bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of inorganic matrices on the decomposition of Eucalyptus litter
Authors: Skene T. M. , Skjemstad J. O. , Oades J. M. , Clarke P. J.
Published: August 2004

The decomposition of Eucalyptus litter (EL) in the
presence and absence of inorganic matrices [sand (S), sand+kaolin
(S+K), loamy sand (LS)] with and without added N (urea) was followed
over 48 weeks using chemical and spectroscopic means. At the end of the
incubation, the residual organic matter in different density and particle size
fractions was examined. Urea addition inhibited the mineralisation of C from
the litter in all treatments except EL+S+N, whereas the inorganic
matrices had little influence on mineralisation. Solid state
13C CP/MAS NMR spectra of the whole samples
suggested there were no differences in the degree of decomposition (as
determined by the O-alkyl-C : alkyl-C ratio) between the different treatments,
despite significant differences in the amount of C mineralised.
Inorganic matrices and N addition had a significant influence on the yields of
the 2 `light" fractions [D <
1·6 and 1·6 < D < 2·0, where
D (Mg/m3) is density].
There were also differences in the degree of decomposition (as determined by
the O-alkyl-C : alkyl-C ratio) of the D < 1·6
fractions from the different inorganic matrix treatments. However, there were
no differences in the degree of decomposition of the 1·6 <
D < 2·0 fractions. The C: N ratios and
O-alkyl- C: alkyl-C ratios of the different fractions revealed that the order
of fractions from the least decomposed to the most decomposed was
(D < 1·6) < (1·6 <
D < 2·0) < clay+silt < clay.
The NMR spectra of the whole samples suggest that a reaction between
aromatic-C and urea occurred during the first week of the incubation which may
have rendered the N unavailable to microorganisms. This reaction requires
further investigation.
The results were quite different from a similar study on the decomposition of
straw. These differences suggest that, for high quality substrates, physical
protection by inorganic matrices is the limiting factor to decomposition,
whereas for low quality substrates, chemical protection is the limiting
factor.
Use of natural heterogeneity in a small field site to explore the influence of the soil matrix on nitrogen mineralisation and nitrification
Authors: Strong D. T. , Sale P. W. G. , Helyar K. R.
Published: August 2004

The influence of soil properties on microbiological processes is often
examined by comparing the behaviour of taxonomically disparate soils. One of
the limitations of this approach is that the results can be confounded by the
unmeasured properties which vary between soils of different type or between
soils which have had different climatic and management histories. This study
tested the hypothesis that the heterogeneity between 100 small contiguous
undisturbed soil cubes (about 1·7 cm3), sampled
from the surface of a very small field plot (14 by 14 cm), was sufficiently
large to use for the exploration of how soil properties influence biological
processes. After incubation of the soil for 35 days, the coefficients of
variation for nitrate (NO3), ammonium
(NH4), gravimetric water content
(θg), bulk density (BD), pH buffering capacity
(pHBC), and pH were 28, 39, 27, 10, 13, and 2%, respectively. A
multiple regression equation predicting nitrate concentration had an
r2 value of 0·89 and
significantly included 4 predictor variables, with only pH being
non-significant. These analyses confirmed the hypothesis.
When the values of measured soil properties of adjoining soil cubes were
meaned to estimate values for larger soil volumes, the multiple regression
equations for predicting NO3 concentration explained
more of the variation (r2 values
as high as 0·99). However, information concerning the influence of
certain soil properties on N mineralisation and nitrification was lost, with
only pHBC and BD remaining significant in the regression model. It was
concluded that at a given physical scale of investigation, the structure of
the spatial variability may determine whether or not a relationship between 2
variables is observed. Smaller samples are more likely to identify functional
relationships which may exist between measured variables at the microscale.
Reactive Fe controls the relative amount of PO4 extracted from acidic soils by NaHCO3 and by acidic fluoride I. Soils without recent P additions
Authors: Vimpany I. A. , Nicholls P. J. , Milham P. J. , Bradley J.
Published: August 2004

The relations of reactive Fe and Al fractions (oxalate-extractable) with 2
measures of extractable orthophosphate (Colwell and Bray-1) were examined for
47 acidic, mineral, surface soils from eastern New South Wales. The soils had
developed from 3 different parent materials and had a wide range of chemical
compositions; most would have been P-deficient in their virgin state. Some of
the soils had received P fertiliser to promote pasture growth but none had
been fertilised with P for at least 2 years before sampling. Variation among
soils in the log of the ratio of values for the P tests (Colwell/Bray-1)
was related to the log of the concentration of either oxalate Fe
(R2 = 0 · 87) or
oxalate Al (r2 = 0 ·
24), or P sorption (r2 = 0
· 26). Soil parent material had no significant effect on these
relations. Two independent data sets support the strong relation of log
(Colwell/Bray-1) with log(oxalate Fe); however, not all of the relations
are identical and possible reasons for the differences are discussed. The
complete set of relations indicates that under the described conditions, much
of the orthophosphate may be bound to reactive Fe. It is inferred that across
a set of acidic, mineral soils that have not had recent additions of P and
which vary widely in Feox, the critical levels of the
Colwell test should vary over a much wider range than the corresponding Bray-1
values. Consequently, for the Colwell test to provide as reliable a guide to P
responses as the Bray-1 test, the Colwell test should be used in conjunction
with a measure of reactive Fe, such as oxalate-extractable Fe.
Flow systems, tree plantations, and salinisation in a Western Australian catchment
Authors: Stolte W. J. , McFarlane D. J. , George R. J.
Published: August 2004

