Developing a strategy for rehabilitating riparian vegetation of the Hawkesbury-Nepean River, Sydney, Australia

1994 ◽  
Vol 1 (3) ◽  
pp. 257 ◽  
Author(s):  
Jocelyn Howell ◽  
Doug Benson ◽  
Lyn McDougall
Keyword(s):  
Riparian Vegetation ◽  
Riparian Forest ◽  
Natural Vegetation ◽  
Tree Cover ◽  
The Past ◽  
European Settlement ◽  
Open Forest ◽  
Population Concentration

Situated on the southeastern coast at 34�S 151�E, Sydney was established in 1788 as Australia's first permanent European settlement. Clearing of natural vegetation and environmental degradation associated with the country's largest population concentration over the past 200 years have severely affected the nearby Hawkesbury-Nepean River. A strategy for rehabilitation of the riparian vegetation to conserve and enhance the natural conditions remaining along the river, with particular emphasis on habitat and natural biodiversity, has been developed. The study area encompassed the most modified part of the river, where it passes alternately through 80 km of sandstone terrain, where the natural vegetation of waterside scrub backed by open-forest remains largely unchanged, and 135 km of floodplain terrain, where most of the indigenous tall open-forest has been cleared and associated wetlands have been greatly modified. Indigenous riparian zone vegetation was recognized as critical to the maintenance of river health, providing a reservoir of biodiversity as a major value, upon which other values, including enhancement of water quality, bank stablility and erosion control, depend. As 47 per cent of study area riverbank was found to have less than 25 per cent tree cover, the strategy recommended that all remnant native vegetation and remnant native trees along the river be protected and that a substantial long-term aim should be the establishment of a 50-metre wide strip of native riparian forest vegetation on each bank along the full length of the river, to be linked ultimately with other areas of natural vegetation on the floodplain. To provide practical resources for revegetation, the strategy assembled a botanical database, including maps showing present tree cover and the past extent of floodplain vegetation types, descriptions and locations of sites where significant native riparian vegetation remains, ecological information on approximately 300 locally indigenous riparian and wetland plant species, guidelines on selection of appropriate species, replanting methods and determination of priorities at both site and landscape scale.

scholarly journals Seismology of Pulsating Ap Stars: Results From The Past Decade, Prospects For The Next

1993 ◽  
Vol 139 ◽  
pp. 122-131
Author(s):  
Jaymie M. Matthews
Keyword(s):  
Main Sequence ◽  
Rotation Period ◽  
The Past ◽  
Low Degree ◽  
Ap Stars ◽  
Ir Photometry ◽  
Roap Star ◽  
High Overtone

AbstractSince the discovery of the first rapidly oscillating Ap (roAp) star in 1978 by Kurtz, this class of magnetic chemically-peculiar pulsators has grown to over two dozen. The eigenfrequency spectra of roAp stars (with periods of ∼ 6 – 15 min) are consistent with nonradial p- modes of low degree and high overtone n, not unlike the Sun's five-minute oscillations seen in integrated light. However, unlike the Sun, the strong global dipole fields of roAp stars significantly affect the pulsations.Although much of the effort in the last decade has been towards detecting new roAp candidates and refining the frequencies of known variables, initial “seismic” analyses have already yielded important results. Measurements of fundamental frequency spacings constrain the luminosities and radii of some roAp stars. In addition, mode splitting provides: (1) an independent determination of rotation period, even in the absence of longer-term light variations; (2) limits on the rotational inclination i and magnetic obliquity β; and (3) an indication of the relative internal field strengths of certain roAp stars. Very recently, the temperature - optical depth structure of the atmosphere of HR 3831 was inferred from optical and IR photometry of its oscillations.Judging from current developments, the next decade promises exciting results on both observational and theoretical fronts. Several roAp stars have now been monitored for over a decade, allowing us to investigate long-term period changes due to evolution, binarity, etc. Eigenfrequency models for stars in the mass and radius range appropriate for Ap stars are becoming available, as well as explicit treatments of the perturbations due to magnetic fields. Armed with these, we may be able to place some roAp stars on a theoretical (or “asteroseismological H-R“) diagram to derive independently their masses and main-sequence ages.

scholarly journals Radiocarbon and 11-Year Variations of Cosmic Rays

Radiocarbon ◽  
1993 ◽  
Vol 35 (3) ◽  
pp. 347-350 ◽  
Author(s):  
A. A. Burchuladze ◽  
S. V. Pagava ◽  
G. I. Togonidze ◽  
M. V. Avtandilashvili
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
Complex Problem ◽  
Short Term ◽  
The Past ◽  
Terrestrial Origin ◽  
Astrophysical Phenomena

