Controlled burn and immediate mobilization of potentially toxic elements in soil, from a legacy mine site in Central Victoria, Australia
- Authors: Abraham, Joji , Dowling, Kim , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: Science of the Total Environment Vol. 616-617, no. (2018), p. 1022-1034
- Full Text: false
- Reviewed:
- Description: Conducting controlled burns in fire prone areas is an efficient and economic method for forest management, and provides relief from the incidence of high severity wild fires and the consequent damage to human property and ecosystems. However, similar to wild fires, controlled burns also affect many of the physical and biogeochemical properties of the forest soil and may facilitate remobilization of potentially toxic elements (PTEs) sequestered in vegetation and soil organic matter. The objective of the current study is to investigate the mobilization of PTEs, in Central Victorian forest soils in Australia after a controlled burn. Surface soil samples were collected two days before and after the controlled burn to determine the concentration of PTEs and to examine the physicochemical properties. Results show that As, Cd, Mn, Ni and Zn concentrations increased 1.1, 1.6, 1.7, 1.1 and 1.9 times respectively in the post-burn environment, whereas the concentrations of Hg, Cr and Pb decreased to 0.7, 0.9 and 0.9 times respectively, highlighting considerable PTE mobility during and after a controlled burn. Whilst these results do not identify very strong correlations between physicochemical properties of soil and PTEs in the pre- and post-burn environments, PTEs themselves demonstrated very strong and significant correlations. The mobilization of As, Hg and other toxic elements raise potential health concerns as the number of controlled burns are projected to increase in response to climate change. Due to this increased level of PTE release and remobilization, the use of any kinds of controlled burn must be carefully considered before being used as a forest management strategy in mining-affected landscapes which include areas with high PTE concentrations. © 2017 Elsevier B.V.
Effect of environmental factors on the germination and emergence of Salvia verbenaca L. cultivars (verbenaca and vernalis) : An invasive species in semi-arid and arid rangeland regions
- Authors: Javaid, Muhammad , Florentine, Singarayer , Ali, Hafiz , Weller, Sandra
- Date: 2018
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 13, no. 3 (2018), p. 1-20
- Full Text:
- Reviewed:
- Description: Salvia verbenaca (wild sage) is a commonly cultivated herbal medicine plant, which is native to the Mediterranean climate regions of Europe, Africa, Asia and the Middle East. However, it has become an invasive species in semi-arid and arid regions of southern Australia. Two varieties are present in this region, var. verbenaca and var. vernalis, each of which can be distinguished by differences in morphology and flowering period. Following trials to determine the optimum temperate regime for germination and response to light and dark, seeds of both varieties were tested for their response to variations in pH, moisture stress, salinity, and burial depth. The temperature and light trial was carried out using three different temperature regimes; 30/20C, 25/15C and 20/12C, and two light regimes; 12 hours light/12 hours dark and 24 hours dark, with var. vernalis responding to relatively higher temperatures than var. verbenaca. The germination rate of neither species was significantly inhibited by complete darkness when compared to rates under periodic light exposure. Both varieties germinated at near optimum rates strongly to very strongly in all pH buffer solutions, from pH 5 to pH 10, but they responded most strongly at neutral pH. Var. vernalis showed slightly more tolerance to reduced moisture availability, moderate to strong salinity, and burial depth, compared to var. verbenaca. However, even a fairly shallow burial depth of 2 cm completely inhibited germination of both varieties. Thus, in circumstances where both varieties are present in a soil seedbank, var. vernalis could be expected to establish in more challenging conditions, where moisture is limited and salinity is ‘moderate to high’, implying that it is a more serious threat for invasive weed in conditions where crop plants are already challenged.
