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Comparison of groundwater transit velocity estimates from flux theory and water table recession based approaches for solute transport

  • Authors: Rasiah, Velu , Armour, John
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Journal of Environmental Management Vol. 116, no. (February 2013 2013), p. 36-49
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  • Description: Reliable information in transit time (TT) derived from transit velocity (TV) for rain or irrigation water to mix with groundwater (GW) and the subsequent discharge to surface water bodies (SWB) is essential to address the issues associated with the transport of nutrients, particularly nitrate, from GW to SWB. The objectives of this study are to (i) compare the TV estimates obtained using flux theory-based (Fe) approach with the water table rise/recession (WT) rate approach and (ii) explore the impact of the differences on solute transport from GW to SWB. The results from a study conducted during two rainy seasons in the northeast humid tropics of Queensland, Australia, showed the TV varied in space and over time and the variations depended on the estimation procedures. The lateral TV computed using the WT approach ranged from 1.00 x 10(-3) to 2.82 x 10(-1) m/d with a mean of 6.18 x 10(-2) m/d compared with 2.90 x 10(-4) to 5.15 x 10(-2) m/d for Fr with a mean of 2.63 x 10(-2) m/d. The vertical TV ranged from 2.00 x 10(-3) to 6.02 x 10(-1) m/d with a mean of 1.28 x 10(-1) m/d for the WT compared with 6.76 x 10(-3)-1.78 m/d for the FT with a mean of 2.73 x 10(-1) m/d. These differences are attributed to the role played by different flow pathways. The bypass flow pathway played a role only in WT but not in FT. Approximately 86-95% of the variability in lateral solute transport was accounted for by the lateral TV and the total recession between two consecutive major rainfall events. A comparison of TT from FT and WT approaches indicated the laterally transported nitrate from the GW to the nearby creek was relatively 'new', implying the opportunity for accumulation and to undergo biochemical reactions in GW was low. The results indicated the WT approach produced more reliable TT estimates than FT in the presence of bypass flow pathways. (C) 2012 Elsevier Ltd. All rights reserved.
  • Description: C1

Decoupling between water column oxygenation and benthic phosphate dynamics in a shallow eutrophic estuary

  • Authors: Kraal, Peter , Burton, Edward , Rose, Andrew , Cheetham, Michael , Bush, Richard , Sullivan, Leigh
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Environmental Science and Technology Vol. 47, no. 7 (2013), p. 3114-3121
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  • Description: Estuaries are crucial biogeochemical filters at the land-ocean interface that are strongly impacted by anthropogenic nutrient inputs. Here, we investigate benthic nitrogen (N) and phosphorus (P) dynamics in relation to physicochemical surface sediment properties and bottom water mixing in the shallow, eutrophic Peel-Harvey Estuary. Our results show the strong dependence of sedimentary P release on Fe and S redox cycling. The estuary contains surface sediments that are strongly reducing and act as net P source, despite physical sediment mixing under an oxygenated water column. This decoupling between water column oxygenation and benthic P dynamics is of great importance to understand the evolution of nutrient dynamics in marine systems in response to increasing nutrient loadings. In addition, the findings show that the relationship between P burial efficiency and bottom water oxygenation depends on local conditions; sediment properties rather than oxygen availability may control benthic P recycling. Overall, our results illustrate the complex response of an estuary to environmental change because of interacting physical and biogeochemical processes. © 2013 American Chemical Society.