B. P. Konstantinov and G. E. Kocharov (1965, 1967) addressed the complex problem of astrophysical phenomena and radiocarbon. Currently available data show that the determination of cosmogenic 14C in accurately dated samples of terrestrial and atmospheric origin is one of the most reliable and promising methods for studying cosmic-ray variations in the past. 14C dating samples of terrestrial origin has helped solve the problem of long-term (100 yr or more) 14C variations and, accordingly, of cosmic-ray variations in the past. Short-term (ca. 11 yr or less) variations are still under investigation (Alexeyev et al. 1971; Damon, Long and Wallick 1973).

scholarly journals Relationships between mature trees and fire fuel hazard in Australian forest

2018 ◽  
Vol 27 (5) ◽  
pp. 353 ◽  
Author(s):  
Nicholas Wilson ◽  
Geoffrey J. Cary ◽  
Philip Gibbons
Keyword(s):  
Vegetation Cover ◽  
Fuel Reduction ◽  
Mature Trees ◽  
Quadratic Mean ◽  
European Settlement ◽  
Open Forest ◽  
Eastern Australia ◽  
Two Measures ◽  
The Mean

Increasing density of mid-storey vegetation since European settlement has been observed in forests and woodlands in several parts of the world and may result in greater fire fuel hazard. This phenomenon is often attributed to a longer interval between fires since European settlement, but may also be influenced by tree removal during the same period. We hypothesised that the number of mature trees in a stand reduces mid-storey vegetation cover and the associated fire fuel hazard through competition. To test this hypothesis, we examined associations between mid-storey cover and fire fuel hazard and the mean diameter of trees within stands of open forest and woodland in south-eastern Australia, a region prone to wildfires. We found that vegetation cover between 2 and 4 m and 4 and 6 m above the ground and two measures of fire fuel hazard were negatively associated with the quadratic mean tree diameter. Our results suggested that the removal of mature trees since European settlement may have triggered tree and shrub regeneration, resulting in higher mid-storey cover and fire fuel hazard. Thus, managing stands for the persistence and replacement of mature trees may contribute to long-term fuel reduction in Australian forests and woodlands.

scholarly journals PROBLEMS OF CONFIRMATION OF THE AMOUNTS OF INCOME AND EXPENSES THAT ARISE IN ACCOUNTING FOR LONG-TERM DEBT

2020 ◽  
pp. 534-541
Author(s):  
T. Paientko
Keyword(s):  
Income Tax ◽  
Effective Rate ◽  
Review Of The Literature ◽  
Unified Approach ◽  
The Past ◽  
Risk Free Rate ◽  
Standard Operations ◽  
Free Rate

The article is devoted to solving the problematic issues of confirming the amounts of income and expenses that arise in accounting for long-term debt. A review of the literature has shown that domestic researchers do not pay enough attention to the method of determining the effective rate in various situations. It is incorrect to use the approaches of western researchers in determining the effective rate, as in Ukraine there is no unified approach for determining a risk-free rate. The purpose of the article is to justify the approaches to determining the effective interest rate when accounting for long-term debt in order to reflect correctly income and expenses arising from the discount calculation. Over the past few years, during tax audits, tax inspectors do not recognize or recognize income and expenses of income taxpayers that arise from the reflection of the discount in an incomplete amount. As a result, the taxpayers have income tax arrears, the amounts of which they do not agree with, and therefore they must go to court. The issue of confirmation of the amount of income or expenses arising as a result of reflection of the discount is controversial and complicated, therefore often requires the involvement of a forensic expert economist. In practice, there are nonstandard situations, namely: reflection in the accounting of long-term debt with an uncertain maturity; – reflection in the accounting of interest-free financial aid; reflection in the accounting of non-standard loans. It has been determined that the source of the problem is the lack of common approaches to justify the effective rate used in discounting. The court practice of settling disputes between taxpayers and the tax service has been analyzed. It is grounded, in what non-standard operations problems can arise in determining the effective rate. It is determined what approaches to the determination of discount rate should be applied in the realities of Ukraine. It has been substantiated that in order to protect the position of judicial experts when preparing opinions on the issues of reflection of income and costs arising from the discount, it is necessary to develop and approve the methodology for determining the effective rate for calculating the discount.

scholarly journals ECOLOGIA DE PEIXES DE RIACHOS INTERMITENTES

2021 ◽  
Vol 25 (02) ◽  
pp. 605-619
Author(s):  
Bianca de Freitas Terra ◽  
◽  
Elvio Sergio Figueredo Medeiros ◽  
Jorge Iván Sánchez Botero ◽  
José Luis Costa Novaes ◽  
...  
Keyword(s):  
Arid Region ◽  
Riparian Vegetation ◽  
Hydrological Cycle ◽  
Future Research ◽  
Intermittent Streams ◽  
Species Introduction ◽  
The Past ◽  
Semi Arid Region ◽  
Semi Arid