A lower hillslope in the Western Australian wheatbelt had become waterlogged
and saline by 1981, when close-spaced rows of eucalypts were planted in blocks
both in and adjacent to the discharge area and piezometers were established on
the site. We analysed the trends in the piezometric heads and salinity
concentrations over the period of record. We also modelled the hillslope
profile using finite element analysis to determine the water flow mechanisms
and to see how a change in vegetation in the upland area would affect the
waterlogging and salinity.
Piezometric levels under the trees decreased for the first 5 years after
planting and then stabilised until 1991 when they started gradually decreasing
again. The non-treed area between the plantation blocks remained unaffected
until about 1991, when the levels there also started to decrease quite
significantly, probably because of the trees. The trees therefore appear to
have been effective and beneficial in the short to medium term.
However, the salinity of the groundwater under the trees has increased
significantly in the last 5 years, particularly where the tree density is
highest. The continued flow of saline groundwater to the trees is believed to
be increasing the salinity. It could not be expected that plantations of this
type will maintain health and be able to control the excess water in such an
hydrologic setting in the long term.
Tree plantations on discharge areas are a short to medium term management
strategy, not a solution, and the only way to control salinity in the long
term is to plant vegetation species in the recharge areas that use all of the
water that falls there. Modelling showed that only a small surplus of water
over winter, in the order of 50 mm/year, caused the increased recharge and
consequent salinisation. The modelling results also show that the surplus
could be managed with an effective vegetation species (e.g. lucerne) with a
rooting depth of about 1·5 m that would be able to transpire at least
until early to mid summer.
Ion exchange resin and MINTEQA2 speciation of Zn and Cu in alkaline sodic and acidic soil extracts
Authors: Fotovat Amir , Naidu Ravendra
Published: August 2004

The bioavailability of trace metals, their accumulation by organisms, and
their toxicity to terrestrial and aquatic organisms can be understood better
in terms of trace metal species. Although there are numerous chemical
techniques used for the determination of ionic species, most are tedious,
time-consuming, and not practical for routine analyses. Alternatives to these
chemical techniques are computer speciation models that often have an
incomplete database on metal–organic chemistry, yet scientists continue
to use these techniques for estimation of trace metal activities. In this
study we compare the cation exchange resin (Amberlite) and the MINTEQA2
geochemical model for the speciation of zinc (Zn2+)
and copper (Cu2+) in the aqueous phase of 11 soils
varying widely in chemical composition. The pHw(1:5) of
these soils ranged from 5·3 to 9·1, while the total soil aqueous
phase concentrations of Zn and Cu were in the ranges 1–71 and 5–74
µg/L, respectively. Preliminary equilibration studies revealed that
24-h contact between resin and sample solution was sucient to exchange all
free ions onto the resin bead. By using this equilibration time, the effects
of temperature, solution composition, and pH on the resin distribution
coeficients (Kd) for Zn and Cu
were investigated. These studies revealed that temperature did not
significantly influence the Zn and Cu resin distribution coecient. Solution
composition such as the presence of Ca, Mg, and Al, however, had a marked
effect on the Kd value. Although
the Kd value was not sensitive to
changes in solution pH (4·5–7·1), it increased at pH
>7·1. These results suggest that soil solution composition must be
considered during metal ion speciation using the resin beads. Changes in Zn
and Cu concentrations, however, did not influence the
Kd values of these metals. The
cation exchange resin method was modified for speciation of solutions
containing very low concentration (<50 µg/L) of Zn. Comparison of
the 2 speciation techniques demonstrated excellent agreement for free hydrated
Zn2+ and Cu2+ in the
soils studied.
Effects of repeated application on persistence and downward movement of four herbicides in soil
Authors: Ismail B. S. , Kalithasan K.
Published: August 2004

The downward movement and persistence of picloram, terbuthylazine, alachlor,
and pendimethalin were studied under tropical field conditions in loamy soil.
Picloram and alachlor were applied separately at 0·5 and 2·0 kg
a.i./ha, respectively, while terbuthylazine and pendimethalin were each
applied at 1 · 0 kg a.i./ha. Each herbicide was subjected to 2
experimental conditions: (i) the required amount of
herbicide applied 2 times, and (ii) the required amount
applied 6 times. The presence of these herbicides in soil was assessed by
bioassay techniques. Rice seed (Oryza sativa) and long
bean (Vigna sinensis) were used to assay pendimethalin
and picloram, respectively, while cucumber
(Cucumis sativus) was used for both alachlor and
terbuthylazine. The results showed that both alachlor and picloram moved
downward faster than terbuthylazine and pendimethalin. Both alachlor and
picloram, but not terbuthylazine or pendimethalin, could be detected in
5–10 cm layer at 1 day after application (DAA). The phytotoxic residues
of picloram, pendimethalin, terbuthylazine, and alachlor were detected in the
0–5 cm layer until 84, 56, 49, and 35 DAA (2 applications),
respectively. However, after 6 applications, the phytotoxic residue of these
herbicides in the top layer was reduced. Our results show that pendimethalin
was less mobile than the other herbicides. The half-lives of picloram,
pendimethalin, terbuthylazine, and alachlor were 9·7, 6·4,
6·0, and 4·4 days, respectively, after 2 applications, but after
6 applications, the half-lives of these herbicides were shorter.
Computer modelling of the effect of revegetation strategies on salinity in the western wheatbelt of Western Australia 1. The impact of revegetation strategies
Authors: Clarke C. J. , Mauger G. W. , Bell R. W. , CSIRO R. J. Hobbs
Published: August 2004

