bluuebunny/crossref_metadata_2025 huggingface dataset:
Lipolytic responses to catecholamines in ractopamine-treated pigs
Authors: Leury B. J. , Dunshea F. R. , King R. H.
Published: August 2004

The β-agonist ractopamine (RAC) promotes protein deposition with little
effect on fat deposition in the pig. To assess whether the lack of effect on
fat deposition was due to changes in response to catecholamines, crossbred
pigs with venous catheters were used to examine plasma non-esterified fatty
acid (NEFA) concentrations before and after intravenous (i.v.) injections of
the (β1+β2)-agonist
isoproterenol and the β2-agonist fenoterol during
dietary RAC (0 or 20 mg/kg) treatment. In Expt 1, gilts received
increasing i.v. doses of fenoterol [3, 9, 27, 81, and 243 µg/kg
bodyweight (BW)] on Day 34 and blood samples were taken for metabolite
analyses. The protocol was repeated on Day 36 but this time using increasing
doses of isoproterenol (0·11, 0·33, 1, 3, and 9 µg/kg
BW). Dietary RAC decreased basal NEFA concentrations but had no effect on
plasma glucose concentrations. When the individual NEFA responses to fenoterol
curves were fitted, the derived values for maximal response
(Rmax) suggested that there was no difference between
pigs fed 0 or 20 mg/kg RAC (1739 v. 1847
µmol/L, P = 0 ·829). However,
there was an almost 10-fold increase in the dose of fenoterol required to
elicit a NEFA response 50% of Rmax (ED50) in
RAC-fed pigs (11·6 v. 107·0
µg/kg, P = 0·008). Intravenous
fenoterol challenge increased plasma glucose linearly but this response was
not altered by dietary RAC. In Expt 2, gilts received increasing i.v. doses of
fenoterol (16, 80, and 400 µg/kg BW) on Day 10 and blood samples
were taken for metabolite analyses. The protocol was repeated on Day 11 but
this time using increasing doses of isoproterenol (6·25, 32·5,
and 162·5 mg/kg BW). The derived values for
Rmax suggested that there was no effect of injected
β-agonist (2209 v. 2405 µmol/L for
fenoterol and isoproterenol, respectively, P =
0·204) or dietary RAC (2251 v. 2363
µmol/L for 0 or 20 mg/kg RAC, respectively,
P = 0·448) on Rmax.
However, the ED50 was significantly lower for
isoproterenol than for fenoterol (14·1 v.
31·3mg/kg, P = 0·001) and was
increased by dietary RAC (18·6 v 26·9
µg/kg, P = 0·05). In conclusion,
these data support the hypothesis that the lack of effect of dietary RAC on
the rate of lipid deposition in the pig is due to a desensitisation of adipose
tissue β-adrenergic receptors with no change in adipose tissue
responsiveness.
Rumen bacterial and protozoal populations in cattle being relocated in tropical Queensland
Authors: Klieve A. V. , Holroyd R. G. , Turner A. F. , Lindsay J. A.
Published: August 2004

Rumen microbial populations were measured in Brahman-cross steers that were
relocated from spear grass (Heteropogon contortus)
dominant pastures in northern Queensland to buffel grass
(Cenchrus ciliasis) dominant pastures in central
Queensland, to assess whether aspects of rumen function may contribute to the
sometimes reported depressed growth rates following relocation.
Nine genera of ciliate protozoa
(Isotricha, Dasytricha, Entodinia, Epidinium, Diplodinium, Ostracodinium, Metadinium, Elytroplastron, and Eudiplodinium)
were recorded in the rumen fluid of the steers. In most steers all genera were
present at any time and the generic mix persisted throughout the 10 months
over which the study was conducted. Protozoal population composition
fluctuated only slightly over the sampling period.
Entodinia were predominant, occupying 50-70% of
the population. Population density varied according to season, with the
highest density (4-8×105 /mL rumen fluid)
occurring in the wet season.
Bacterial and protozoal populations were remarkably stable and little affected
by relocation. Again, the major impact on population density was the season,
with all carbohydrate (soluble sugar, starch, xylan, and cellulose) utilising
bacterial subpopulations reaching the greatest density with the onset of the
wet season.
Evaluation of Angus, Charolais, and Hereford as terminal sire breeds on Hereford and first-cross cows. III. Meat quality of progeny
Authors: Hearnshaw H. , Arthur P. F. , Shorthose W. R. , Sinclair A. J. , Johnston D. , Stephenson P. D.
Published: August 2004