The ecology of fish from intermittent streams in the Brazilian semi-arid region is still little known. In the past twenty years, the number of researchers dedicated to this topic has increased considerably. However, significant gaps still exist when compared to the perennial streams of other regions of Brazil. Questions that address seasonal variations come up against the determination of capture methods and techniques that are efficient in the different phases of the hydrological cycle. In addition, techniques widely used in perennial systems, such as electrofishing, in most cases, have not been effective. Aspects related to biology, physiology, behavior, functional and taxonomic ecology of fish still need to be investigated taking into account seasonal and spatial scale variations. In view of the growing transformation imposed on the Brazilian semi-arid region by the extensive use of natural resources and by climate change, aquatic environments and their biodiversity are threatened by the transformation of riparian vegetation, the sewage release, the species introduction, the modification of its course and artificial perennialization. Thus, we will present and discuss, in this paper, the studies developed on the ecology of fish in the intermittent streams of the Brazilian semi-arid region and the gaps and challenges to be faced by future research.

People and Change in Indigenous Australia

2017 ◽  
Keyword(s):  
Social Dynamics ◽  
Theoretical Perspective ◽  
Indigenous Australians ◽  
Racial Relations ◽  
The Past ◽  
European Settlement ◽  
Indigenous Australia ◽  
The Social ◽  
Regional Histories

Since the advent of European settlement, indigenous Australians have been subject to continual change and entrenched inequality. This has been their shared experience even as regional histories have diverged. These essays address the lives of indigenous Australians through a focus on the person. Various contexts are described including family and community groups, regional diaspora and inter-racial relations, along with a striking range of experience, from indigenous heavy metal gangs and rebellious, forthright women to the social dynamics of childhood and the effects of long-term unemployment. Issues are discussed against a backdrop of different regions including the remote north, the desert center, and the densely populated southeast of Australia.Convinced that accounts of indigenous Australians must become more dynamic and diverse, People and Change traces the development of Australianist ethnography as a tool for understanding personhood and places this research in a comparative and theoretical perspective. The collection provides new and nuanced insights on the past, the present and likely trajectories of indigenous Australians today.

scholarly journals 2.2.3 The Long Term Population of Interplanetary Micrometeoroids

1976 ◽  
Vol 31 ◽  
pp. 232-232
Author(s):  
G. Poupeau ◽  
R.M. Walker ◽  
E. Zinner ◽  
D. Morrison
Keyword(s):  
Solar Flare ◽  
Free Space ◽  
Lunar Regolith ◽  
Lunar Soil ◽  
The Past ◽  
Ion Probe ◽  
Space Data ◽  
The Relationship

Three problems will be discussed: A) The relationship between mlcro-meteoroids and solar flare particles averaged over the recent geologic past (~1 my); B) the past record of this relationship as measured in lunar soils and lunar and meteoritic breccias; C) the determination of the time at which different extraterrestrial samples were exposed to free space. Data bearing on these points obtained from studies of special lunar rocks and from measurements on individual crystals removed from lunar cores will be presented. Progress in using ion-probe mass spectrometry to link measurements of micro-impact craters with the past properties of the solar wind will also be discussed. Comparing microcraters and solar flare tracks in individual crystals from lunar cores, we find no evidence of any extraordinary variations for a time span covering an interval of ~109 yrs. Crystals 100µ to 400µ in size in mature lunar soil samples appear to have been exposed 3 to free space at the top of the lunar regolith for times from 103 to 104 yrs.

Use of GPS-Determined Attitude in Combination with Conventional Attitude Sensors

1994 ◽  
Vol 47 (3) ◽  
pp. 323-331 ◽  
Author(s):  
Therese Matheisen ◽  
Ole Ørpen
Keyword(s):  
Short Term ◽  
Combined System ◽  
The Past ◽  
Pitch Information ◽  
Update Rate ◽  
Gyro Compass ◽  
Better Than ◽  
Echo Sounder

Use of multi antenna GPS equipment for determination of a vessel's attitude holds some promise for the development of accurate and inexpensive attitude systems. An application for such systems might be to provide very accurate roll information for multibeam echo sounders.The present state-of-the-art GPS attitude systems cannot meet the required accuracy and update rate for such applications. GEOTEAM A/S has therefore developed a PC-based system which combines GPS-based attitude with roll and pitch information from a Vertical Reference Unit (VRU) and heading from a gyro compass.In such a combined system, the long-term high accuracy of a GPS-based attitude system is combined with the short-term accuracy and fast update rate of conventional VRUS and gyro compasses in order to achieve a resulting performance that is better than any of the systems. In effect, the GPS attitude is used to calibrate the VRU and the gyro compass in real time.During the past year extensive tests have been performed with a system using a Trimble VECTOR II GPS attitude system with a 1 metre baseline between the antennas, both on a van (with an inertial navigation system as reference) and on a vessel. During November and December 1993 further tests were made with an Ashtech 3DF attitude system with longer baselines (7·5 m). These tests were made on a vessel where the combined GPS/VRU attitude was fed into a multibeam echo sounder. These tests were performed in cooperation with Simrad Subsea A/S, the multibeam echo sounder EM 1000 manufacturer.

