed and potential biological control target Tribulus terrestris L. s.1. (Zygophyllaceae). Seedlings were obtained from 30 Australian and 24 overseas collections of burrs. Polymorphism was detected in 8 of the 11 putative loci scored. Queensland and Northern Territory collections differed from other Australian and non-Australian collections, indicating that they belong to a separate and possibly native Australian species. Other Australian collections had a high genetic similarity to burrs obtained from the Mediterranean, West Asia, South Africa, Namibia and the USA, the latter being an introduced population. Two Namibian collections formed a separate group and it is possible that southern Africa, like Australia, has native and introduced plants of T. terrestris. All Indian and two Kuwait collections were grouped together and had little similarity with any other group. Tribulus terrestris in southern Australia is most likely to have originated in the Mediterranean or West Asian region.
Dormancy in Seeds of Hibbertia hypericoides (Dilleniaceae)
Authors: Schatral A
Published: December 2005

Seeds of Hibbertia hypericoides (DC.) Benth. (Dilleniaceae), a shrub native to the south-west of Western Australia, exhibit both seed coat dormancy and embryo dormancy. Water uptake was passive and germination poor after an experimental time period of 3 months in mature, potentially viable seeds. After removal of the seed coat, imbibition occurred in three phases and resulted from passive hydration and active metabolic processes. In mature, potentially viable seeds low water uptake is due to the heavily cutinised cells of the endotesta, since immature, potentially viable seeds and non-viable seeds, which both have a weakly cutinised endotesta, imbibed water readily. Removal of the seed coat significantly increased the final germination percentage in potentially viable seeds. However, the low proportion of vigorous seedlings after seed coat removal suggests that the minute, underdeveloped embryo itself is dormant. Seed coat removal therefore appears to lead to the precocious germination of immature, presumably still partly dormant embryos. Gibberellic acid (GA3) did not affect the germination of seeds. Preliminary experiments do not suggest that the seed coat contains chemical inhibitors.
Distribution and Floristics of Bryophytes in Soil Crusts in Semi-Arid and Arid Eastern Australia
Authors: Eldridge DJ , Tozer ME
Published: December 2005

A total of 56 bryophyte taxa associated with biological soil crusts was collected from 282 sites in semi-arid and arid eastern Australia. The 41 moss taxa and 15 liverwort taxa found were dominated by the families Pottiaceae and Ricciaceae respectively. Bryophytes were present at 224 of the 282 sites, and their distribution varied widely according to different landscapes. The mean number of taxa per site ranged from 8.9 on plains with red earths to 2.1 on active floodplains. The most common bryophytes found in the survey area were Bryum pachytheca, Didymodon torquatus, Gigaspermum repens, Goniomitrium enerve, Desmatodon convolutus, Stonea oleaginosa, Crossidium davidai, Riccia limbata and Riccia lamellosa. In this paper, the distribution of bryophytes in relation to landscape types, and some strategies for surviving in arid environments and their roles in biodiversity and rangeland condition assessment are discussed. Their distribution is compared with other published and unpublished studies from similar areas of Australia.
Transpiration by Trees From Contrasting Forest Types
Authors: Barrett DJ , Hatton TJ , Ash JE , Ball MC
Published: December 2005