Effect of substrate on surface morphology and photocatalysis of large-scale TiO2 films

  • Authors: Lopez Vanegas, Lorena , Daoud, Walid , Dutta, Dushmanta , Panther, Barbara , Turney, Terence
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Applied Surface Science Vol. 265, no. (2013 2013), p. 162-168
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  • Description: Nanostructured TiO2 films were prepared on a variety of substrates, including acid frosted soda-lime glass, acid frosted soda-lime glass pre-coated with a SiO2 barrier layer, commercial glazed ceramic tile and 6061 aluminum alloy. For each substrate, the phase and microstructure of the films were determined to be exclusively anatase. However, the growth of the TiO2 crystallites, the film morphology and thickness varied substantially with substrate. Thermal stress, resulting from the difference in the coefficient of thermal expansion between the substrates and the films, contributed to the formation and propagation of cracks. This was most clearly observed on the films deposited on SiO2 barrier layer and aluminum. The photocatalytic activity of the TiO2 films deposited on glass with and without SiO2 barrier layer, ceramic, and aluminum was studied via UV decolorization of methyl orange in aqueous solution. Complete degradation rapidly occurred on the TiO2/glass and TiO2/SiO2 barrier layer films, but not with the ceramic or metal substrates. It appears that the photocatalytic activity of the films deposited on aluminum and ceramic substrates was affected by the quantity and the size of the anatase crystallites. The aluminum substrate promoted the formation of TiO2 films with the largest anatase crystallite size, exhibiting a cracked morphology, where as the ceramic substrate resulted in the formation of TiO2 films with large crystallite size in an island morphology.

Longer leukocyte telomeres are associated with ultra-endurance exercise independent of cardiovascular risk factors

Nonsmooth nonconvex optimization approach to clusterwise linear regression problems

  • Authors: Bagirov, Adil , Ugon, Julien , Mirzayeva, Hijran
  • Date: 2013
  • Type: Text , Journal article
  • Relation: European Journal of Operational Research Vol. 229, no. 1 (2013), p. 132-142
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  • Description: Clusterwise regression consists of finding a number of regression functions each approximating a subset of the data. In this paper, a new approach for solving the clusterwise linear regression problems is proposed based on a nonsmooth nonconvex formulation. We present an algorithm for minimizing this nonsmooth nonconvex function. This algorithm incrementally divides the whole data set into groups which can be easily approximated by one linear regression function. A special procedure is introduced to generate a good starting point for solving global optimization problems at each iteration of the incremental algorithm. Such an approach allows one to find global or near global solution to the problem when the data sets are sufficiently dense. The algorithm is compared with the multistart Späth algorithm on several publicly available data sets for regression analysis. © 2013 Elsevier B.V. All rights reserved.
  • Description: 2003011018

Salt Loading in Canola Oil Fed SHRSP Rats Induces Endothelial Dysfunction

  • Authors: Papazzo, Annateresa , Conlan, Xavier , Lexis, Louise , Charchar, Fadi , Lewandowski, Paul
  • Date: 2013
  • Type: Text , Journal article
  • Relation: PLoS ONE Vol. 8, no. 6 (2013), p.
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  • Description: This study aimed to determine if 50 days of canola oil intake in the absence or presence of salt loading affects: (1) antioxidant and oxidative stress markers, (2) aortic mRNA of NADPH oxidase (NOX) subunits and superoxide dismutase (SOD) isoforms and (3) endothelial function in SHRSP rats. SHRSP rats were fed a diet containing 10 wt/wt% soybean oil or 10 wt/wt% canola oil, and given tap water or water containing 1% NaCl for 50 days. Without salt, canola oil significantly increased RBC SOD, plasma cholesterol and triglycerides, aortic p22phox, NOX2 and CuZn-SOD mRNA, and decreased RBC glutathione peroxidase activity. With salt, canola oil reduced RBC SOD and catalase activity, LDL-C, and p22phox mRNA compared with canola oil alone, whereas plasma malondialdehyde (MDA) was reduced and RBC MDA and LDL-C were higher. With salt, the canola oil group had significantly reduced endothelium-dependent vasodilating responses to ACh and contractile responses to norepinephrine compared with the canola oil group without salt and to the WKY rats. These results indicate that ingestion of canola oil increases O2 - generation, and that canola oil ingestion in combination with salt leads to endothelial dysfunction in the SHRSP model. © 2013 Papazzo et al.
  • Description: 2003011096