Effects of prescribed fire and post-fire rainfall on mercury mobilization and subsequent contamination assessment in a legacy mine site in Victoria, Australia
- Authors: Abraham, Joji , Dowling, Kim , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: Chemosphere Vol. 190, no. (2018), p. 144-153
- Full Text: false
- Reviewed:
- Description: Prescribed fire conducted in fire-prone areas is a cost-effective choice for forest management, but it also affects many of the physicochemical and bio-geological properties of the forest soil, in a similar manner to wild fires. The aim of this study is to investigate the nature of the mercury mobilization after a prescribed fire and the subsequent temporal changes in concentration. A prescribed fire was conducted in a legacy mine site in Central Victoria, Australia, in late August 2015 and soil sample collection and analyses were carried out two days before and two days after the fire, followed by collection at the end of each season and after an intense rainfall event in September 2016. Results revealed the occurrence of mercury volatilization (8.3–97%) during the fire, and the mercury concentration displayed a significant difference (p < 0.05) before and immediately after the fire. Integrated assessment with number of pollution indices has shown that the study site is extremely contaminated with mercury during all the sampling events, and this poses a serious ecological risk due to the health impacts of mercury on human and ecosystems. In times of climate fluctuation with concomitant increase in forest fire (including prescribed fire), and subsequent precipitation and runoff, the potential for an increased amount of mercury being mobilized is of heighted significance. Therefore, it is recommended that prescribed fire should be cautiously considered as a forest management strategy in any mercury affected landscapes. © 2017 Elsevier Ltd
Environmental factors affecting the germination and emergence of white horehound (Marrubium vulgare L.) : A weed of arid-zone areas
- Authors: Javaid, Muhammad , Florentine, Singarayer , Ali, Hafiz , Chauhan, Bhagirath
- Date: 2018
- Type: Text , Journal article
- Relation: Rangeland Journal Vol. 40, no. 1 (2018), p. 47-54
- Full Text: false
- Reviewed:
- Description: White horehound (Marrubium vulgare L.), is a troublesome weed of arid zones, particularly in cropping and grazing areas. Understanding the seed ecology of white horehound is relevant to its management. The present study investigated the effects of temperature, light, osmotic potential, salinity, pH, and seeding depth on seed germination and seedling emergence of white horehound. Seeds germinated over a wide range of temperatures, with highest germination (100%) occurring at 25/20°C in either 12-h alternating light/dark or complete darkness. Germination decreased from 92% to 10% as the osmotic potential decreased from 0 to minus 0.6MPa and germination was completely inhibited at minus 0.8MPa. Increasing concentration of sodium chloride (salinity) from 50 to 150mM reduced germination from 68% to 11% but was completely inhibited at 200mM. Germination was not limited by variation of pH in solutions of pH 5 to pH 10. Maximum germination (99%) occurred at pH 7, but slightly decreased (90%) in acidic or alkaline media. Surface located seeds were highly germinable (87%) where seedling emergence significantly declined as seeding depth increased from 0.5 to 3cm. Nil seedling emergence was occurred at 4cm burial depth. Light significantly affected germination, time to 50% germination, mean germination time and germination index. Increasing osmotic and salinity stress both significantly increased the time to start germination, time to 50% germination, mean germination time, but decreased germination index. Burial depth adversely affected seedling emergence with surface located seedlings emerging earlier (4.2 days) compared with 20 days for seeds buried at 3cm. Results suggest that effective management of white horehound should consider targeting surface located seeds in combination with tools that induce minimal soil disturbance, particularly in relatively non-saline environments.
Environmental factors associated with the foliage cover of invasive fairy grass (Lachnagrostis filiformis) in Victoria, Australia
- Authors: Gosney, Kate , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: Environmental Science and Pollution Research Vol. 25, no. 2 (2018), p. 1350-1358
- Full Text: false
- Reviewed:
- Description: Fairy grass (Lachnagrostis filiformis) is an Australian native grass that has recently become a major concern for rural communities. Its dried inflorescences are blown by the wind and build up against fences and buildings, becoming a severe fire hazard. Understanding the ecology of fairy grass and its impacts on rural communities is relevant to its management. Four dry lake beds in Western Victoria were selected to determine if environmental factors, such as lake, location, direction, altitude and road type and the covariates of pH, soil salinity, soil moisture and distance to nearest road, are related to the presence of fairy grass. The ‘lake’ factor was the only environmental parameter that was significantly associated with the presence of this weed. © 2017, Springer-Verlag GmbH Germany.