Temperate rainforests and eucalypt forests of coastal south-eastern Australia are distributed
differentially with aspect. Rainforests, in which Ceratopetalum apetalum D.Don and Doryphora
sassafras Endl. are the dominant tree species, occur on slopes of southerly aspect and along gully
bottoms, whereas eucalypt forests, dominated by Eucalyptus maculata Hook., occur on upper slopes of
northerly aspect and on ridge tops. Whether transpiration rates of trees differed across the
rainforest-eucalypt forest boundary on north and south facing aspects was tested by measuring stem sap
flow in trees in a single catchment during winter, summer and autumn. Differences in transpiration rate
by trees in these stands were due to various combinations of biological and physical factors. Firstly,
mean maximum transpiration rate per tree (crown area basis) was greater in rainforest on the gully
bottom where deep soil water from down-slope drainage was greater than in eucalypt forest located
upslope on the northern aspect. By contrast, there was no difference between maximum transpiration
rates in rainforest and eucalypt forest on the southern aspect. Variation in transpiration rate between
seasons was not related to variation in surface soil moisture content (< 0.35 m depth). Secondly,
transpiration rates per unit crown area in rainforest at the gully bottom were associated with higher leaf
area indices than upslope on the northern aspect. However, in rainforest upslope on the southern aspect,
higher transpiration rates were not associated with higher leaf area indices. Thirdly, trees in eucalypt
forest maintained similar sapwood moisture contents in summer as in winter and autumn, whereas
sapwood moisture contents declined in rainforest trees in summer, suggesting that eucalypts had access
to water from deep within the soil profile which was unavailable to more shallow rooting rainforest
trees. Fourthly, higher modal and maximal sap velocities in eucalypt trees were partly due to wider
xylem vessels and resulted in faster maximum sap flow and greater daily total water use in all seasons
on both aspects than in rainforest species. Finally, as atmospheric demand for water increased from
winter to summer, transpiration rates were mediated by stomata1 closure as indicated by lower average
midday shoot conductance to water vapour during summer than other seasons. The interaction between
microenvironment, which deteimines water availability, and physiological attsibutes, which determine
tree water acquisition and use, may contribute to the differential distribution of rainforest and eucalypt
forest with aspect in south-eastern Australia.
An Examination of the Drought and Frost Tolerance of Banksia marginata (Proteaceae) as an Explanation of Its Current Widespread Occurrence in Tasmania
Authors: Blake J , Hill RS
Published: December 2005

Populations of Banksia marginata Cavanilles from sea level to 1040 m above sea level near Hobart were examined for frost and drought tolerance to determine the extent of the inter-population variation and physiological plasticity of this species. This study was designed to give some insight into the reasons behind the successful occupation of a wide range of habitats by B. marginata in Tasmania today. All populations were highly frost tolerant, irrespective of season, with the peak tolerance usually occurring in summer, suggesting a link to some other physiological aspect such as drought tolerance. Water relations results were complex and highly variable among the populations. For the highest altitude population at least it is probable that cell elasticity and high apoplastic water contents, rather than osmotic adjustment, assist in frost and drought tolerance. It is likely that the physiological plasticity and apparent genetic diversity exhibited by these populations assisted the survival of B. marginata in pockets of refugia throughout Tasmania during past climatic upheavals during glacial and interglacial cycles.
Anatomical Adaptive Strategies to Flooding and Rhizosphere Oxidation in Mangrove Seedlings
Authors: Youssef T , Saenger P
Published: December 2005

Limited information exists on the relation between the capacity of mangrove seedlings to oxidise the rhizosphere and their differential waterlogging tolerance. Laboratory experiments were conducted to estimate radial oxygen loss (ROL) by the entire root, the area of oxidising sites (AOS) on the root surface, root porosity (POR), and the internal diffusive resistance in the ground tissue of seedlings of six mangrove species that show a differential response to flooding. Radial oxygen loss was extremely low in all viviparous seedlings (0.7-1.5 μmol O2 per cm2AOS per day). Differential tolerance of species coincided with the degree of porosity (14.8-45.7%) and the ability of seedlings to develop barriers to oxygen leakage on the root surface. The percentage area of lacunae in the ground tissue of seedlings of the four viviparous species revealed a constriction of the air flow path at the hypocotyl junction. These findings suggest that: (i) the differential tolerance to waterlogging in mangrove seedlings is not simply based on their ability to oxidise the rhizosphere; (ii) the high diffusive resistance in the hypocotyl junction is likely to affect root aeration when the plant's access to air is limited by partial or total submergence; and (iii) waterlogging tolerance is probably a function of the strategy by which roots conserve oxygen to maintain aerobic metabolism for longer periods during submergence. Implications of these findings in seedlings are discussed in relation to other anatomical and morphological adaptations to waterlogging in mature mangroves.
Conservation and Genetic Diversity of Microsatellite loci in the Genus Eucalyptus
Authors: Byrne M , Marquezgarcia MI , Uren T , Smith DS , Moran GF
Published: December 2005