The interactions between land, vegetation, and climate are highly complex and
there are few demonstrations of the many potential combinations of treatments
which could be used to combat dryland salinity. For this reason, computer
simulations are used. This is the first of 2 papers that describe the results
of computer modelling of revegetation strategies to reduce land and water
salinisation in the western wheatbelt of Western Australia. A distributed
parameter, physically based, cellular, 2-layer, mathematical model was used to
simulate the effect of a variety of treatments. Modelling predicted that if
current land use continues, 40% of the cleared area will become saline.
Modelling replacement of the annual pasture with a deep-rooted perennial
pasture or pristine native vegetation prevented the onset of salinity, but
block or alley treatments always left a significant residual saline area and
seepage even at the highest density of revegetation modelled. Combining
remnant vegetation in pristine condition, 60-m-spaced tree belts and
deep-rooted perennial pasture in mainly the upper mid-slope bays between tree
belts reduced saline land to 10% of the cleared area and seepage volume
to 30% of the untreated case. The second paper describes the impact of
faults on treatment effectiveness.
Runoff and micromorphological properties of a grazed haplargid, near Cobar, NSW, Australia
Authors: Greene R. S. B. , Nettleton W. D. , Chartres C. J. , Leys J. F. , Cunningham R. B.
Published: August 2004

We investigated the effects of 2 different grazing regimes on the surface soil
properties of a dunefield land system in the semi-arid woodlands of eastern
Australia. Sandy siliceous, thermic Xeric Haplargids (Siliceous Sands,
Uc1·23) occur on the sandy, 2–4-m-high longitudinal dunes.
Fine-loamy, siliceous, thermic Xeric Haplargids (Massive Red Earths,
Uc2·13) occur in the swales between the dunes. We compared very
high-intensity grazing (approx. 1 year) by feral goats with low-intensity
grazing (approx. 4 years) by sheep. A rainfall simulator, applying water at
the rate of 30 mm/h, measured the hydraulic properties of the surface
soils formed under the 2 different grazing regimes. We examined undisturbed
samples of the upper 5-cm layer of the soil surface using micromorphological
techniques.
In the swales, there were no differences in the effects of the 2 grazing
regimes on soil properties. At low-intensity sheep grazing
(0·2–0·3 sheep/ha), the soil surface on the dunes
remained in an excellent condition. The surface had a good vegetative cover
and consisted of either loosely packed sand grains, or areas where the sand
grains were bonded together by clay and organic matter to form an organic
crust. The total carbon content of the 0–2 cm depth of soil was
0·86%. Both soil surfaces have a high infiltration rate (i.e.
>30 mm/h) and also appear to contain stable microaggregates of parna
material distributed among the eolian sand grains. Very high-intensity goat
grazing (up to 4·0 goats/ha) rapidly depleted the perennial
grasses, killed most of the shrubs, and converted the soil surface on the
dunes to one highly susceptible to erosion by wind. The low total carbon
content (depth 0–2 cm) of 0·3% and absence of iron-stained
clay coatings on the sands further support this view. The surface soil on the
dunes in the very high-intensity goat-grazing plots consisted of either
loosely packed sand grains or areas where poorly orientated clays coated the
sand grains to form a strong, physical crust. We suggest that the physical
crust may cause a change in the hydrology of the land system which may enhance
the conditions for recruitment of unpalatable shrubs in the dune–swale
interface. This increase in unpalatable shrubs and decrease in perennial
grasses caused by the very high intensity goat grazing is therefore
detrimental to the long-term productivity of these semi-arid lands.
Environmental magnetism as a stream sediment tracer: an interpretation of the methodology and some case studies
Authors: Crockford R. H. , Fleming P. M.
Published: August 2004

A comprehensive sediment sampling program was undertaken in the upper Molonglo
catchment in south-eastern New South Wales to determine if mineral magnetics
could be used to estimate sidestream contribution at river confluences in this
environment. Some 12 confluences were examined over 1400 km
2 in 2 major basins and over 2 contrasting geological
types. Sediment samples were divided into 7 size classes and the following
magnetic properties measured: magnetic susceptibility at 2 frequencies,
isothermal remanent magnetisation at 3 flux densities, and anhysteristic
remanent magnetisation.
The sidestream inputs were calculated for each particle size class from the
range of magnetic parameters. Significant discrepancies and differences
appeared in the resultant sidestream inputs, and this paper outlines the
conclusions as to the reliability of the different analytical procedures. It
is shown that both the concentration and magnetic grain size of ferrimagnetic
minerals in the sediments must be taken into account. Where the difference in
magnetic grain size between the upstream and sidestream sediments is small,
the use of parameter crossplots or bulked magnetic ratios is generally not
appropriate. The use of mass (concentration) magnetic values may be better.
The difference in the demands of the crossplots and mass values methods is
that crossplots require a wide range of mass magnetic concentrations in each
branch, with the upstream and sidestream sediments having different magnetic
grain sizes, whereas the mass values procedure does best with a very limited
(but different) range of concentrations at the upstream and sidestream
branches, but similar magnetic grain sizes.
This paper provides an extensive discussion of the estimation technique using
different parameter combinations, and uses 3 contrasting confluences as case
studies.
Nitrogen mineralisation rates from soil amended with dairy pond waste
Authors: Noonan M. J. , Zaman M. , Cameron K. C. , Di H. J.
Published: August 2004