Seawater-induced mobilization of trace metals from mackinawite-rich estuarine sediments

  • Authors: Wong, Vanessa , Johnston, Scott , Burton, Edward , Bush, Richard , Sullivan, Leigh , Slavich, Peter
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Water Research Vol. 47, no. 2 (2013), p. 821-832
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  • Description: Benthic sediments in coastal acid sulfate soil (CASS) drains can contain high concentrations (~1-5%) of acid volatile sulfide (AVS) as nano-particulate mackinawite. These sediments can sequester substantial quantities of trace metals. Because of their low elevation and the connectivity of drains to estuarine channels, these benthic sediments are vulnerable to rapid increases in ionic strength from seawater incursion by floodgate opening, floodgate failure, storm surge and seasonal migration of the estuarine salt wedge. This study examines the effect of increasing seawater concentration on trace metal mobilization from mackinawite-rich drain sediments (210-550

Simultaneous redox conversion of chromium(VI) and arsenic(III) under acidic conditions

  • Authors: Wang, Zhaohui , Bush, Richard , Sullivan, Leigh , Liu, Jianshe
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Environmental Science and Technology Vol. 47, no. 12 (2013), p. 6486-6492
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  • Description: Arsenic and chromium are often abundant constituents of acid mine drainage (AMD) and are most harmful as arsenite (As(III)) and hexavalent (Cr(VI)). To simultaneously change their oxidation state from As(III) to As(V), and Cr(VI) to Cr(III), is a potentially effective and attractive strategy for environmental remediation. The coabundance of As(III) and Cr(VI) in natural environments indicates their negligible direct interaction. The addition of H 2O2 enables and greatly accelerates the simultaneous oxidation of As(III) and reduction of Cr(VI). These reactions are further enhanced at acidic pH and higher concentrations of Cr(VI). However, the presence of ligands (i.e., oxalate, citrate, pyrophosphate) greatly retards the oxidation of As(III), even though it enhances the reduction of Cr(VI). To explain these results we propose a reaction mechanism where Cr(VI) is primarily reduced to Cr(III) by H2O2, via the intermediate tetraperoxochromate Cr(V). Cr(V) is then involved in the formation of •OH radicals. In the presence of ligands, the capacity of Cr(V) to form •OH radicals, which are primarily responsible for As(III) oxidation, is practically inhibited. Our findings demonstrate the feasibility for the coconversion of As(III) and Cr(VI) in AMD and real-world constraints to this strategy for environmental remediation. © 2013 American Chemical Society.

The historic importance of the dingo in aboriginal society in Victoria (Australia) : A reconsideration of the archival record

  • Authors: Cahir, David (Fred) , Clark, Ian
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Anthrozoos Vol. 26, no. 2 (2013), p. 185-198
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  • Description: Dingoes feature prominently in Australian Aboriginal Creation stories and are also widely regarded as having an intricate relationship with Aboriginal people. A large volume of anthropological work on the complex relationship between Australian Aboriginals and dingoes has determined a considerable uniformity in the human-dingo relationship across northern Australia. Whilst there are many parallels between northern and southern Aboriginal Australia, this reconsideration of the archival record explores the hitherto rarely considered evidence of the relationship between Aboriginal people, British colonizers in Victoria (south-eastern Australia), and dingoes. The data provide an insight into the unique relationship, which indicates some striking differences between northern and southern Aboriginal Australia; especially the utilitarian and symbolic significance of dingoes for Aboriginal communities in south-eastern Australia and how dingoes were used by both Aboriginal people and the colonial usurpers in a bid to spatially dislocate each other. © ISAZ 2013.
  • Description: 2003011040