Carcasses of 435 Angus, Charolais, and Hereford sired progeny out of
straightbred Hereford (H × H), and first-cross Brahman × Hereford
(B × H), Simmental × Hereford (S × H) and Friesian ×
Hereford (F × H) dams, were evaluated for meat quality traits. The
cattle had been raised and slaughtered for the vealer (both sexes), yearling
domestic (both sexes), or the heavy export steer market. Meat samples from the
M. longissimus (LD, striploin) and the M. semitendinosis (ST, eyeround) were
evaluated for colour, cooking loss, sarcomere length, shear force parameters,
instron compression values, lipid content (LD only), cholesterol content (LD,
vealers only), and taste panel assessment (LD only). The effects of sire breed
and dam breed were small and were significant for only a few traits. The use
of either hot carcass weight or pH of meat as a covariate reduced the
differences further but did not change sire breed or dam breed rankings. Meat
from B × H progeny, which had 25%
Bos indicus (Brahman) breeding, was as tender as that
from progeny of the other dam breeds, which had no Bos indicus breeding.
Striploins from vealer carcasses were more tender and had less fat (mean peak
force, 3·8 kg; mean lipid in lean steak, 3·8 g/100 g) than
those from yearling domestic carcasses (mean peak force, 4·1 kg; mean
lipid in lean steak, 5· 0 g/100 g) which in turn were more tender
than those from heavy export steer carcasses (mean peak force, 4·9 kg;
mean lipid in lean steak, 6·3 g/100 g). From the total responses of
the taste panel, 65% rated vealer striploins of good or excellent
overall acceptability, compared with 29% for heavy export steer meat.
Trimming subcutaneous fat from striploin steaks of vealers reduced lipid
content and cholesterol content by 85% and 32% to 3·8
g/100 g and 55 mg/100 g, respectively.
Responses of faba bean (Vicia faba L.) to sowing rate in south-western Australia II Canopy development, radiation absorption and dry matter partitioning
Authors: Jettner R. , Loss S. P. , Martin L. D. , Siddique K. H. M.
Published: August 2004

Sowing rate influences plant density, canopy development, radiation
absorption, dry matter production and its partitioning, and seed yield. The
canopy development, radiation interception, and dry matter partitioning of
faba bean (cv. Fiord) were examined using 6 sowing rate treatments from 70 to
270 kg/ha in field experiments conducted over 3 years at Northam as part
of a larger investigation of sowing rate responses in faba bean in
south-western Australia.
High sowing rates resulted in significantly earlier canopy closure, larger
green area indexes, more radiation absorption, more dry matter accumulation
particularly during the early vegetative stages, and greater seed yield than
treatments where a low plant density was established. The results suggest that
further increases in canopy development, radiation absorption, dry matter
accumulation, and seed yield are possible by using sowing rates in excess of
270 kg/ha. The rate of node appearance was relatively constant within and
across seasons (1 every 65·9 degree-days), whereas the number of
branches per plant declined with increasing plant density, and less branches
survived through to maturity at high density. The peak photosynthetically
active radiation absorption (75-85%) measured at green area index of
2·9-3·8 in the highest sowing rate treatment in this study is
similar to previous reports for other crops. The estimated radiation use
efflciency (1·30 g/MJ) was constant across sowing rate treatments
and seasons. High sowing rates produced tall crops with the lowest pods
further from the soil surface than those at low plant density, and hence,
mechanical harvesting was easier. The growth of individual plants may have
been limited by the low growing season rainfall (266-441 mm) and/or low
soil pH (5·0 in CaCl2) at the site, and
competition between plants for radiation was probably small even at the
highest sowing rate. Early canopy closure and greater dry matter production
with high sowing rates may also cause greater suppression of weeds and aphids.
Adaptation of lentil (Lens culinaris Medik) to short season Mediterranean-type environments: response to sowing rates
Authors: Siddique K. H. M. , Loss S. P. , Regan K. L. , Pritchard D. L.
Published: August 2004

The growth and seed yield response of lentil (cv. Digger) to sowing rate
(20-120 kg/ha) was studied at 13 sites over 3 seasons in the cropping
regions of south-western Australia. The economic optimum plant density was
estimated by fitting an asymptotic model to the data and calculating the
sowing rate above which the cost for additional seed was equivalent to the
revenue that could be achieved from the extra seed yield produced, assuming a
10% opportunity cost.
On average across all sites and seasons, only 51% of sown seeds
emerged. Increasing sowing rate resulted in greater dry matter production at
˚owering and maturity, and fewer pods per plant. Harvest index
(0·31-0·36), number of seeds per pod (1·13-1·84),
and mean seed weight (2·9-3·6 g/100 seeds) remained
relatively stable with changes in sowing rate. The asymptotic models fitted to
seed yields accounted for 1-73% of the total variance in the data,
except at one site where a model could not be found to provide an adequate fit
to the data. In addition to this site, another 5 sites were excluded from
further consideration where the percentage of variance accounted for was
<25% or the predicted optimum densities and seed yield potentials
were well beyond the range of the data. The economic optimum of the remaining
7 sites ranged from 96 to 228 plants/m2, with a
mean of 146 plants/m2. These results suggest that
lentil yields may be improved by increasing sowing rates beyond those
currently targeted in southern Australia (100-125
plants/m2). On the basis of these results,
targeting a density of about 150 plants/m2 by using
a sowing rate of approximately 90-110 kg/ha is recommended, depending on
mean seed weight and germination percentage of the seed. Even higher sowing
rates may be optimum where the growing conditions are unfavourable and
individual plant growth is limited.
Micropropagated bananas are more susceptible to fusarium wilt than plants grown from conventional material
Authors: Whiley A. W. , Searle C. , Pegg K. G. , Smith M. K. , Langdon P. W. , Schaffer B.
Published: August 2004