An open incubation and leaching study was conducted under controlled
temperature (25°C) and moisture conditions to measure the N mineralisation
rate in soil amended with dairy pond sludge. The dairy pond sludge was applied
at 3 different rates equivalent to 0, 200, and 400 kg N/ha. The incubation
was conducted at 3 different soil moisture potentials (0, -3, and -13 kPa).
Following each 2-week period of incubation, the soil was leached with 2 pore
volumes of deionised water to remove the mineralisation products.
Mineralisation products in the leachate and enzyme activities, microbial
biomass C and N, pH, and water-soluble C in the soil were determined. The
incubation lasted 18 weeks.
Rapid release of nitrate occurred during the first 6 weeks of incubation,
followed by a slow release over the remainder of the incubation period.
Although the total amount of N released in the 200 kg N/ha treatment (169
mg N/kg soil) was less than in the 400 kg N/ha treatment (206 mg
N/kg soil), when expressed as a percentage of the organic N applied, the
amount of N released at the lower rate (18·4%) was greater than
that at the higher rate of sludge treatment (13·0%). Rapid
nitrification decreased the soil leachate ammonium concentration and the soil
pH. Soil microbial biomass, water-soluble C, and deaminase activity were
significantly increased after the addition of dairy pond sludge. The increase
in soil microbial biomass observed was probably due to the increased
water-soluble C and nutrients that stimulated the soil microbial growth. The
rapid N release and nitrification rates observed were attributed to the low C
: N ratio (12·7), high ammonium content (145 mg N/kg) of the dairy
pond sludge used, and the optimum moisture and temperature conditions. The
narrow range of soil water potential conditions did not have any significant
effect on N release rate or amount.
Soil organic carbon, permanganate fractions, and the chemical properties of acidic soils
Authors: Moody P. W. , Yo S. A. , Aitken R. L.
Published: August 2004

Total organic carbon (TC) in 32 acidic surface (0–10 cm) soils was
divided into 3 fractions (C1, C2, and C3) based on oxidisability by different
strengths of KMnO4 (33 mM and 167 mM). With the
methodology used, ease of oxidation decreased in the order C1>C2>C3.
Several fundamental soil chemical properties were also determined, i.e. ECEC,
CEC at pH 6·5 (CEC6·5), slope of the
charge curve (ΔCEC), pH buffer capacity, (pHBC), P sorption capacity
using a single addition index (PSI150), and content of
organically complexed Al. All soils had pH (1:5 water) <6·5, and
comprised a wide range of soil types and clay contents.
Multiple step-up regression indicated that C fractions were significantly
(P < 0·05) correlated with ECEC, ΔCEC,
CEC6·5, and pHBC. These results reinforce the
critical importance of soil organic matter to the fundamental soil chemical
properties of predominantly variable charge soils. The intercorrelations
between the various oxidisable C fractions made it difficult to elucidate if
degree of oxidisability had any bearing on the reactivity of the organic
matter. ECEC was primarily correlated with C1, whereas all C fractions had
highly significant (P < 0·01) effects on
ΔCEC and pHBC. The fraction which was most difficult to oxidise, C3,
made a significant (P < 0·01) contribution to
CEC6·5 when combined with clay and ECEC in a
multiple regression equation. Generally, one or other of the C fractions was
better correlated with the fundamental soil chemical properties than TC. This
simple empirical fractionation of soil organic C may therefore be a useful
tool for assessing the effects of soil management on these properties.
Changes in kaolinite, vermiculite, and smectite clays after adsorption by hydroxy-chromium species
Authors: Volzone Cristina
Published: August 2004

Kaolinite, vermiculite, and montmorillonites were treated with solutions
containing hydroxy-chromium (OH-Cr) species. The OH-Cr solution was prepared
by adding 0·2 М NaOH to 0·1 М chromium nitrate solution
and allowing the solution to stand at 60°C for 1 day. The samples were
characterised by chemical analyses, N2
adsorption-desorption isotherms, and X-ray diffraction. The textural and
structural behaviours of kaolinite, vermiculite, and the montmorillonites were
analysed in the original samples and after treatment with the polymeric OH-Cr
species. The montmorillonites showed higher retention of chromium
(19·20%), higher basal spacing (2·06 nm), and higher
micropore surface area (276 m2/g) than the
vermiculite (3·70%, 1·49 nm, 13
m2/g) and kaolinite (1·15%,
0·73 nm, ~1 m2/g) clays after treatment
with the OH-Cr species. In contrast, the external surface area increased from
6 to 9 m2/g for kaolinite and from 18 to 24
m2/g for vermiculite, and decreased from 7 to 4
m2/g for montmorillonite after treatment with the
OH-Cr solution. The residual chromium, basal spacing, and texture of the clays
after treatment with the OH-Cr species were primarily related to the magnitude
of the negative charge originating from the octahedral sheet.
Proteoid root mats stabilise Hawkesbury Sandstone biomantles following fire
Authors: Gould Susan F.
Published: August 2004