The microinsurance market in Bangladesh : An analytical overview

  • Authors: Ahsan, Syed , Khalily, M. A. Baqui , Hamid, Syed , Barua, Shubhasish , Barua, Suborna
  • Date: 2013
  • Type: Text , Journal article
  • Relation: The Bangladesh Development Studies Vol. 36, no. 1 (2013), p. 1-54
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  • Description: This paper provides an analytical overview of the current state of the microinsurance market in Bangladesh comprising of products offered by commercial insurance companies, microfinance institutions (MFIs) and those by INAFI’s MIME programme. For the commercial life insurers, available products are characterised by a mix of inadequate risk coverage, excessively high premium rates unrelated to any plausible model of mortality of the insured, lengthy process of claim settlement and, above all, high costs of intermediation. Such products therefore appear unattractive to the vulnerable. The MFIs, on the other hand, mainly offer loan insurance thus minimising lenders’ risks and having a much quicker claim settlement process. Some MFIs also offer a variety of other products (notably, term life, health and livestock insurance). However, the health plans reviewed in the paper clarify that most of these are not examples of true insurance products since the bulk of the risk eventually remains with the insured. The requirement of cash transactions in each step of the way is a further drawback eroding popularity of the products. Finally, it is seen that, while INAFI has been implementing both term and endowment life policies, the premium structure appears rather steep vis-à-vis the cost of risks, presumably reflecting high costs of intermediation. In view of very limited competition in the market for commercial life coverage, regulatory directives may be targeted at improving competition in each segment of the market, thereby fostering innovation and fair play.

The requirement of having a body

  • Authors: Duffy, Michelle
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Geographical Research Vol. 50, no. 2 (2013), p. 130-136
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  • Description: In a project that explores the role affect plays in processes of place-making, children aged 10–12 were asked to record meaningful sounds about their home spaces. This focus on sound and listening reminds us that the body is very much entangled in, and indeed fundamental to, processes of subjectivity and place-making. The methodologies used in this work are, therefore, about techniques of researching through bodies, rather than an examination about bodies. This paper explores what researching place through bodies means, with a close reading of one particular response from a young girl who captured the sounds of her friend playing on the slide. In a conversation about this captured sound, she explained that the slide was where she can be with one special person who ‘understands’, but how she presented this relationship was in the movement of the body moving down the slide and the expression of affect and its release – a joyous call of ‘wheeee’ as the body slid down. This paper seeks to contribute to discussions around the moving and feeling body as a means to think geographically about the requirement of having a body, how the physicality of the body and its actions with (and within) affective states constitute a sense of place and notions of connectedness.

The Zinc Transporter, Slc39a7 (Zip7) Is Implicated in Glycaemic Control in Skeletal Muscle Cells

  • Authors: Myers, Stephen , Nield, Alex , Chew, Guatsiew , Myers, Mark
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Plos One Vol. 8, no. 11 (November 2013 2013), p. 15
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  • Description: Dysfunctional zinc signaling is implicated in disease processes including cardiovascular disease, Alzheimer's disease and diabetes. Of the twenty-four mammalian zinc transporters, ZIP7 has been identified as an important mediator of the 'zinc wave' and in cellular signaling. Utilizing siRNA targeting Zip7 mRNA we have identified that Zip7 regulates glucose metabolism in skeletal muscle cells. An siRNA targeting Zip7 mRNA down regulated Zip7 mRNA 4.6-fold (p = 0.0006) when compared to a scramble control. This was concomitant with a reduction in the expression of genes involved in glucose metabolism including Agl, Dlst, Galm, Gbe1, Idh3g, Pck2, Pgam2, Pgm2, Phkb, Pygm, Tpi1, Gusb and Glut4. Glut4 protein expression was also reduced and insulin-stimulated glycogen synthesis was decreased. This was associated with a reduction in the mRNA expression of Insr, Irs1 and Irs2, and the phosphorylation of Akt. These studies provide a novel role for Zip7 in glucose metabolism in skeletal muscle and highlight the importance of this transporter in contributing to glycaemic control in this tissue.