Environmental factors effecting the germination and seedling emergence of two populations of an aggressive agricultural weed; Nassella trichotoma
- Authors: Humphries, Talia , Chauhan, Bhagirath , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 13, no. 7 (2018), p. 1-25
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- Description: Nassella trichotoma (Nees) Hack. ex Arechav. (Serrated tussock) is an aggressive globally significant weed to agricultural and natural ecosystems. Herbicide resistant populations of this C3 perennial weed have emerged, increasing the need for effective wide-scale cultural control strategies. A thorough seed ecology study on two spatially distinct populations of N. trichotoma was conducted on this weed to identify differences in important environmental factors (drought, salinity, alternating temperature, photoperiod, burial depth, soil pH, artificial seed aging, and radiant heat) which influence seed dormancy. Seeds were collected from two spatially distinct populations; Gnarwarre (38 O 9’ 8.892’’ S, 144 O 7’ 38.784’’ E) and Ingliston (37O 40’ 4.44’’ S, 144 O 18’ 39.24’’ E) in December 2016 and February 2017, respectively. Twenty sterilized seeds were placed into Petri dishes lined with a single Whatman® No. 10 filter paper dampened with the relevant treatments solution and then incubated under the identified optimal alternating temperature and photoperiod regime of 25C/ 15C (light/dark, 12h/12h). For the burial depth treatment, 20 seeds were placed into plastic containers (10cm in diameter and 6cm in depth) and buried to the relevant depth in sterilized soil. All trials were monitored for 30 days and germination was indicated by 5mm exposure of the radicle and emergence was indicated by the exposure of the cotyledon. Each treatment had three replicates for each population, and each treatment was repeated to give a total of six replicates per treatment, per population. Nassella trichotoma was identified to be non-photoblastic, with germination (%) being similar under alternating light and dark and complete darkness conditions. With an increase of osmotic potential and salinity, a significant decline in germination was observed. There was no effect of pH on germination. Exposure to a radiant heat of 120C for 9 minutes resulted in the lowest germination in the Ingliston population (33%) and the Gnarwarre population (60%). In the burial depth treatment, the Ingliston population and the Gnarwarre population had highest emergence of 75% and 80%, respectively at a depth of 1cm. Variation between the two populations was observed for the burial depth treatments; Gnarwarre had greater emergence than Ingliston from the 4cm burial depth, while Ingliston had greater emergence at the soil surface than Gnarwarre. The Gnarwarre population had greater overall germination than Ingliston, which could be attributed to the greater seed mass (0.86mg compared to 0.76mg, respectively). This study identifies that spatial variations in N. trichotoma’s seed ecology are present between spatially distinct populations.
Factors effecting the germination and emergence of a rangeland weed European heliotrope (Heliotropium europaeum L.)
- Authors: Humphries, Talia , Graz, Friedrich , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: Rangeland Journal Vol. 40, no. 6 (2018), p. 583-590
- Full Text: false
- Reviewed:
- Description: European heliotrope (Heliotropium europaeum L.) is an important weed in semiarid and arid Australia, due to its toxicity to livestock and its ability to out-compete crops for water and soil nutrients. It is an ephemeral species populations appear in high densities when conditions are favourable, but seeds remain dormant in the soil seedbank for extended periods of time. This study aimed to identify environmental factors that promoted the germination of this weed and factors that de-vitalise seeds. Seeds were collected from the Australian semiarid zone, at Nanya Research Station, New South Wales. The effects on seed germination and seedling emergence of H. europaeum of alternating temperature, photoperiod, drought, salinity, pH range, heat shock combined with smoke exposure, and burial depth were investigated. The highest germination rate was observed under the highest temperature regime, 30/20°C, under a photoperiod of 12 h light and 12 h dark. The weed germinated under moderate osmotic stress, but the highest germination occurred in the control treatment (no osmotic stress). The effect of salinity and pH on percentage germination was not significant. The effect of the heat shock and smoke treatment significantly reduced seed germination, with germination inhibited when seeds were exposed to 100°C for 3 min. Burial depth had a significant effect on seedling emergence, with a burial depth of 0.5 cm reducing the germination by