The proteoid roots of Banksia serrata L. f. form a dense
mat which actively binds biomantle material. In this study, the proteoid root
mats of B. serrata L. f. were studied within the context
of repeating landscape elements to determine their impact on soil erosion
following fire. It was found that proteoid root mats on a Hawkesbury Sandstone
hillslope were extensive and positioned high in the soil profile at a time
when soils might otherwise be susceptible to soil erosion. On the basis of
this evidence, it is concluded that the proteoid roots
ofBanksia serrata L. f. stabilise Hawkesbury Sandstone
biomantles following bushfire.
Studies in the Genus Amanit a (Agaricales) in Australia
Authors: Wood A. E.
Published: August 2004

Descriptions are provided for 67 species, of which 34 are new, for Amanita
from Australia, mainly from New South Wales. A key is provided and line
drawings illustrate macro- and micro-characters of all species. The species
are discussed in relation to previous records of Australian species and also
in relation to the species found in related floras.
New Zealand floras and systematic botany: Progress and prospects
Authors: Garnock-Jones P. J. , Breitwieser I.
Published: August 2004

Botanists have produced vascular plant Floras of New Zealand at regular
intervals since 1775. The current tracheophyte Flora series is nearing
completion, but early volumes already need major revision. There are few Flora
treatments covering algae and fungi. Moss and liverwort Floras are in early
stages, while the Lichen Flora is now under revision. Current research
attention is focused on revisions of critical groups, phylogenetic studies to
investigate generic circumscriptions or family placements, and provision of
new tools for plant identification. Plans are under way to produce an
Excursion Flora.
Fossil evidence for the onset of xeromorphy and scleromorphy in Australian Proteaceae
Authors: Hill Robert S.
Published: August 2004

The morphological response of leaves to low nutrient levels and low phosphorus
(scleromorphy) in particular, has become confused in the literature with the
response to low water levels (xeromorphy). However, the two can be reconciled
to some degree, particularly when it becomes clear that the earliest
Proteaceae in the fossil record are scleromorphic, but occurred in very wet
climates, where excessive water on the leaf surface was probably a major
problem. Unequivocal xeromorphic characters are interpreted as those that
increase the boundary layer and thus reduce water loss per unit of leaf
surface area without improving water repellancy from the surface. The clearest
characters in this regard are the presence of stomata in pits, stomata
individually enclosed by raised structures or revolute leaf margins. None of
these characters appears prior to the Late Eocene in south-western Australia
and the Oligocene in south-eastern Australia, suggesting that xeromorphy arose
relatively late, at least in the areas wherefossil deposits occur. A dense
covering of trichomes, often interpreted as a xeromorphic response, is here
considered to have had the primary function of keeping water off the leaf
surface, although it may have been exapted to a xeromorphic function when dry
conditions arose. Thus scleromorphy and xeromorphy appear to have arisen at
distinctly different times in Australian Proteaceae, with the latter not being
a convincingly pre–Late Eocene phenomenon.
The Early History of the Proteaceae in Australia: the Pollen Record
Authors: Dettmann Mary E. , Jarzen David M.
Published: August 2004

The early history of the Proteaceae in Australia is traced from the record of fossil pollen that possess characters having taxonomic resolution among extant members of the family. Pollen characters useful for segregating subfamilies and generic groups are apertural number and form together with exine stratification and structure. When considered in conjunction with pollen shape, polarity, and size and exine sculpturing, they may be used to discriminate generic and/or species groups. The fossil pollen record suggests that the family originated in northern Gondwana during the late Cenomanian and radiated by as yet unidentified routes into southern high latitudes during the Turonian. There the family underwent substantial differentiation and expansion during Santonian–Maastrichtian times when at least four of the seven extant subfamilies evolved. Although diversification in Australia principally involved rainforest lineages (e.g.
Macadamia–Helicia, Carnarvonia, Gevuina) ancestors of some sclerophyllous taxa (e.g. Adenanthos) also differentiated; this occurred in a regionalised vegetation of mesotherm open-forests in which podocarps and araucarians were important. Subsequent (Paleocene–Eocene) diversification and consolidation of the family may have focused on introduction and expansion of sclerophyllous lineages (e.g. Isopogon, Petrophile), but rainforest elements (e.g. Embothrium) were also involved. The associated vegetation, which was regionalised, experienced considerable floristic modifications during this time with introductions and/or expansion of an array of angiosperm taxa, notably Casuarinaceae, Myrtaceae and Nothofagus. In southern regions a marked decline in proteaceous pollen diversity and abundance occurred near the end of the Eocene, whereas in north-eastern regions the decline may have been later, during the Miocene.
The American Proteaceae
Authors: Prance Ghillean T. , Plana Vanessa
Published: August 2004