Four microsatellite loci have been characterised in Eucalyptus nitens Maiden and in six other eucalypt species. The dinucleotide repeats were identified by screening a Sau3AI genomic DNA library from E. nitens with (CA)n and (GA)n oligonucleotide probes and sequencing the positive clones. Genetic analysis of 20 unrelated individuals from five populations of E. nitens showed all loci to be highly polymorphic with an average of 9.5 alleles per locus and an average heterozygosity of 0.575. Analysis of four individuals from each of six species from three subgenera showed complete conservation of microsatellite loci between species within the same subgenus, Symphyomyrtus, and conservation of 50% of loci across species between the two main subgenera, Symphyomyrtus and Monocalyptus. None of the primers amplified microsatellite loci in Eucalyptus maculata from the subgenus Corymbia. All microsatellite loci that were detected were polymorphic. Highly polymorphic microsatellite loci that are conserved across species will be useful for mapping quantitative traits, fingerprinting breeding lines, and for within-population studies requiring fine-scale analysis of genetic variation.
An Improved Embryo-Rescue Protocol for a Carica Interspecific Hybrid
Authors: Magdalita PM , Adkins SW , Godwin ID , Drew RA
Published: December 2005

An improved embryo-rescue protocol was developed for embryos (90 days old) of Carica papaya L. (Clone 2001), and subsequently was utilised for efficient production of interspecific hybrids of C. papaya × C. cauliflora Jacq. from 90- to 120-day-old embryos. Pre-incubation of C. papaya embryos for 7 days on a germination medium containing half-strength De Fossard nutrients supplemented with gibberellic acid (10 μM), 6-benzylamino-purine (0.25 μM), alpha-naphthalene-acetic acid (0.25 μM). sucrose (58 mM) and agar (8 g L-1) supported 100% germination. Subsequent transfer of germinated embryos to a nutrient medium that was identical, except that it was free of plant growth regulator, allowed good growth but induced shoot etiolation and callus production. Reducing the pre-incubation of C. papaya embryos on this medium to 5 days before transfer to the medium free of plant growth regulator produced similarly high germination (96%), but allowed for the production of good quality seedlings that were unetiolated and free of unwanted callus. For interspecific hybrids, a 5-day pre-incubation of the embryos on a liquid formulation was better than the solid formulation as it promoted better growth and vigour of the normally abortive interspecific hybrid embryos. Using the improved protocol, 1981 of 2100 (94%) interspecific hybrid embryos consisting of single and multiple forms were germinated. In all cases, the germinating multiple embryos underwent further embryogenesis that allowed for the production of 485 (25%) morphologically normal hybrid plants grown in soil in the glasshouse.
Vegetation Changes Associated With Phytophthora cinnamomi and Its Decline Under Xanthorrhoea australis in Kinglake National Park, Victoria
Authors: Duncan MJ , Keane PJ
Published: December 2005

Changes in the species composition associated with the presence of Phytophthora cinnamomi Rands
and changes in the potential activity of the fungus were measured at a dry sclerophyll forest site in
Kinglake National Park. In soil infested with P. cinnamomi, both the percentage cover and density of
the major overstorey species (Eucalyptus dives Schauer in Walp. and E. macrorhyncha F.Muell.) and
major understorey species (Xanthorrhoea australis R.Br., Daviesia ulicifolia Andrews and Dillwynia
phylicoides Cunn.) were significantly reduced, while both the cover and density of the sedge species
(Gahnia sieberiana Kunth., Lepidosperma laterale R.Br.and L. semiteres F.Muell.) increased
significantly. The density of the major grass species, Chionochloa pallida (R.Br.) S. W. L.Jacobs, did not
change. Species that were susceptible to P. cinnamomi showed varying patterns of decline.
Xanthorrhoea australis was the most sensitive to the presence of P. cinnamomi, showing an immediate
and large decline in both percentage cover and density, while Daviesia ulicifolia was the least sensitive,
showing a decline only at later stages of disease development in the vegetation. Lepidosperma laterale
and L. seiiziteres were the major colonisers of the diseased vegetation at this site, and were succeeded by
Gahnia sieberiana, which became the dominant sedge species in the diseased zone after the dead plants
of X. australis had collapsed. A seasonal survey (1992-1994) of P. cinnamomi found the pathogen to be
potentially active all year round at this site, with summer and winter maxima. A decline was measured
in the potential activity of P. cinnamorni underneath diseased and dead plants of X. australis after a
disease outbreak. The potential activity of P. cinnamomi was greatest in soil collected from the base of
dying plants of X. australis and zero in soil from under dead and collapsed individuals of that species. A
similar pattern of decline in the potential pathogen activity was measured for the same host species at
disease sites in the Brisbane Ranges National Park and Angahook State Park. A similar consistent
pattern of decline in the disease potential of P. cinnamomi in soil from under diseased and dead plants
of X. australis was observed in a pot bioassay. This decline in disease potential was overcome by the
addition of Eucalyptus sieberi L.A.S.Johnson seedlings and P. cinnamomi inoculum to the soil.
Litterfall in Casuarina glauca Coastal Wetland Forests
Authors: Clarke PJ , Allaway WG
Published: December 2005