Germination ecology of Chloris truncata and its implication for weed management
- Authors: Chauhan, Bhagirath , Manalil, Sudheesh , Florentine, Singarayer , Jha, Prashant
- Date: 2018
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 13, no. 7 (2018), p. 1-13
- Full Text:
- Reviewed:
- Description: Chloris truncata is a significant weed in summer crops in the subtropical region of Australia. A study was conducted to evaluate the effect of environmental factors on germination and emergence of two populations of C. truncata. Overall, germination was not affected by the populations. Seeds germinated at a wide range of alternating day/night temperatures, suggesting that seeds can germinate throughout the spring, winter and autumn seasons. Seed germination was stimulated by the presence of light; however, 51 to 71% of these seeds still germinated in the dark. The sodium chloride concentration and osmotic potential required to inhibit germination of 50% of the population were 179 mM and -0.52 MPa, respectively. A high proportion of seeds germinated over a wide pH range (4 to 10). Seeds placed on the soil surface had greatest germination (67%) and a burial depth of 3 cm resulted in complete inhibition of emergence. The sorghum residue amount required to reduce emergence by 50% was 1.8 t ha-1. The results suggest that, although this weed will be favored in no-till systems, residue retention on the soil surface will help in reducing its infestation. Seed bank buildup can be managed by burying seeds below the depth of emergence. © 2018 Chauhan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
In vitro assessment of arsenic mobility in historical mine waste dust using simulated lung fluid
- Authors: Martin, Rachael , Dowling, Kim , Nankervis, Scott , Pearce, Dora , Florentine, Singarayer , McKnight, Stafford
- Date: 2018
- Type: Text , Journal article
- Relation: Environmental Geochemistry and Health Vol. 40, no. 3 (2018), p. 1037-1049
- Full Text: false
- Reviewed:
- Description: Exposure studies have linked arsenic (As) ingestion with disease in mining-affected populations; however, inhalation of mine waste dust as a pathway for pulmonary toxicity and systemic absorption has received limited attention. A biologically relevant extractant was used to assess the 24-h lung bioaccessibility of As in dust isolated from four distinct types of historical gold mine wastes common to regional Victoria, Australia. Mine waste particles less than 20 µm in size (PM20) were incubated in a simulated lung fluid containing a major surface-active component found in mammalian lungs, dipalmitoylphosphatidylcholine. The supernatants were extracted, and their As contents measured after 1, 2, 4, 8 and 24 h. The resultant As solubility profiles show rapid dissolution followed by a more modest increasing trend, with between 75 and 82% of the total 24-h bioaccessible As released within the first 8 h. These profiles are consistent with the solubility profile of scorodite, a secondary As-bearing phase detected by X-ray diffraction in one of the investigated waste materials. Compared with similar studies, the cumulative As concentrations released at the 24-h time point were extremely low (range 297 ± 6–3983 ± 396 µg L−1), representing between 0.020 ± 0.002 and 0.036 ± 0.003% of the total As in the PM20.
Influence of controlled burning on the mobility and temporal variations of potentially toxic metals (PTMs) in the soils of a legacy gold mine site in Central Victoria, Australia
- Authors: Abraham, Joji , Dowling, Kim , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: Geoderma Vol. 331, no. (2018), p. 1-14
- Full Text: false
- Reviewed:
- Description: Controlled burns also known as managed burns or prescribed fires conducted in fire-prone areas are an efficient and economic option to reduce the frequency and intensity of wildfires. The objective of this study is to investigate the remobilization of potentially toxic metals (PTMs) in the soils of a legacy gold mine site in Central Victoria, Australia after a controlled burn and to describe their temporal variations in concentrations. Soil samples were collected two days before, two days after and five times later (3, 6, 9, 12 months and after major rainfall) in the post-burn environment after a controlled burn, from the Maldon legacy mine site and analysed for PTM concentrations. The results revealed PTM mobilization after the burn and most of the PTMs (As, Cd, Cu, Mn, Ni, and Zn) evidenced an increase immediately after the burn but a