The American Proteaceae are outliers from the main centres of diversity of the
family in Australia and South Africa. There are about 83 species in eight
genera which all belong to the monophyletic subfamily Grevilleoideae. Three
genera, Embothrium, Oreocallis and
Lomatia, are placed in the tribe Embothrieae
(sensu Johnson and Briggs), four
Euplassa, Gevuina,
Panopsis and Roupala in the
Macadamieae and the single genus Orites in the Oriteae.
There are five genera endemic to America and three also have species in
Australia and New Guinea (Gevuina,
Lomatia and Orites). The
Proteaceae appear to have arrived in South America via two routes. The larger
genera Euplassa, Panopsis and
Roupala, which are all endemic to America and have a
general distribution in northern South America and south-eastern Brazil, are
derived from Gondwanaland before it separated from South America. The
remaining genera are distributed either in temperate South America or in the
high Andes and appear to have arrived more recently via the
Australia–Antarctica–South American connection. Three of these
genera have species in both regions. The centres of species diversity of
Euplassa, Panopsis and
Roupala fall outside hypothesised forest refugia,
indicating that they are not true rainforest species but species of seasonal
habitats like those achieved at higher altitudes where they are commonly
found.
Two genera,Panopsis and Roupala,
have reached Central America after the central American land bridge was formed
six million years ago. The exact relationship to genera on other continents is
still unclear and there is a need for a cladistic biogeographic analysis of
the group based on both morphological and molecular data.
Proteaceae - Where are we?
Authors: Johnson L. A. S.
Published: August 2004

Developments in understanding of the Proteaceae since 1963 are briefly
reviewed and discussed in relation to morphological interpretation, DNA
studies, phytogeography and phylogeny. Some of the outstanding questions are
highlighted.
Starting Point
More than 30 years ago, Barbara Briggs and I (Johnson and Briggs 1963)
published a hypothesis of the phylogeny of Proteaceae, a family of great
interest for which no reasonably acceptable evolutionary history had been
proposed. Unfortunately, at the time we wrote this paper, we were misled by
conservative geologists who had not got around to accepting continental drift,
and our phytogeographic understanding was much distorted by this.
Twelve years later (Johnson and Briggs 1975) we refined our complex hypotheses
of phylogeny and phytogeography, in a symposium celebrating the great botanist
Robert Brown. At this time we had more information on morphology and also on
karyology. The latter subject, dealing with chromosome size and number, is
almost completely out of favour now; nevertheless, it embraces complex
character-states that need to be taken into account and assessed as to
synapomorphy.
In 1975, our approach was more explicitly one of phylogenetic analysis,
although we were not in a position to carry this out rigorously throughout,
and it was not computerised. We also accepted certain groupings of taxa that
we in fact felt might be paraphyletic with respect to others. We certainly did
not wish to include any polyphyletic groups, although it now appears that some
of our tribes and subtribes will need amendment to render them pure in this
respect.
The 1975 classification is of course definitely not now upheld by us in all
respects. Forinstance, we consider Bellendena to be most
appropriately treated as constituting a subfamily distinct from Persoonioideae
and indeed we encouraged the publication of Bellendenoideae (Weston 1995). We
are pleased to see that our 1975 classification and suggested phylogeny are
still serving as a take-off point for current re-assessment and that a good
deal of it stands up, but we do not take the formal view that it is in itself
a hypothesis to be tested, in the Popperian sense. There is little point in
indicating that parts of it are incorrect when in fact we have modified our
own thinking considerably in the light of findings over the past two decades.
Rather, concentration should be on honing and modifying such very complex
hypotheses, not so much in the spirit of disproving or corroborating as in
seeking closer approximations to the actual phylogeny and its representation,
as far as possible, in a classification.
I shall discuss briefly the areas in which progress has been or needs to be
made.
Pollen morphology of Eidotheoideae: Implications for phylogeny in the Proteaceae
Authors: Dettmann Mary E.
Published: August 2004

Pollen morphology of Eidothea zoexylocarya A.W.Douglas & B.P.M.Hyland is detailed from light and both scanning and transmissionelectron microscope analyses. Eidothea shares withPersoonia and several taxa within tribes Conospermeaeand Proteeae oblate, isopolar, triporate pollen with a tectateperforate-retitectate exine composed only of ektexine that thins and isdisrupted by lacunae and radial channels in the apertural regions. These characters have taxonomic resolution within the Proteaceae and suggest a link between Subfamily Eidotheoideae and Subfamilies Persoonioideae andProteoideae; however, sculpturing of Eidothea pollendiffers in fine detail from that reported from the Persoonioideae and Proteoideae. The fossil pollen taxaProteacidites nitidus Dudgeon andP. punctiporus Macphail & Truswell are similar inapertural characters but sculptural attributes are distinct and exinestratification and structure of the fossil taxa await documentation.
Models of the distribution and abundance of ground-dwelling mammals in the eucalypt forests of south-eastern New South Wales
Authors: Catling P. C. , Burt R. J. , Forrester R. I.
Published: August 2004