The reaction of field-grown micropropagated bananas,
Musa cv. Williams (AAA, Cavendish subgroup) and cv.
Goldfinger (AAAB, FHIA-01), to subtropical race 4
Fusarium oxysporum f. sp. cubense
(Foc) was compared with the reaction of plants grown
from conventional planting material (sections of the rhizome, termed bits).
Leaf gas exchange of plants was determined, and growth and dry matter
accumulation were measured. Comparisons were made among these parameters from
shortly after planting, throughout winter, and into spring when a high
percentage of the plants started to show external symptoms of fusarium wilt.
Micropropagated bananas were significantly more susceptible to race 4
Foc than plants derived from bits. This was irrespective
of planting times, cultivars used, or whether the bits had first been
established in containers in the glasshouse (as for micropropagated plants) or
been planted directly in the field. This greater susceptibility does not
appear to be a consequence of differences in maximum photoassimilation rates,
greater photoassimilate demand, or lack of carbohydrate reserves once plants
became established.
Sorghum hybrid differences in grain yield and nitrogen concentration under low soil nitrogen availability. II. Hybrids with contrasting phenology
Authors: Kamoshita A. , Cooper M. , Muchow R. C. , Fukai S.
Published: August 2004

Genotypic variation for phenology is important when considering the adaptation
of grain sorghum (Sorghum bicolor (L.) Moench) to
adverse environments, but little is known about its role under environmental
conditions that result in low soil nitrogen (N) availability. We examined the
role of phenology in relation to other traits considered to contribute to the
adaptation of sorghum to low soil N conditions.
Four hybrids with contrasting maturity date were examined (2 early and 2 late)
under conditions of full irrigation supply. The late-maturing hybrids had
higher yield than one of the early hybrids only in optimum N conditions (960
v. 815 g/m2). The high yield
of the late-maturing hybrids was a result of greater biomass production due to
a longer period of radiation interception, rather than a greater fraction of
radiation interception at any time. Longer growth duration had no positive
effect on N capture, resulting in a lower grain N concentration at maturity
relative to the early-maturing hybrid (1·42%
v. 1·67%). The other early-maturing
hybrids achieved a comparable amount of biomass production and grain yield
(997 g/m2) to the late-maturing hybrids, and higher
grain N concentration (1·55%). This was attributed to their
higher plant N uptake by maturity, which contributed to higher grain N and
maintained higher radiation use efficiency (RUE) relative to the other
hybrids.
Under N-limiting conditions, the advantage of the late-maturing hybrids was
small in terms of radiation interception, and there was no advantage in terms
of total plant N content. One of the early-maturing hybrids continued to
absorb more N and accumulated larger amounts of N to grain for a longer period
after anthesis than the other hybrids, resulting in higher grain N
concentration (1·10% v.
0·92%). Genotypic variation for RUE, N utilisation, and harvest
index was observed, but was confounded with the other components, resulting in
a small difference in yield (392–454 g/m2).
Assessment of infection and sporulation processes of Puccinia menthae on peppermint in controlled conditions
Authors: Edwards J. , Parbery D. G. , Taylor P. A. , Halloran G. M.
Published: August 2004

The effects of environmental factors on components of the life cycle of
Puccinia menthae on
Mentha × piperita cv. Tod’s Mitcham were
examined. Urediniospore germination required at least 6 h leaf wetness and
lasted 4-6 h at temperatures of 5-25ºC. Appressoria, substomatal
vesicles, and haustoria were produced 6, 6, and 24 h after inoculation,
respectively, at 20ºC. The latent period of infection ranged from 50 days
at 5ºC to 10 days at 22ºC. Sporulation occurred over a wide range of
temperatures (5-27ºC), the optimum being 15-20ºC. The minimum,
optimum, and maximum temperatures for infection were <5, 20, and 27ºC,
respectively. Teliospore formation required a minimum of 9 days of cold
treatment (4ºC) and the ratio of teliospores to urediniospores produced
was inversely proportional to the duration and intensity of light received.
Population dynamics of Stylosanthes hamata and S. scabra in north-eastern Queensland: effects of superphosphate application, timber treatment, and stocking rate
Authors: McIvor John G. , Gardener Chris J.
Published: August 2004

The effects of pasture management (superphosphate application, timber
treatment, stocking rate) on the herbage yields and population dynamics (seed
production, seedling numbers, plant longevity) of
Stylosanthes hamata cv. Verano and
S. scabra cv. Seca grown in
grass-legume mixtures were measured from 1982 to 1992 at 2 sites, Hillgrove
(extractable phosphorus, 50 mg/kg) and Cardigan (extractable phosphorus, 6
mg/kg), near Charters Towers, north-eastern Queensland.
Stylosanthes hamata was higher yielding during the first
3 years at both sites but subsequently S. scabra produced the larger yields. This resulted in S. hamata dominating the legume
component in the early years but the proportion of S.
hamata then declined, so that by the final year,
S. hamata contributed
<20% of the legume mixture at both sites.
Both seed yields and seedling numbers varied widely between years for both
species at both sites. In the early years there were more
S. hamata seedlings but in the
later years S. scabra had greater
seedling numbers. Seed yield and seedling numbers were not significantly
affected by superphosphate but both were higher for S.
hamata on plots with live trees than on plots with
killed trees; numbers of seeds and seedlings of S.
scabra were not affected by tree killing. Seed and
seedling numbers of both species tended to be greatest at the intermediate
stocking rates. Survival of both S.
hamata and S. scabra at both sites conformed to Deevey"s Type II
curve (i.e. death rate was constant with age). The S.
scabra plants lived considerably longer than the
S. hamata plants. Pasture treatments had less influence
on longevity than on seed production and seedling numbers.
Seed production and seedling establishment of both species were marginal for
their persistence in the region, and management should aim for seed set and
subsequent seedling establishment to occur sufficiently frequently to allow
the legumes to persist.
A comparison of six methods to control take-all in wheat
Authors: Gardner P. A. , Angus J. F. , Wong P. T. W. , Pitson G. D.
Published: August 2004