Litterfall was measured over 3 years at two sites in coastal wetland forests dominated by Casuarina glauca Sieb. ex Spreng. in New South Wales. One site was in an incised river valley adjacent to the Hawkesbury River estuary, and the other site was in an open embayment adjacent to Botany Bay. Branchlets were the major litter component, followed by stems and infructescences. Significant year to year variation in branchlet fall correlated with storm events in one year. Overall, no significant differences in annual total litterfall were detected among sites and, averaged over all sites and years, the mean annual litterfall was 848 g m-2. This suggests that coastal wetland forests dominated by C. glauca have some of the highest recorded annual litterfall rates for Australian temperate and subtropical forests. A flood event in the river valley site removed about 75% of the standing litter accumulated on the forest floor prior to flooding (1244 g m-2). This suggests that accumulated organic matter and nutrients can be directly transported to estuarine ecosystems. Under non-flood conditions, however, these forests appear to act as organic matter and nutrient sinks.
Photosynthetic Responses to Drought Conditions in Three Coastal Dune Plants in Relation to Their Zonal Distribution
Authors: Ishikawa SI , Furukawa A , Oikawa T
Published: December 2005

Species-specific responses of three coastal dune plants to drought conditions were examined to investigate the causal relationship between drought tolerance and plant distribution in coastal dune regions. Measurements of net photosynthetic rates were undertaken in two meteorologically contrasting years, 1989 and 1990; the summer of 1990 was characterised by long rainless periods, whereas the meteorological conditions of the summer months in 1989 did not differ significantly from the average values. The reductions of net photosynthetic rates caused by the 1990 summer aridity differed widely among the three species. Net photosynthetic rate (Pn) of Ischaemum anthephoroides, a C4 plant, distributed in hind dunes, fell to only 33-43% of the values in the same season in 1989. By contrast, those of Carex kobomugi and Calystegia soldanella, which were generally growing in more seaward sites, were 67-87% and 76-97%, respectively. In July 1990, Pn of Ischaemum anthephoroides was significantly lower than that of the other two species. Ischaemum anthephoroides showed the most pronounced reduction of leaf water potential, which was as low as -2.5 MPa, while the leaf water potentials of Calystegia soldanella and Carer kobomugi remained around -1.5 and -2.0 MPa, respectively, in the 1990 summer period. Such a low tolerance to drought of I. Anthephoroides is attributed to the shallow distribution of the root system. These findings are considered to be among reasons why I. anthephoroides is restricted to the inland area, where drought conditions are milder than in seaward areas.
The Relationship Between Distance From Water and the Soil Seed Bank in a Grazed Semi-Arid Subtropical Rangeland
Authors: Navie SC , Cowley RA , Rogers RW
Published: December 2005

The germinable soil seed bank of a grassy Eucalyptus populnea F.Muell, open woodland was investigated in relationship to distance from water (away from a bore-drain) on North Yancho Station, near Bollon in southern semi-arid Queensland. The germinable soil seed bank was both diverse and abundant, 69 taxa of seedlings being identified to species and 2 more to genus. A mean density of 13 207 ± 4160 seeds m-2 was recorded, with over 80% of the seed being from the annual forbs Crassula sieberana (Schultes & J.H.Shultes) Druce, Wahlenbergia tumidifructa P.J.Smith and Dysphania gomulifera (Nees) Paul G.Wilson. Most common species showed spatial variation in their germinable seed density with relation to distance from water, resembling the patterns previously reported by other authors for standing vegetation under stocking pressure gradients.