Urotensin-II system in genetic control of blood pressure and renal function

  • Authors: Debiec, Radoslaw , Christofidou, Paraskevi , Denniff, Matthew , Bloomer, Lisa , Bogdanski, Pawel , Wojnar, Lukasz , Musialik, Katarzyna , Charchar, Fadi , Thompson, John , Waterworth, Dawn , Song, Kijoung , Vollenweider, Peter , Waeber, Gerard , Zukowska-Szczechowska, Ewa , Samani, Nilesh , Lambert, David , Tomaszewski, Maciej
  • Date: 2013
  • Type: Text , Journal article
  • Relation: PLoS ONE Vol. 8, no. 12 (2013), p.
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  • Description: Urotensin-II controls ion/water homeostasis in fish and vascular tone in rodents. We hypothesised that common genetic variants in urotensin-II pathway genes are associated with human blood pressure or renal function. We performed familybased analysis of association between blood pressure, glomerular filtration and genes of the urotensin-II pathway (urotensin-II, urotensin-II related peptide, urotensin-II receptor) saturated with 28 tagging single nucleotide polymorphisms in 2024 individuals from 520 families; followed by an independent replication in 420 families and 7545 unrelated subjects. The expression studies of the urotensin-II pathway were carried out in 97 human kidneys. Phylogenetic evolutionary analysis was conducted in 17 vertebrate species. One single nucleotide polymorphism (rs531485 in urotensin-II gene) was associated with adjusted estimated glomerular filtration rate in the discovery cohort (p = 0.0005). It showed no association with estimated glomerular filtration rate in the combined replication resource of 8724 subjects from 6 populations. Expression of urotensin-II and its receptor showed strong linear correlation (r = 0.86, p< 0.0001). There was no difference in renal expression of urotensin-II system between hypertensive and normotensive subjects. Evolutionary analysis revealed accumulation of mutations in urotensin-II since the divergence of primates and weaker conservation of urotensin-II receptor in primates than in lower vertebrates. Our data suggest that urotensin-II system genes are unlikely to play a major role in genetic control of human blood pressure or renal function. The signatures of evolutionary forces acting on urotensin-II system indicate that it may have evolved towards loss of function since the divergence of primates. © 2013 Debiec et al.

Assessment of spatiotemporal varying relationships between rainfall, land cover and surface water area using geographically weighted regression

  • Authors: Brown, Stuart , Versace, Vincent , Laurenson, Laurie , Ierodiaconou, Daniel , Fawcett, Jonathon , Salzman, Scott
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Environmental Modeling and Assessment Vol. 17, no. 3 (2012), p. 241-254
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  • Description: Traditional regression techniques such as ordinary least squares (OLS) are often unable to accurately model spatially varying data and may ignore or hide local variations in model coefficients. A relatively new technique, geographically weighted regression (GWR) has been shown to greatly improve model performance compared to OLS in terms of higher R 2 and lower corrected Akaike information criterion (AIC C). GWR models have the potential to improve reliabilities of the identified relationships by reducing spatial autocorrelations and by accounting for local variations and spatial non-stationarity between dependent and independent variables. In this study, GWR was used to examine the relationship between land cover, rainfall and surface water habitat in 149 sub-catchments in a predominately agricultural region covering 2.6 million ha in southeast Australia. The application of the GWR models revealed that the relationships between land cover, rainfall and surface water habitat display significant spatial non-stationarity. GWR showed improvements over analogous OLS models in terms of higher R 2 and lower AIC C. The increased explanatory power of GWR was confirmed by the results of an approximate likelihood ratio test, which showed statistically significant improvements over analogous OLS models. The models suggest that the amount of surface water area in the landscape is related to anthropogenic drainage practices enhancing runoff to facilitate intensive agriculture and increased plantation forestry. However, with some key variables not present in our analysis, the strength of this relationship could not be qualified. GWR techniques have the potential to serve as a useful tool for environmental research and management across a broad range of scales for the investigation of spatially varying relationships. © 2011 Springer Science+Business Media B.V.