Take-all is a root disease of wheat caused by the fungus
Gaeumannomyces graminis var.
tritici (Ggt). The most common method of control,
growing wheat after a break crop, is not always feasible. This study compared
the use of a break crop with 5 alternative control methods in a series of
field experiments in south-eastern Australia. The methods of control tested
were: (1) fungicide added to fertiliser;
(2) soil fumigation with methyl bromide;
(3) applied chloride; (4) seed
treatment with microbial antagonists; (5) a prior
brassica break crop; and (6) a 12-month-long fallow.
Eight experiments were conducted over 2 years but not all treatments were
included in each experiment.
The most successful control methods were growing wheat after a brassica break
crop or a long fallow. Both methods gave 72% yield increases over wheat
growing after wheat. None of the other methods gave consistent, significant,
or profitable yield increases or disease control. The mean yield increases in
the year of application were 8% for the fungicide, 6% for
microbial antagonists, 4% for chloride, and 7% for fumigation.
The probable reason that fungicide and microbial antagonists were ineffective
was that they were localised in the furrow where they were applied, whereas
roots became infected in the inter-row space. Probable reasons that chloride
was ineffective were that the background soil chloride levels were generally
above the responsive range, and that roots became infected with take-all after
the chloride was leached from the topsoil. The limitation of fumigation was
that it suppressed natural antagonists of the Ggt, apparently leading to
reinfection at higher levels than before. There was also evidence of Ggt
re-infection in the second year after break crops, leading to an apparent
‘boomerang’ effect.
Take-all inocula at the sites were measured in pre-sowing soil bioassays,
whereas disease incidence was determined in seedlings and as
‘whiteheads’ as crops approached maturity. The only consistent
pattern among the measurements was low disease incidence after break crops and
the long fallow. Otherwise, there were low correlations between the 3 sets of
measurements, suggesting that environmental changes after the soil bioassay
and seedling assessment played critical roles in the progress of the disease.
Comparison of shoot regeneration potential from seedling explants of Australian cauliflower (Brassica oleracea var. botrytis) varieties
Authors: Smith Nicole A. , Bhalla Prem L.
Published: August 2004

Genetic engineering of crop plants relies on the development of efficient
methods for the regeneration of viable shoots from cultured tissues. The
objective of the present study was to develop a protocol for efficient shoot
and plant regeneration from seedling explants of commercial cauliflower
(B. oleracea var. botrytis)
genotypes and to compare the regeneration capacity of the most commonly used
explants: cotyledon, hypocotyl, and root. A combination of growth hormones
including 6-benzylaminopurine, 1-naphthylacetic acid, and gibberellic acid was
used in the MS-based medium, and factors influencing regeneration of
shoots were investigated. Using the protocol described here, shoots from
hypocotyl, cotyledon, and root explants of all the 11 genotypes tested were
able to be regenerated. Root and hypocotyl explants produced more callus than
cotyledon explants and also were more responsive to shoot regeneration, as a
high percentage (>71% and >80% for hypocotyl and roots,
respectively) of shoot initiation from these explants was observed. In
addition, root and hypocotyl explants also produced more shoots per explant
than cotyledon explants. The in vitro regenerated shoots were successfully
rooted and acclimatised to glasshouse conditions. This study shows that
seedling explants of cauliflower are amenable to multiple shoot formation with
high regeneration frequencies, and could be used for genetic transformation
experiments.
Changes in Floristic Composition of Urban Bushland Invaded by Pittosporum undulatum in Northern Sydney, Australia
Authors: Rose Stefan , Fairweather Peter G.
Published: August 2004

Differences in species composition of urban bushland sites that had been
subjected to increasing degradation and progressive invasion of
Pittosporum undulatum Vent. were assessed using
nonparametric multivariate and other statistical techniques. Increasing suburb
age was found to significantly affect community pattern as a whole,
specifically through increased proportions of exotic species, decreased native
species richness and sustained shifts in the relative importance of individual
species. Older suburbs were typified by species that were mesic,
fire-sensitive, shade-tolerant and adapted to relatively moist, nutrient-rich
edaphic conditions. These species included P. undulatum
and many invasive exotics. Many native species decreased substantially in rank
importance with increasing suburb age, to the point of elimination in older
suburbs. These included one vulnerable taxon
(Tetratheca glandulosa Sm.). Overall community pattern
was correlated with abundance of P. undulatum, fire and
human disturbance. Relative cover of P. undulatum was
found to be significantly correlated with increased proportions of exotic
species and reduced native species richness and diversity. While most exotic
species were concentrated within 30 m of the suburban edge, it is suggested
that most management effort should be directed at those exotic species that
commonly establish throughout bushland remnants. The study also provided an
opportunity to test the application of the multivariate software package
PRIMER in assessing environmental impact on vegetation communities.
Distribution, Disturbance Tolerance and Conservation of Stackhousia gunnii in Tasmania
Authors: Kirkpatrick J. B. , Gilfedder L.
Published: August 2004