reduction in the subsequent post-burn environment. The increase is postulated to be associated with addition of PTM enriched ash to the soil, while the decrease is due to the removal of ash and surface soil by wind activity as well as rainfall runoff and leaching. The PTM mobility is of specific concern due to the negative impacts on human and ecosystems health. Climate change and the resulting projection of increased forest fire frequency highlight the environmental significance, given the expected concomitant increase in PTM mobilization through wildfires and controlled burns. Hence, the practice of controlled burning should be carefully considered as a forest management option in any legacy mining areas and indeed in other areas where PTM contamination is reported. © 2018
Seed germination response of a noxious agricultural weed Echium plantagineum to temperature, light, pH, drought stress, salinity, heat and smoke
- Authors: Florentine, Singarayer , Weller, Sandra , King, Alannah , Florentine, Arunthathy , Dowling, Kim , Westbrooke, Martin , Chauhan, Bhagirath
- Date: 2018
- Type: Text , Journal article
- Relation: Crop and Pasture Science Vol. 69, no. 3 (2018), p. 326-333
- Full Text: false
- Reviewed:
- Description: Echium plantagineum is a significant pasture weed in the Mediterranean climatic zone of several countries, including Australia. This invasive weed, introduced as an ornamental into Australia (where it is known as Paterson's curse), quickly became established and is now a significant weed of agriculture. Although E. plantagineum is a well-established, highly competitive weed that thrives under disturbance and is tolerant of a wide variety of conditions, including varying soil moisture and drought, and some aspects of its ecology remain unknown. This study investigated germination response to temperature and light, pH, soil moisture, salinity, and pre-germination exposure of seed to heat and smoke. Temperature was found to be more influential on germination than light and the species is tolerant to a wide range of pH. However, available moisture may limit germination, as may elevated salinity. Management of this weed requires approaches that minimise soil seedbank input or prevent germination of soil seedbanks.
Emerging challenges and opportunities for education and research in weed science
- Authors: Chauhan, Bhagirath , Matloob, Amar , Mahajan, Gulshan , Aslam, Farhena , Florentine, Singarayer , Jha, Prashant
- Date: 2017
- Type: Text , Journal article
- Relation: Frontiers in Plant Science Vol. 8, no. (2017), p. 1-13
- Full Text:
- Reviewed:
- Description: In modern agriculture, with more emphasis on high input systems, weed problems are likely to increase and become more complex. With heightened awareness of adverse effects of herbicide residues on human health and environment and the evolution of herbicide-resistant weed biotypes, a significant focus within weed science has now shifted to the development of eco-friendly technologies with reduced reliance on herbicides. Further, with the large-scale adoption of herbicide-resistant crops, and uncertain climatic optima under climate change, the problems for weed science have become multi-faceted. To handle these complex weed problems, a holistic line of action with multi-disciplinary approaches is required, including adjustments to technology, management practices, and legislation. Improved knowledge of weed ecology, biology, genetics, and molecular biology is essential for developing sustainable weed control practices. Additionally, judicious use of advanced technologies, such as site-specific weed management systems and decision support modeling, will play a significant role in reducing costs associated with weed control. Further, effective linkages between farmers and weed researchers will be necessary to facilitate the adoption of technological developments. To meet these challenges, priorities in research need to be determined and the education system for weed science needs to be reoriented. In respect of the latter imperative, closer collaboration between weed scientists and other disciplines can help in defining and solving the complex weed management challenges of the 21st century. This consensus will provide more versatile and diverse approaches to innovative teaching and training practices, which will be needed to prepare future weed science graduates who are capable of handling the anticipated challenges of weed science facing in contemporary agriculture. To build this capacity, mobilizing additional funding for both weed research and weed management education is essential. © 2017 Chauhan, Matloob, Mahajan, Aslam, Florentine and Jha.