Asymmetry of information and the finance-growth nexus in emerging markets: empirical evidence using panel VECM analysis

  • Authors: Colombage, Sisira , Halabi, Abdel
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Journal of Developing Areas Vol. 46, no. 1 (2012), p. 133-146
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  • Description: This paper tests both the short and long term relationship between the real GDP, the equity amounts outstanding, the corporate bond amounts outstanding and bank credit to the private sector for five emerging markets. In particular, the finance-growth nexus is analysed with data collected from China, Indonesia, the Philippines, South Korea and Thailand between 1994 and 2009 using panel VECM analysis. The cointegration technique is then used to examine the long run behavior based on the assumption that all the variables involved have the same degree of integration and the error correction model (ECM) and the Wald test are employed to determine the direction of causality. The empirical results suggest the existence of a stable relationship in the direction from economic growth to financial market development that is consistent with the information asymmetry arguments for emerging markets. The findings have implications for financial and economic policy makers and enable these stakeholders to determine which sectors should be encouraged to achieve overall economic growth and development. The results are also useful to investors as they show the level of the intensity of information asymmetry on which these relationships might vary in both the short and long run.

Automatic modelling of cohesive crack propagation in concrete using polygon scaled boundary finite elements

  • Authors: Ooi, Ean Tat , Song, Chongmin , Tin-Loi, Francis , Yang, Zhenjun
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Engineering Fracture Mechanics Vol. 93, no. (2012), p. 13-33
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  • Description: An automatic cohesive crack propagation modelling methodology for quasi-brittle materials using polygon elements is presented. Each polygon is treated as a subdomain that is modelled by the scaled boundary finite element method (SBFEM). Generalised stress intensity factors (SIFs) based on matrix power function solutions of singular stress fields obtained from the SBFEM following standard finite element stress recovery procedures is used to evaluate the crack propagation criterion and determine the crack propagation direction. Interface elements model the fracture process zones and are automatically inserted into the polygon mesh as the crack propagates. A shadow domain procedure couples the polygons and interface elements. It computes the load-displacement response and crack propagation criterion, taking into account the cohesive tractions on the crack edges that are modelled as side-face tractions in the SBFEM. Cracks are propagated using a simple, yet flexible local remeshing procedure that can remesh any arbitrary polygon. Only minimal changes are made to the global mesh structure each time the remeshing algorithm is called. Five cohesive crack propagation benchmarks are modelled to validate the developed method and demonstrate its salient features. © 2012 Elsevier Ltd.

Bias in amputation research; impact of subjects missed from a prospective study

  • Authors: Fortington, Lauren , Geertzen, Jan , Bosmans, Joline , Dijkstra, Pieter
  • Date: 2012
  • Type: Text , Journal article
  • Relation: PLoS ONE Vol. 7, no. 8 (August 2012), p. e43629
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  • Description: For research findings to be generalized, a sample must be representative of the actual population of interest. Lower limb amputation is most frequently performed in older patients with vascular disease, a population that is often under-represented in research. The aim of this study was to explore the impact of selection bias by comparing characteristics from a sample included in a prospective study of phantom pain with the actual population who underwent amputation. Only 27% of all potential patients were referred during the first year of the prospective study. The referred patients were 8 years younger (p<0.001) and less likely to have had amputation because of a vascular condition, diabetes or infection (p = 0.003) than those not referred. There was also a significant difference in one year survival between the groups; 67% of referred patients survived compared with just 40% of non-referred patients (p = 0.004). The biased population in the phantom pain study may have resulted in an underestimation of phantom pain in the original study and subsequent protective factors should be considered within the context of the younger population reported. Selection bias is common in amputation research, and research methods to minimize its impact must be given greater attention.
  • Description: C1

Biomass energy holds big promise

Changes in vegetation over nine years after rehabilitating a linear feature in Australia's arid zone