Although being possibly widespread on the mainland of Australia, where it is
recognised as part of the Stackhousia monogyna Labill.
complex, S. gunnii Hook.f. is an endangered species in
Tasmania, with only 10 known extant populations, all in the drier parts of the
southern Midlands. These populations occur largely on roadsides or lightly
grazed paddocks in vegetation that was originally either
Themeda triandra grassland or
Eucalyptus pauciflora woodland. An ordination of
floristic data from sites with and without S. gunnii
showed that the species occupies a floristically distinct environment. The
floristic differences between stands of S. gunnii relate
partly to the presence or absence of tree cover and substantially to
precipitation. The groups of species that preferentially occur with
S. gunnii are geophytes, non-geophytic herbs and exotic
plants, while those that are concentrated elsewhere include shrubs, grasses
and non-geophytic graminoids. Permanent transects were monitored over a 4-year
period at seven sites with varying grazing, firing and disturbance. The number
of shoots varied markedly between years in all sites, but not synchronously,
even when transects were in close proximity. Although shoot numbers increased
after fires occurred on several ungrazed transect lines, they decreased on one
grazed line. Deep mechanical disturbance of one site resulted in a dramatic
decrease in shoot numbers in the following year. However, they increased
steadily over the following 2 years. Shoot emergence occurred at twice the
expected rate on bare ground in all years and at all sites, and a substantial
proportion of shoots was confined to this type of surface. However, shoots
were also recorded in fewer numbers in grass cover, herb cover and
non-vascular plant crusts. Like some other threatened plants of grassy
ecosystems, S. gunnii seems to be rare because it cannot
survive with heavy grazing disturbance, ploughing and fertilisation, and, at
the other extreme, because it is susceptible to elimination in the absence of
environmental conditions and disturbances that create bare ground.
Long-term Variation of Litter Fall, Canopy Leaf Area and Flowering in a Eucalyptus maculata Forest on the South Coast of New South Wales
Authors: Pook E. W. , Gill A. M. , Moore P. H. R.
Published: August 2004

Litter fall, canopy leaf area and environmental conditions were monitored in a
regrowth stand of Eucalyptus maculata Hook. in Kioloa
State Forest on the south coast of New South Wales, from spring 1977 to winter
1992. Litter fall during the first half of the study period was strongly
influenced by two of the most serious droughts that had occurred in 100 years.
Canopy renewal and, hence, leaf fall and changes of leaf area index (LAI),
were also influenced by the flowering phenology of
E. maculata. Total annual litter fall (including bark
shed from lower boles) averaged 5.7 t ha-1 and ranged
from 3.1 up to 7.5 t ha-1. The respective means (plus
absolute ranges) of annual leaf, twig and bark fall were 2.8 (1.5–4.2),
0.9 (0.3–1.4) and 1.6 (0.5–3.1) t ha-1.
Forest LAI varied between 0.7 and 5 m2
m-2. Leaves comprised 50% of the average annual
litter fall; bark shed from lower boles of E. maculata
contributed 0.63 t ha-1 to average annual bark fall.
Flower buds were produced by a proportion of overstorey trees of
E. maculata about every second year. Synchronous
production and flowering of buds on all trees was observed only once in 15
years. Less than 15% of flower buds (overall) produced fruit.
Vegetation Patterns, Environmental Correlates and Vegetation Change in a Puffinus tenuirostris Breeding Colony at Cape Queen Elizabeth, Tasmania
Authors: Walsh D. , Kirkpatrick J. B. , Skira I. J.
Published: August 2004

Variation in the vegetation in and adjacent to a
Puffinus tenuirostris breeding colony at Cape Queen
Elizabeth, Bruny Island, Tasmania is related much more closely to burrow
density, bare ground and soil dryness than to either the phosphorus or organic
content of the soils. Between 1977 and 1992, burrow density declined on
average by 0.11 per m2. In the parts of the rookery
where burrow density decreased, Rhagodia candolleana
Moq. increased its cover. Where burrow density remained constant or increased,
Pteridium esculentum (G.Forster) Cockayne and
Lomandra longifolia Labill. had declining cover. The
major overall changes were increases in the cover of the succulent scramblers
Tetragonia implexicoma (Miq.)J.D.Hook and
Rhagodia candolleana at the expense of
Pteridium esculentum and
Lomandra longifolia.
Water Balance of an Australian Subtropical Rainforest at Altitude: the Ecological and Physiological Significance of Intercepted Cloud and Fog
Authors: Hutley Lindsay B. , Doley David , Yates David J. , Boonsaner Arthorn
Published: August 2004

A water balance study of a small subtropical rainforest catchment (10 ha, 1000
m altitude) was conducted at Gambubal State Forest, near the headwaters of the
Condamine River, 200 km south-west of Brisbane, south-eastern Queensland. Mean
annual rainfall of the site is approximately 1125 mm, but is variable and
often less than 900 mm. Tree transpiration rates are low and depletion of the
large soil moisture reserves enables extraction for lengthy periods of time,
permitting survival during extended dry seasons (May–November). Fog
deposition to the forest provides the equivalent of an additional 40%
of rainfall to the site as measured using a conventional rain gauge. A
frequently wet canopy results in reduced transpiration rates and direct foliar
absorption of moisture alleviates water deficits of the upper crown leaves and
branches during the dry season. These features of this vegetation type may
enable long-term survival at what could be considered to be a marginal
rainforest site.
Diurnal and Seasonal Comparisons of Assimilation, Phyllode Conductance and Water Potential of Three Acacia and One Eucalyptus Species in the Wet - Dry Tropics of Australia
Authors: Eamus D. , Cole S.
Published: August 2004