Herbicide efficacy for aquatic Alternanthera philoxeroides management in an early stage of invasion : Integrating above-ground biomass, below-ground biomass and viable stem fragmentation
- Authors: Clements, Daniel , Dugdale, Tony , Butler, Kym , Florentine, Singarayer , Sillitoe, Jim
- Date: 2017
- Type: Text , Journal article
- Relation: Weed Research Vol. 57, no. 4 (2017), p. 257-266
- Full Text: false
- Reviewed:
- Description: Alternanthera philoxeroides is a problematic invasive plant in many regions of the world that is difficult to control once naturalised. It poses a threat to agricultural productivity, biodiversity and social amenity values of aquatic environments. Significant research has been conducted internationally, regarding the efficacy of different herbicides for control of A. philoxeroides. However, no studies have looked at key aspects of control for effective management in an early stage of invasion of aquatic environments, hindering eradication and control programmes. This study evaluates the efficacy of herbicides and surfactants on key A. philoxeroides response metrics, including control of above-ground biomass, below-ground biomass and production of viable stem fragments. This study concluded that glyphosate (isopropylamine salt) minimises viable stem fragment production post-herbicide application, compared with imazapyr and metsulfuron, thus reducing the potential for dispersal throughout catchments and waterways. In contrast, imazapyr and metsulfuron provided more effective control than glyphosate for A. philoxeroides growing on exposed embankments. We propose that an effective management strategy for early invasion of aquatic A. philoxeroides, using herbicides, would be to conduct initial applications of glyphosate to control overwater biomass and limit dispersal of viable stem fragments. Once infestations have been forced back to the embankment, imazapyr or metsulfuron treatments will provide longer term control. © 2017 European Weed Research Society
Implications of narrow crop row spacing in managing weeds in mungbean (Vigna radiata)
- Authors: Chauhan, Bhagirath , Florentine, Singarayer , Ferguson, Connor , Chechetto, Rodolfo
- Date: 2017
- Type: Text , Journal article
- Relation: Crop Protection Vol. 95, no. (2017), p. 116-119
- Full Text: false
- Reviewed:
- Description: The mungbean production area is increasing in Australia due to increasing demand for the grain in Asian countries. However, the mungbean crop is generally grown with wide row spacing, and therefore, it is prone to heavy weed infestation which has a significant impact on the mungbean grain yield. Experiments were conducted in 2015 and 2016 to determine the row-spacing impact on crop yield and weed growth for mungbean grown in 25, 50, and 75 cm space rows. Row spacing did not affect weed biomass and mungbean grain yield when weeds were allowed to grow from crop sowing to maturity. However, narrower row spacing (25 and 50 cm) had lower weed biomass and higher grain yield when weeds were allowed to grow beyond 3 and 6 weeks after planting (WAP). Mungbean grown at 25 and 50 cm rows had 60-70% and 70-92% less weed biomass than the mungbean grown at 75 cm rows for the weeds grown beyond 3 and 6 WAP, respectively. In weed-free conditions, too, mungbean grain yields were greater in narrow rows than in wider rows. Weeds grown beyond 6 WAP did not affect grain yield of 25 and 50 cm rows but reduced mungbean yield with 75 cm rows. The practical implication of this study is that narrowing row spacing in mungbean could lead to reduced weed growth and seed production and increased crop yield. (C) 2016 Elsevier Ltd. All rights reserved.
Rainfall and grazing : Not the only barriers to arid-zone conifer recruitment
- Authors: Zimmer, Heidi , Florentine, Singarayer , Enke, Rita , Westbrooke, Martin
- Date: 2017
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 65, no. 2 (2017), p. 109-119
- Full Text: false
- Reviewed:
- Description: An understanding of the drivers of infrequent recruitment is fundamental in managing for species persistence. Callitris glaucophylla Joy Thomps. & L.A.S. Johnson (white cypress-pine) is a slow-growing, long-lived conifer, with a distribution that extends across arid Australia. Arid populations of C. glaucophylla are endangered in New South Wales, and are characterised by infrequent recruitment. We examined recruitment patterns of C. glaucophylla in differential grazing exclosures (excluding rabbits, excluding large herbivores or excluding both) and in unfenced areas. More recruitment occurred in rabbit-proof exclosures, compared with nearby large herbivore and control exclosures, although some rabbit-proof exclosures recorded no recruitment. Increases in recruitment at several long-term exclosures were associated with wet periods, as was recruitment at some unfenced sites. Apart from grazing and rainfall, recruitment was related to mature tree size and stand density (probably because of their influence on seed availability). These endangered arid C. glaucophylla woodlands are all that remains of a once extensive distribution, and are habitat for a suite of threatened species. Reduction in grazing pressure, particularly from rabbits, is clearly critical to maintain recruitment in these remnant populations. Chances of recruitment appear to be enhanced in low-density stands, around large trees, and in dune blow outs - fencing should focus on these areas. © 2017 CSIRO.