  • Authors: Low, W. A. , McNally, A. , Davies, B. K. , Greenslade, Penelope
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Rangeland Journal Vol. 34, no. 4 (2012), p. 399-414
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  • Description: A 36-km road built in 1961 between Ayers Rock (Uluru) and the Olgas (Kata Tjuta), Northern Territory, Australia had seriously deteriorated by the 1980s. A newly aligned road, which was ecologically located and avoid sensitive Aboriginal sites, was completed early in 1991. The old road was rehabilitated by deep ripping, filling with imported sand and topsoil and by grading logs and windrows1 over the new surface. This paper reports on the effectiveness of the rehabilitation technique used in reinstating vegetation over 8 years and considers whether this rehabilitation aim was met. Plant colonisation and succession were monitored on 15 paired plots, one in the rehabilitated road and the other in the adjacent undisturbed habitat (with four exceptions) and also on the windrows. Sites at eight creek crossings and those subject to fire and rabbit activity were also monitored. Different landscape units responded in different ways to the rehabilitation. Herbaceous species from imported sand plain fill and top soil eventually dominated the road where they were introduced and were likely to persist in most areas because of local recruitment. The revegetation of the road has stabilised the old road surface as observed by the reduced erosion although succession did not always approach the reference site communities because of a greater resemblance to the Simpson Land System. Over the 8 years of monitoring considerable changes in vegetation occurred and are probably continuing. Only the road sites in the Simpson Land System approached the condition of the adjacent undisturbed vegetation because the vegetation of the other two land systems became closer to that of the Simpson Land System rather than to that of the surrounding vegetation. It is recommended that the introduced Buffel grass, known to alter landscape-level processes by reducing native herbaceous species and increasing risk of high intensity wildfire, which is most evident at creek crossings, should be controlled. Recommendations are made for improved management. © 2012 Australian Rangeland Society.
  • Description: 2003010572

Dense regeneration of floodplain Eucalyptus coolabah : Invasive scrub or passive restoration of an endangered woodland community?

  • Authors: Good, Megan , Price, Jodi , Clarke, Peter , Reid, Nick
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Rangeland Journal Vol. 34, no. 2 (2012), p. 219-233
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  • Description: Clearing of native vegetation and changes to disturbance regimes have resulted in dense regeneration of native trees and shrubs in parts of Australia. The conversion of open vegetation to dense woodlands may result in changes to the composition of plant communities and ecosystem function if structure, composition and function are tightly linked. Widespread clearing of the floodplain tree Eucalyptus coolabah subsp. coolabah (coolibah), in New South Wales, Australia, has led to state and federal listings of coolibah woodland as an endangered ecological community. Dense regeneration of coolibah in the mid 1970s, however, also resulted in its listing as an 'invasive native species' in NSW, meaning it can be legally cleared under certain conditions. Dense regeneration could be a novel state dissimilar to the threatened community or it could represent the next generation of coolibah woodlands and may contribute to passive restoration of heavily cleared landscapes. This study investigated if dense stands are distinct from remnant woodland by comparing floristic composition of the ground-storey community and top-soil properties of four coolibah vegetation states: derived grassland, derived degraded grassland, dense regeneration and remnant woodland. Ground-storey composition was found to overlap broadly among states regardless of tree density. Most species were common to all states, although dense regeneration contained characteristic woodland species that were absent from grasslands. The carbon:nitrogen ratio of the soil was significantly higher in dense regeneration and remnant woodland than in either of the grassland states, indicating that the woody states are broadly similar in terms of nutrient cycling. The study demonstrates that structurally different vegetation states (grasslands, woodlands and dense regeneration) are not associated with distinct plant communities. The results also suggest that grazing management has a more pronounced effect on ground-storey composition of plant communities than tree density and that well managed derived grasslands and dense regeneration are floristically similar to remnant woodlands. Since dense regeneration and remnant woodlands are not floristically distinct from one another, dense regeneration could contribute to the conservation of endangered coolibah woodlands in cleared agricultural landscapes. © Australian Rangeland Society 2012.