Four species of tropical tree (Acacia auriculiformis
Cunn. ex Benth., A. mangium Willd.,
A. crassicarpa Cunn. ex Benth. and
Eucalyptus pellita F.Muell.) were studied at a site on
Melville Island, off the north coast of the Northern Territory of Australia,
in the wet–dry tropics. Rates of light-saturated assimilation were
measured every 2 months, in the morning and afternoon, concurrently with
gs (stomatal conductance) and
microclimate (air temperature, relative humidity and photosynthetic photon
flux density). Phyllodes were also sampled for subsequent nitrogen
determination. Pre-dawn and diurnal phyllode water potentials were measured at
the end of the wet and dry seasons. Tree height and canopy area were recorded
at the end of 50 months of growth. Assimilation was found to decline
substantially in the afternoon compared with the morning in the dry season but
not the wet season. This was not due to diurnal declines in phyllode water
potential but was attributed partially to decreased
gs resulting from increased
leaf-to-air vapour pressure difference. However, an interpretation of the
Ci/Ca
(ratio of intenal to ambient CO2 concentrations) data
suggested that additional factors, other than
gs, may be involved in causing the
afternoon decline in assimilation rate. There was a linear relationship
between pre-dawn water potential and
Amax (maximum assimilation) and an
inverse relationship between Amax
and tree height, a result attributed to differences between species in
allocation of carbon within the tree.
Estimation of Eucalypt Forest Leaf Area Index on the South Coast of New South Wales using Landsat MSS Data
Authors: Coops Nicholas , Delahaye Antoine , Pook Eddy
Published: August 2004

Research over the last decade has shown that regional estimation of Leaf Area
Index (LAI) is possible using the ratio of red and near infrared radiation
derived from satellite or airborne sensors. At landscape levels, however, this
relationship has been more difficult to establish due to (i) logistic
difficulties in measuring seasonal variation in LAI across the landscape over
an extended period of time and (ii) difficulties in establishing the effect of
understorey, canopy closure, and soil on the spectral radiation at fine
spatial resolutions (< 100 m). This paper examines the first issue by
utilising a temporal sequence of LAI data of a
Eucalyptus mixed hardwood forest
(E. maculata Hook., E. paniculata
Sm., E. globoidea Blakely,
E. pilularis Sm., E. sieberi
L.Johnson) in south-eastern New South Wales and comparing it to historical
Landsat Multi-Spectral Scanner (MSS) data covering a 9 year period. Field LAI
was compared to the Normalised Difference Vegetation Index (NDVI) and the
Simple Ratio (SR) derived from the MSS data. Linear relationships were shown
to be appropriate to relate both transformations to the LAI data with
r2 -values of 0.71 and 0.53
respectively. Using the NDVI relationship, LAI values were estimated along a
transect originating from the monitoring site and these were compared to
percentage canopy cover values derived from aerial photography.
The Nutritional Status of Healthy and Declining Stands of Banksia integrifolia on the Yanakie Isthmus, Victoria
Authors: Bennett L. T. , Attiwill P. M.
Published: August 2004

Banksia integrifolia L.f. has been in decline on
calcareous sands of the Yanakie Isthmus, southern Victoria, since early 1980.
Early studies indicated that the decline is associated with a particular soil
condition possibly a nutritional imbalance involving Fe. However, in foliage
samples collected from the three main soil types of the Isthmus, declining
trees had similar concentrations of Fe but lower concentrations of Ca than
healthy trees. Comparisons were made of seasonal variation in concentrations
of macro- and micro-nutrients in foliage and litterfall from healthy trees (to
minimise secondary changes associated with decline) within healthy and
declining sites on the same soil type. On average, litterfall and the nutrient
content of litterfall was greatest within the canopy area of
B. integrifolia of the healthy stand. Banksias of the
healthy stand also had greater concentrations of N, P, K and Na in
fully-expanded leaves, resorbed greater proportions of phloem-mobile nutrients
from senescent leaves and accumulated more Ca in senescent leaves. However,
there was no evidence of nutritional imbalance in healthy trees within
declining stands. It is argued that the lower foliar Ca in declining trees on
three soil types and lower nutritional status of healthy trees within
declining stands were due to lower productivity and lower water use and were
therefore a result or an indication of decline rather than a cause.
Self-incompatibility, Seed Abortion and Clonality in the Breeding Systems of Several Western Australian Drosera species (Droseraceae)
Authors: Stace Helen M. , Chen Lin , James Sidney H.
Published: August 2004