Risk of post-fire metal mobilization into surface water resources : A review
- Authors: Abraham, Joji , Dowling, Kim , Florentine, Singarayer
- Date: 2017
- Type: Text , Journal article , Review
- Relation: Science of the Total Environment Vol. 599-600, no. (2017), p. 1740-1755
- Full Text: false
- Reviewed:
- Description: One of the significant economic benefits to communities around the world of having pristine forest catchments is the supply of substantial quantities of high quality potable water. This supports a saving of around US$ 4.1 trillion per year globally by limiting the cost of expensive drinking water treatments and provision of unnecessary infrastructure. Even low levels of contaminants specifically organics and metals in catchments when in a mobile state can reduce these economic benefits by seriously affecting the water quality. Contamination and contaminant mobility can occur through natural and anthropogenic activities including forest fires. Moderate to high intensity forest fires are able to alter soil properties and release sequestered metals from sediments, soil organic matter and fragments of vegetation. In addition, the increase in post-fire erosion rate by rainfall runoff and strong winds facilitates the rapid transport of these metals downslope and downstream. The subsequent metal deposition in distal soil and water bodies can influence surface water quality with potential impacts to the larger ecosystems inclusive of negative effects on humans. This is of substantial concern as 4 billion hectares of forest catchments provide high quality water to global communities. Redressing this problem requires quantification of the potential effects on water resources and instituting rigorous fire and environmental management plans to mitigate deleterious effects on catchment areas. This paper is a review of the current state of the art literature dealing with the risk of post-fire mobilization of the metals into surface water resources. It is intended to inform discussion on the preparation of suitable management plans and policies during and after fire events in order to maintain potable water quality in a cost-effective manner. In these times of climate fluctuation and increased incidence of fires, the need for development of new policies and management frameworks are of heighted significance. © 2017 Elsevier B.V.
The unquantified risk of post-fire metal concentration in soil : A Review
- Authors: Abraham, Joji , Dowling, Kim , Florentine, Singarayer
- Date: 2017
- Type: Text , Journal article
- Relation: Water, Air, and Soil Pollution Vol. 228, no. 5 (2017), p. 1-33
- Full Text: false
- Reviewed:
- Description: Forest fire is a natural disturbance that occurs in many terrestrial ecosystems specifically in the semi-arid environments and is considered to be an important cause of environmental change. Though many causes of fire are identified, including lightning, volcanic eruption, power line sparks, etc., human involvement is the most significant factor. Fire events are able to alter the physical, chemical and biogeochemical properties of the soil and surface materials and are able to release major and trace metals into the environment. This may be more significant in mining-affected and industrial landscapes, where elevated concentrations of metals present in the soil. After the fire event, metals become more mobile due to the increase in soil surface exposure and the mobility associated with ash dispersal. This mobility may increase the bioavailability of the metals, which may generate water quality issues and may contribute to human and environmental health concerns. Even though, the influences of fire on many soil properties are well established, the behaviour of metals with respect to fire is not well investigated. However, a few studies report that major and trace metals include Cd, Cr, Co, Cu, Hg, Mn, Ni, Pb, Zn and As are mobilized after fire with increased concentrations in soil and water resources and this might pose a risk to human health and ecosystems. Climate change may increase the intensity, frequency and areal extend of fire events and hence increase the metal concentrations and their potential health impacts. This paper reviews post-fire (wild fire) mobility of metals in soil common in contaminated forest ecosystems. The human and ecological health risks of these metals are also considered. © 2017, Springer International Publishing Switzerland.