We examined the relationship between ground-dwelling mammals and the
environment within 500 000 ha of eucalypt forest in south-eastern New South
Wales. Ground-dwelling mammals were surveyed at 368 sites in 13 areas in
relation to four habitat variables/factors, seven environmental variables,
and two derived variables (‘disturbance’ and ‘prey
abundance’). Habitat variables are vegetative variables such as eucalypt
community and forest structure that may be altered by man (e.g. logging) or
natural disturbances (e.g. wildfire). Environmental variables are climatic or
topographic variables such as rainfall or lithology that cannot be altered by
man or natural disturbances.
Statistical models are presented of the distribution and abundance of
ground-dwelling mammals in temperate eucalypt forests. From studies of the
prediction of eucalypt species from environmental variables and the
distribution of arboreal marsupials it has been possible previously to map the
predicted density of arboreal marsupials for a large area of south-eastern New
South Wales. It would be difficult to do the same for the ground-dwelling
mammals because of the importance of structural variables and the influence of
disturbance on structure. However, there appears to be a positive relationship
between the abundance of some ground-dwelling mammals and environmental
variables such as the lithology nutrient rating.
Many past studies of fauna have stratified sampling on broad climatic and
terrain variables and not included an adequate proportion of the structural
variation, which may remain concealed as a large part of the unexplained
variation. This may be the single most important problem facing reliable
modelling and prediction of patterns of biodiversity in eucalypt forests.
Habitat use by the eastern horseshoe bat, Rhinolophus megaphyllus, in a fragmented woodland mosaic
Authors: Pavey Chris R.
Published: August 2004

I examined habitat use by eastern horseshoe bats,
Rhinolophus megaphyllus, in a fragmented woodland mosaic
in south-east Queensland, Australia. I predicted that the species would forage
within the remaining woodland remnants in the mosaic, because its flight
pattern and auditory system are adapted for locating and capturing prey in
cluttered habitat (i.e. close to and within vegetation). I studied habitat use
by light-tagging and radio-tagging bats that roosted in a disused mine in a
large woodland fragment. I observed bats within an area of 95 ha, which was
composed of grassland (71% of area), woodland (14%), and edge
habitat (boundary of woodland and grassland, and isolated trees in grassland
– 15%). Bats foraged in woodland and edge habitat but not over
grassland, and used woodland significantly more often than expected by its
availability. Commuting bats left the woodland fragment in which the roost was
located by one of two routes, both of which led into riparian woodland. One
route was entirely within woodland, whereas the other route crossed 250 m of
open ground. The study indicates that R. megaphyllus
should respond negatively to the fragmentation of woodland and forest because
this process will reduce the availability of its preferred foraging habitat.
YY1 inhibits the activation of the p53 tumor suppressor in response to genotoxic stress
Authors: Grönroos Eva , Terentiev Alexei A. , Punga Tanel , Ericsson Johan
Published: August 2004

The tumor suppressor p53 regulates cell-cycle progression and apoptosis in response to genotoxic stress, and inactivation of p53 is a common feature of cancer cells. The levels and activity of p53 are tightly regulated by posttranslational modifications, including phosphorylation, ubiquitination, and acetylation. Here, we demonstrate that the transcription factor Yin Yang 1 (YY1) interacts with p53 and inhibits its transcriptional activity. We show that YY1 disrupts the interaction between p53 and the coactivator p300 and that expression of YY1 blocks p300-dependent acetylation and stabilization of p53. Furthermore, expression of YY1 inhibits the accumulation of p53 and the induction of p53 target genes in response to genotoxic stress. YY1 also interacts with Mdm2 and the expression of YY1 promotes the assembly of the p53–Mdm2 complex. Consequently, YY1 enhances Mdm2-mediated ubiquitination of p53. Inactivation of endogenous YY1 enhances the accumulation of p53 as well as the expression of p53 target genes in response to DNA damage, and it sensitizes cells to DNA damage-induced apoptosis. Hence, our results demonstrate that YY1 regulates the transcriptional activity, acetylation, ubiquitination, and stability of p53 by inhibiting its interaction with the coactivator p300 and by enhancing its interaction with the negative regulator Mdm2. YY1 may, therefore, be an important negative regulator of the p53 tumor suppressor in response to genotoxic stress.
Rent sharing and the gender wage gap in Belgium
Authors: Rycx François , Tojerow Ilan
Published: August 2004

This study investigates, on the basis of a unique combination of two large‐scale data sets, how rent sharing interacts with the gender wage gap in the Belgian private sector. Empirical findings show that individual gross hourly wages are significantly and positively related to firm profits‐per‐employee even when controlling for group effects in the residuals, individual and firm characteristics, industry wage differentials and endogeneity of profits. Our instrumented wage‐profit elasticity is of the magnitude 0.06 and it is not significantly different for men and women. Of the overall gender wage gap (on average women earn 23.7 per cent less than men), results show that around 14 per cent can be explained by the fact that on average women are employed in firms where profits‐per‐employee are lower. Thus, findings suggest that a substantial part of the gender wage gap is attributable to the segregation of women in less profitable firms.
Direct and indirect gender discrimination in the South African labour market
Authors: Grün Carola
Published: August 2004