scholarly journals Fire hazard modulation by long-term dynamics in land cover and dominant forest type in eastern and central Europe

2020 ◽  
Vol 17 (5) ◽  
pp. 1213-1230 ◽  
Author(s):  
Angelica Feurdean ◽  
Boris Vannière ◽  
Walter Finsinger ◽  
Dan Warren ◽  
Simon C. Connor ◽  
...  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Biomass Burning ◽  
Forest Type ◽  
Fire Hazard ◽  
Fire Regimes ◽  
Early Holocene ◽  
Tree Cover ◽  
The Past

Abstract. Wildfire occurrence is influenced by climate, vegetation and human activities. A key challenge for understanding the risk of fires is quantifying the mediating effect of vegetation on fire regimes. Here, we explore the relative importance of Holocene land cover, land use, dominant functional forest type, and climate dynamics on biomass burning in temperate and boreo-nemoral regions of central and eastern Europe over the past 12 kyr. We used an extensive data set of Holocene pollen and sedimentary charcoal records, in combination with climate simulations and statistical modelling. Biomass burning was highest during the early Holocene and lowest during the mid-Holocene in all three ecoregions (Atlantic, continental and boreo-nemoral) but was more spatially variable over the past 3–4 kyr. Although climate explained a significant variance in biomass burning during the early Holocene, tree cover was consistently the highest predictor of past biomass burning over the past 8 kyr. In temperate forests, biomass burning was high at ∼45 % tree cover and decreased to a minimum at between 60 % and 70 % tree cover. In needleleaf-dominated forests, biomass burning was highest at ∼ 60 %–65 % tree cover and steeply declined at >65 % tree cover. Biomass burning also increased when arable lands and grasslands reached ∼ 15 %–20 %, although this relationship was variable depending on land use practice via ignition sources, fuel type and quantities. Higher tree cover reduced the amount of solar radiation reaching the forest floor and could provide moister, more wind-protected microclimates underneath canopies, thereby decreasing fuel flammability. Tree cover at which biomass burning increased appears to be driven by warmer and drier summer conditions during the early Holocene and by increasing human influence on land cover during the late Holocene. We suggest that long-term fire hazard may be effectively reduced through land cover management, given that land cover has controlled fire regimes under the dynamic climates of the Holocene.

scholarly journals Fire risk modulation by long-term dynamics in land cover and dominant forest type in Eastern and Central Europe

2019 ◽  
Author(s):  
Angelica Feurdean ◽  
Boris Vannière ◽  
Walter Finsinger ◽  
Dan Warren ◽  
Simon C. Connor ◽  
...  
Keyword(s):  
Land Cover ◽  
Fire Regime ◽  
Forest Type ◽  
Full Range ◽  
Fire Risk ◽  
Early Holocene ◽  
Tree Cover ◽  
Data Set ◽  
The Past

Abstract. Wildfire occurrence is influenced by climate, vegetation and human activities. A key challenge for understanding fire-climate-vegetation interactions is to quantify the effect vegetation has in mediating fire regime. Here, we explore the relative importance of Holocene land cover and dominant functional forest type, and climate dynamics on biomass burned in temperate and boreo-nemoral regions of Central and Eastern Europe over the past 12 ka BP years. We used an extensive data set of Holocene pollen and sedimentary charcoal records, in combination with climate simulations and novel statistical modelling. Biomass burned was highest during the early Holocene and lowest during the mid Holocene in all three ecoregions, but diverged more markedly over the past 3–4 ka BP. Although the climate was an important driver of fire hazard during the warm and dry early Holocene, tree cover was consistently the strongest predictor of past biomass burning. In temperate forests, biomass burned was high at ~ 45 % tree cover and decreased strongly towards 60 % tree cover. In needleleaf dominated forests, biomass burned was highest at ~ 60–65 % tree cover and abruptly declined at > 65 % tree cover. Biomass burned also increased when arable lands and grasslands reached ~ 15–20 %, although this relationship was highly dynamic depending on land use intensity throughout ignition and fuel type and availability. Our observations cover the full range of Holocene climate variability and land cover changes and illustrates that percentages of land cover is a key predictor of the probability of fire occurrence over timescales of centuries to millennia. We suggest that long-term fire risk may be effectively reduced through land cover management, given that land cover has controlled fire regimes under the dynamic climates of the Holocene.

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