Weeds in a changing climate : Vulnerabilities, consequences, and implications for future weed management
- Authors: Ramesh, Kulasekaran , Matloob, Amar , Aslam, Farhena , Florentine, Singarayer , Chauhan, Bhagirath
- Date: 2017
- Type: Text , Journal article
- Relation: Frontiers in Plant Science Vol. 8, no. (2017), p. 1-13
- Full Text:
- Reviewed:
- Description: Whilst it is agreed that climate change will impact on the long-term interactions between crops and weeds, the results of this impact are far from clear. We suggest that a thorough understanding of weed dominance and weed interactions, depending on crop and weed ecosystems and crop sequences in the ecosystem, will be the key determining factor for successful weed management. Indeed, we claim that recent changes observed throughout the world within the weed spectrum in different cropping systems which were ostensibly related to climate change, warrant a deeper examination of weed vulnerabilities before a full understanding is reached. For example, the uncontrolled establishment of weeds in crops leads to a mixed population, in terms of C3 and C4 pathways, and this poses a considerable level of complexity for weed management. There is a need to include all possible combinations of crops and weeds while studying the impact of climate change on crop-weed competitive interactions, since, from a weed management perspective, C4 weeds would flourish in the increased temperature scenario and pose serious yield penalties. This is particularly alarming as a majority of the most competitive weeds are C4 plants. Although CO2 is considered as a main contributing factor for climate change, a few Australian studies have also predicted differing responses of weed species due to shifts in rainfall patterns. Reduced water availability, due to recurrent and unforeseen droughts, would alter the competitive balance between crops and some weed species, intensifying the crop-weed competition pressure. Although it is recognized that the weed pressure associated with climate change is a significant threat to crop production, either through increased temperatures, rainfall shift, and elevated CO2 levels, the current knowledge of this effect is very sparse. A few models that have attempted to predict these interactions are discussed in this paper, since these models could play an integral role in developing future management programs for future weed threats. This review has presented a comprehensive discussion of the recent research in this area, and has identified key deficiencies which need further research in crop-weed eco-systems to formulate suitable control measures before the real impacts of climate change set in. © 2017 Ramesh, Matloob, Aslam, Florentine and Chauhan.
An investigation of the effects of stage of ensilage on Nassella neesiana seeds, for reducing seed viability and injury to livestock
- Authors: Weller, Sandra , Florentine, Singarayer , Sillitoe, Jim , Grech, Charles , McLaren, David
- Date: 2016
- Type: Text , Journal article
- Relation: Scientific Reports Vol. 6, no. (2016), p. 1-7
- Full Text:
- Reviewed:
- Description: The noxious weed Nassella neesiana is established on a wide range of productive land throughout southeastern Australia. N. neesiana seeds, when mature, are sharp, causing injury to livestock, thus posing a problem in fodder bales. To reduce infestations of agricultural weeds in situ, production of silage from weed-infested pastures is practised as part of integrated weed management (IWM). However, there is little data to demonstrate whether this process is useful to reduce infestations or the harmful properties of N. neesiana. Therefore, the minimum duration of ensilage required to reduce the viability of N. neesiana seeds was investigated, both with and without addition of ensilage inoculants in this process. Also, the decreasing propensity of the seeds to injure livestock, after various times and conditions of ensilage, was assessed. Ensilage inoculant reduced seed germination probability to zero after 35 days. When no inoculant was added, zero viability was achieved after 42 days. A qualitative assessment of the hardness of ensilaged seeds found seed husks were softer (and therefore safer) after 42 days, whether inoculant was used or not. Therefore, we suggest that both the viability of N. neesiana seeds and hardness of seed casings are significantly reduced after 42 days, thereby reducing the risks of seed dispersal and injury to livestock.
Arid land invasive weed Salvia verbenaca L. (wild sage) : Investigation into seedling emergence, soil seedbank, allelopathic effects, and germination
- Authors: Fisher, R. , Florentine, Singarayer , Westbrooke, Martin
- Date: 2016
- Type: Text , Conference paper
- Relation: Twentieth Australian Weeds Conference
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- Description: y Salvia verbenaca L., wild sage (Lamiaceae) is native to western and southern Europe. In Australia S. verbenaca is considered an environmental weed with high invasiveness often growing on disturbed sites: tracks, roadsides and around earth tanks. Little is known about the ecology of this invasive species in Australia. Therefore, our objectives in this study were to determine: (i) seedling emergence in relation to sowing depth, (ii) density ofsoilseed bank, (iii) allelopathic effects, (iv) favourable conditions for seed germination of three month old and nine years old seeds, and (v) seed longevity. Of four burial depths, only surface sown seeds germinated and survived. From the soil seedbank, S. verbenaca density was 343 ± 198 m−2. For the allelopathic effects of S. verbenaca, neither the extract nor the leachate inhibited germination of L. sativa; however, the growth of the radicle of seedlings was shown to decrease. Germination was highest at 20°C under 12 h light/12 h dark. Burial of seeds in the field prior to germination reduced viability over time. Germination of three month old seed wassignificantly less than nine year old seed. In conclusion, it is clear that S. verbenaca functions as a casual weed in arid and semi-arid environments of Australia. Understanding the plants’ ecological characteristics in this study will help us take appropriate control measures for this species.