Only few studies have examined gender wage differentials and the extent of gender discrimination in South Africa. The following analysis covers several years after the end of Apartheid to describe the development of gender wage differentials and discrimination over time. Furthermore, it is also taken into account that labour force participants may have different probabilities of finding employment. By estimating selectivity corrected wage regressions it is not only possible to decompose wage gaps into the well‐known endowment and discrimination components but also detect the so‐called indirect effects that already arise at the selection into employment stage. Results obtained from this approach can drastically change the impression of wage discrimination gained from standard decomposition techniques. African women were found to increasingly suffer from discrimination at the hiring stage, whereas White women are more affected by direct wage discrimination.
Contribution to the identification of linear compartmental systems
Authors: Hebri B. , Cherruault Y.
Published: August 2004

This paper studies the existence and uniqueness of parameters identification in linear compartmental systems using successive resolutions of linear algebraic systems. These results can be exploited to build up simple numerical algorithms involving only algebraic linear systems. Compartmental analysis is the main mathematical technique for modelling phenomena arising in biology and medicine.
Postmodernism and fuzzy systems
Authors: Ligorio Tiziana
Published: August 2004

Affinities and shared ideas may be found at the foundations of both fuzzy set theory and the western philosophical movement commonly referred to as Postmodernism. The interest in highlighting these affinities is driven by the fact that the ideas and beliefs that are questioned by both these movements are exactly those which stand (or used to stand) as foundations of both western philosophy and science, and have their roots in an Aristotelian view of the world. By direct comparison between concepts drawn from passages of the main philosophers of the Postmodern movement and fundamentals of fuzzy set theory, parallelisms and commonalities are brought to the surface.
Success and failure mechanisms of public private partnerships (PPPs) in developing countries
Authors: Jamali Dima
Published: August 2004

The concept of public private partnerships (PPPs) has attracted worldwide attention and acquired a new resonance in the context of developing countries. PPPs are increasingly heralded as an innovative policy tool for remedying the lack of dynamism in traditional public service delivery. However PPPs have also become mired in a muddle of conceptual ambiguities. This paper sheds light on the PPP concept and the rationale for invoking private participation in developing countries. It also identifies critical success factors and policy requirements for successful PPP implementation. Finally, the paper presents a case study assessment of a post‐war PPP initiative in the Lebanese telecommunications sector and draws out lessons for improving the effectiveness and viability of PPP projects in the context of developing countries.
Partnerships in oil and gas production‐sharing contracts
Authors: Pongsiri Nutavoot
Published: August 2004

In countries with large or potentially large oil and gas deposits, the resource and its extraction tend to become vital cornerstones of the economy. However, uncertainties involved in finding commercial quantities of oil and gas and the intensive capital required for undertaking exploration and production result in significant business risks. The petroleum fiscal systems in many developing countries are now opting for production‐sharing contracts (PSC) as a new model of agreement for the exploration and production of oil and gas resources. This paper extends the principal‐agent theory to foster understanding of partnership between the host government and its foreign contractor in the realm of PSC. The theory highlights the importance of moral hazard and adverse‐selection problems. To avoid these uncertainties and asymmetric information, the principal (national oil company) needs to design an incentive contract that induces the agent (international oil company (IOC)) to undertake actions that will maximise the principal's welfare. Under a PSC, the state has to offer contract terms that are attractive enough for the IOC to enter into an agreement. At the same time, the terms must allow the state to receive maximum economic returns from the venture.
Quality as pedagogy of confinement: is there an alternative?
Authors: Gibbs Paul , Iacovidou Melpo
Published: August 2004

This paper argues for good higher education in which academics and students take responsibility for their scholarly activities. This ought to be the goal for higher education, not the fulfilment of quality criteria that may fail to capture the essences of an educated person. This proposal is offered, in part, as a response to the UK government's recent White Paper – on the future of higher education.
What can one learn from experiments about the elusive transition state?
Authors: Chang Iksoo , Cieplak Marek , Banavar Jayanth R. , Maritan Amos
Published: August 2004

We present the results of an exact analysis of a model energy landscape of a protein to clarify the idea of the transition state and the physical meaning of the ϕ values determined in protein engineering experiments. We benchmark our findings to various theoretical approaches proposed in the literature for the identification and characterization of the transition state.
Characterization of SLAC: A small laccase from Streptomyces coelicolor with unprecedented activity
Authors: Machczynski Michael C. , Vijgenboom Erik , Samyn Bart , Canters Gerard W.
Published: August 2004

Laccases and other four‐copper oxidases are usually constructed of three domains: Domains one and three house the copper sites, and the second domain often helps form a substrate‐binding cleft. In contrast to this arrangement, the genome of Streptomyces coelicolor was found to encode a small, four‐copper oxidase that lacks the second domain. This protein is representative of a new family of enzymes—the two‐domain laccases. Disruption of the corresponding gene abrogates laccase activity in the growth media. We have recombinantly expressed this enzyme, called SLAC, in Escherichia coli and characterized it. The enzyme binds four copper ions/monomer, and UV‐visible absorption and EPR measurements confirm that the conserved type 1 copper site and trinuclear cluster are intact. We also report the first known paramagnetic NMR spectrum for the trinuclear copper cluster of a protein from the laccase family. The enzyme is highly stable, retaining activity as a dimer in denaturing gels after boiling and SDS treatment. The activity of the enzyme against 2,6‐dimethoxyphenol (DMP) peaks at an unprecedentedly high pH (9.4), whereas the activity against ferrocyanide decreases with pH. SLAC binds negatively charged substrates more tightly than positively charged or uncharged molecules.