Western Australian Drosera L. species include one annualand many tuberous and pygmy perennials. In 20 species or subspecies, 17 taxawere self-incompatible (SI) and three were self-compatible (SC), as assessedby patterns of seed set and pollen tube growth. All SI species were clonal(tubers or gemmae), but two SC species were clonal (gemmae) and one wasannual. Self-pollen tube inhibition confirmed that SI species werepre-zygotically self-sterile. The sites of SI pollen tube inhibition variedfrom early (stigmatic) to late (stylar, placental, ovular), which suggestscontinuing evolution in the expression of the SI response. Self-compatiblespecies showed little inbreeding depression, but SI species showedconsiderable inbreeding depression as measured by seed abortion. In the threespecies tested, open-pollinated capsules were typically more fecund thanhand-pollinated capsules. In D. glanduligera Lehm., thismight represent position effects in an inflorescence that were reflected inthe sampling method. In other species, however, this might also reflectbiparental inbreeding depression in the glasshouse plants. Interspecificcrosses between D. tubaestylis N.Marchant & A.Lowrie(n = 14) and D. rosulataLehm. (n = 13) were slightly successful, with nopollen–pistil incompatibility interaction, but with extensive seedabortion. This is the first report of SI in Droseraceae.
Palaeoclimate across an Altitudinal Gradient in the Oligocene - Miocene of Northern Tasmania: an Investigation of Nearest Living Relative Analysis
Authors: Scriven Leonie J. , Hill Robert S.
Published: August 2004

An examination of the nearest living relatives (NLRs) of macrofossil taxa that
occur in at least two of five Oligocene–Miocene fossil sites in northern
Tasmania indicates that those with mesothermal affinities are restricted to
the low altitude sites. Since this occurs over a wide range of taxa, it is
clear support for the hypothesis that an altitudinal temperature gradient
occurred during the Oligocene–Miocene in Tasmania. Among the high
diversity of Dacrycarpus macrofossils present in the
deposits, there is morphological evidence that the species found at the
highest altitude site (Monpeelyata) grew in a climate
that is outside the range encompassed by extant species, suggesting that there
has been selective extinction within this genus, resulting in a narrowing of
the climatic range in which it occurs today. Two subgenera of
Nothofagus Blume (Lophozonia
(Turcz.) Krasser and Nothofagus) show a trend in leaf
size among Cenozoic localities in Tasmania, but the rate of change apparently
varies between the two. In both cases the trend is towards smaller leaves in
higher altitude and/or more recent (i.e. cooler) deposits. Nearest living
relative analysis is shown to be an extremely valuable technique in
palaeoclimate reconstruction if it is applied in sufficient detail, although
at present it is best applied qualitatively.
A Bioclimatic Analysis of Early to Middle Miocene Brown Coal Floras, Latrobe Valley, South-eastern Australia
Authors: Kershaw A. P.
Published: August 2004

The bioclimatic prediction system BIOCLIM is employed to provide an estimate
of Early to Middle Miocene climate from the overlapping present-day climatic
parameter ranges of selected taxa recorded in the Latrobe Valley coal seams.
Despite taxon identification to only a coarse taxonomic level, fairly tight
climatic envelopes are derived, particularly for temperature parameters. The
data suggest that mean annual temperatures may have been about 5˚C higher
than those of today, with a similar seasonal temperature variation. Minimum
annual precipitation is estimated to have been at least 1500 mm and probably
much higher, compared to the present average of 800 mm, with most of the
additional rainfall falling in the wet season. By comparison with previous,
more qualitative, estimates, the degree of seasonal variation is surprising,
but may be accounted for by the high latitudinal position of southern
Australia during the period of coal formation. A number of factors including
the degree to which the distribution of rainforest taxa in the present day may
reflect their climatic potential, the possibility of ecological change within
recognisable taxa, and the influence of a swamp environment on taxon
distributions, all of which may limit the accuracy or validity of these
estimates, are examined. It is concluded that the estimates are realistic in
broad terms, but can only apply to the limited periods of high sea level,
which allowed accumulation of the swamp precursors of the brown coals.
The Use of Ecological Tolerances for the Reconstruction of Tertiary Palaeoclimates
Authors: Martin Helene A.
Published: August 2004

The major vegetation types may be recognised from the pollen assemblage being
deposited beneath them, hence the palaeovegetation may be reconstructed from
fossil pollen assemblages. The climatic parameters of the vegetation may then
be used to reconstruct palaeoclimates. The result, however, is very general.
Most pollen types can only be affiliated with a family, a genus or a group of
species and the ecological tolerances within these groups may not be uniform.
There are, however, some distinctive pollen types that can be identified with
a single living species and this paper examines the potential of these types
in the reconstruction of palaeoclimates.
Lagarostrobos franklinii (J.D.Hook) Quinn, Huon pine,
has a long history and the fossil occurrences of it are compatible with the
hypothesis that its ecological tolerances have not changed and it has always
required very high humidity. Two sclerophyllous
taxa,Eucalyptus spathulata Hook. and
Dodonaea triquetra Wendl., however, coexisted with
rainforest and then other vegetation types as the climate became drier,
adapting to the prevailing conditions. The evidence suggests that the
salt-tolerant E. spathulata may have evolved in small
patches of coastal scrub, subjected to marine influence, within the dominant
rainforest vegetation.
Contrasts between the Climatic Ranges of Fossil and Extant Taxa: Causes and Consequences for Palaeoclimatic Estimates
Authors: Jordan Gregory J.
Published: August 2004

Many palaeoclimate estimates are based on the climatic ranges of the nearest
living relatives (NLRs) of fossils. If the climatic ranges of the true NLRs of
the taxa in a fossil assemblage do not overlap, then the past climatic ranges
of some of the fossil taxa are different from the ranges of their NLRs.
Discrepancies between the climatic ranges of the inferred NLRs of co-occurring
fossils are common, particularly in assemblages older than the Middle
Pleistocene. Evidence from Early Pleistocene Tasmania indicates that many
anomalies are caused by extinct species, or at least extinct genotypes. It is
likely that pre-Quaternary fossil deposits will contain more extinct taxa.
Most of the extinct Early Pleistocene taxa have warm climate NLRs, but they
appear to have occurred in climates no warmer than modern climates in western
Tasmania. Sometimes NLR approaches in climate reconstruction appear to be
biased by extinctions of ecotypes and species, especially ones caused by the
Pleistocene glacial–interglacial cycles. Extinctions also mean that it
is difficult to identify palaeoclimates that are different from any modern
climate.
Distribution of C3 and C4 Plants in the Late Pleistocene of South Australia Recorded by Isotope Biogeochemistry of Collagen in Megafauna
Authors: Gröcke Darren R.
Published: August 2004

Stable carbon-isotope analyses (expressed as a
13C:12C ratio relative to that of
a standard: δ13C) on fossilised collagenic
material in megafaunal bones can provide information regarding the palaeodiet
(e.g. C3 and/or C4 plants) of
these animals. Isotope analyses were performed on collagenic material
extracted from bones of Sthenurus spp.,
Diprotodon spp. and Macropus spp.
from Cooper Creek, Henschke Cave, Baldina Creek, Dempsey’s Lake and
Rocky River in South Australia. The percentage of trees and shrubs estimated
from palaeofloral records in south-eastern Australia and the dietary
preferences of megafauna were found to be positively correlated. The dietary
preferences of megafauna analysed from South Australian localities indicate
that megafauna were opportunistic and changed their diet in response to
environmental change. This suggests that megafauna diet can not be founded on
dental morphology alone. Fossilised collagenic material in vertebrate remains
can provide an insight into the broadscale nature of the vegetation. This
approach is a good compliment for other palaeoecological data (e.g.
sedimentology, spore–pollen, diatoms) by providing evidence for past
climates in relation to the proportion of C3 and
C4 plants.
Cytoevolution of Taxa in Acacia and Prosopis (Mimosaceae)
Authors: Bukhari Yahya M.
Published: August 2004

Somatic chromosome numbers were reported for 47 accessions of
Acacia (Tourn.) Miller, representing 23 species
including A. albida (syn.
Faidherbia albida), together with 19 accessions (11
species) of Prosopis (L.) Burkart. Microphotographs of
somatic metaphases of 12 accessions and six representative idiograms are
shown. Somatic numbers of different accessions of a species can be different.
Somatic numbers of accessions of subgenus Acacia were
predominantly 52; a few had 2n = 78 or 104.
However, A. sieberana had 2n
= 26 and A. nubica 2n
= 56. Except for A. polycantha, which had
2n = 52, somatic numbers of subgenus
Aculeiferum were invariably 26. Of the six species of
subgenus Heterophyllum studied, five had 26 somatic
chromosomes and one (A. holoceraceae) had 52. All the
four accessions of A. albida had
2n = 26. Out of the 19
Prosopis accessions investigated, five had 56 somatic
chromosomes and 14 accessions had 28. In Acacia,
subgeneric and specific differentiations are probably caused by structural
changes in the chromosomes, whereas differences in the degree of euploidy
appear to create infraspecies. Subgenus Aculeiferum is a
possible progenitor of all other taxa of Acacia and
Prosopis. The study suggests that
Prosopis has diverged later in geological times from a
diploid ancestor (2n = 26) of
Aculeiferum through centric fission of the
second-largest chromosome pair.
Distribution of Grass Species and Attributes of Grasses Near a Bore Drain in a Grazed Semi-arid Subtropical Grassland
Authors: Rogers R. W. , Stride C.
Published: August 2004

The distribution of grass species and a selection of attributes of those
species were related to distance from water in an otherwise natural,
sheep-grazed, semi-arid, subtropical grassland at Glencoban Station near
Cunnamulla in south-western Queensland, Australia. Twenty common species could
be classified as decreaser, increaser or neutral with respect to stocking
pressure based on distribution patterns with respect to distance from water.
No species known to be introduced to Australia were present. The occurrence of
a diversity of vegetative and diaspore attributes and carbon assimilation
pathways were also shown to be related to stocking pressure. The attributes
studied showed autocorrelation in two groups, which related to the higher
level taxonomy of the grasses and to response to stocking. Chloridoid grasses
increase and andropogonoid grasses decrease under high stocking pressure. In
this grassland, which has no introduced species, a syndrome of
stocking-related attributes can be discerned.
Allometric Relationships for Estimating Biomass in Multi-stemmed Mangrove Trees
Authors: Clough B. F. , Dixon P. , Dalhaus O.
Published: August 2004

A procedure is described for obtaining allometric relationships between stem
diameter and above-ground biomass for multi-stemmed trees of the mangroves
Rhizophora stylosa and
Avicennia marina. The procedure treats each stem as
discrete tree that shares a proportion of the butt and other elements common
to all stems. Linear log–log relationships were obtained between stem
diameter and the dry weights of each above-ground component. Allometric
relationships between stem diameter and total above-ground biomass were
similar to those for single-stemmed trees in north-eastern Australia, but
multi-stemmed trees on the west coast had much greater proportion of their
biomass in the form of prop roots than single-stemmed trees of comparable stem
diameter on the north-eastern coast. This is attributed to the arid
environment on the north-western coast of Australia.