ORCID Profile
0000-0001-9239-4593
Current Organisation
Western Sydney University
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Ecological Impacts of Climate Change | Ecological Applications | Terrestrial Ecology | Ecosystem Function
Sparseland, Permanent Grassland and Arid Zone Soils | Ecosystem Adaptation to Climate Change | Ecosystem Assessment and Management of Forest and Woodlands Environments | Climate Change Mitigation Strategies | Native and Residual Pastures |
Publisher: Wiley
Date: 29-06-2021
Abstract: Free‐air carbon dioxide enrichment (FACE) experiments in terrestrial ecosystems have demonstrated ecological responses of key ecosystem processes to rising atmospheric carbon dioxide (CO 2 ). However, CO 2 fertilization responses in field conditions have seldom included methane (CH 4 ) and nitrous oxide (N 2 O), particularly in natural and mature forests, which are expected to have an important role in climate change mitigation. Herein, we aimed to capture the effect of elevated CO 2 (eCO 2 ambient vs. +150 ppm) on long‐term temporal dynamics of CH 4 and N 2 O fluxes, followed by identification of climo‐edaphic factors explaining feedback responses. To achieve this, continuous monitoring of greenhouse gas (GHG) fluxes using a manual chamber technique, over a 3‐year period was implemented in a mature dryland Eucalypt forest FACE (EucFACE) facility in Australia. The relationship between CH 4 and N 2 O fluxes with rainfall indices and soil properties was also explored since they directly impact the microbial communities in the soil responsible for CH 4 and N 2 O net emissions. Our results showed that in 3 years of eCO 2 treatment, the amount and frequency of rainfall predicted GHG emissions in this native forest. We also found a significant reduction in CH 4 sink (15%–25%) for some of the years as well as an overall treatment effect index reduction in N 2 O emissions under eCO 2 . Higher frequency of rain events with lower intensity led to highest CH 4 sink followed by lowest N 2 O emissions due to fewer wet–dry cycles. Of all the environmental variables included, soil moisture, rainfall and pH were the main predictors of net CH 4 and N 2 O emissions. Methane flux was also strongly influenced by soil texture. Our findings highlight the need to account for reduced forest CH 4 sink under eCO 2 in dryland ecosystems, which has implications for GHG budget predictions under future climate conditions. A free Plain Language Summary can be found within the Supporting Information of this article.
Publisher: Wiley
Date: 15-01-2014
Abstract: Loss of microbial ersity is considered a major threat because of its importance for ecosystem functions, but there is a lack of conclusive evidence that ersity itself is reduced under anthropogenic stress, and about the consequences of ersity loss. Heavy metals are one of the largest, widespread pollutant types globally, and these represent a significant environmental stressor for terrestrial microbial communities. Using combined metagenomics and functional assays, we show that the compositional and functional response of microbial communities to long-term heavy metal stress results in a significant loss of ersity. Our results indicate that even at a moderate loss of ersity, some key specialized functions (carried out by specific groups) may be compromised. Together with previous work, our data suggest disproportionate impact of contamination on microbes that carry out specialized, but essential, ecosystem functions. Based on these findings, we propose a conceptual framework to explicitly consider ersity of functions and microbial functional groups to test the relationship between bio ersity and soil functions.
Publisher: Elsevier BV
Date: 07-2015
Publisher: Elsevier BV
Date: 2016
Publisher: Elsevier BV
Date: 08-2009
Publisher: Wiley
Date: 09-05-2016
DOI: 10.1111/GCB.13268
Abstract: The response of terrestrial ecosystems to rising atmospheric CO2 concentration (Ca ), particularly under nutrient-limited conditions, is a major uncertainty in Earth System models. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment, recently established in a nutrient- and water-limited woodland presents a unique opportunity to address this uncertainty, but can best do so if key model uncertainties have been identified in advance. We applied seven vegetation models, which have previously been comprehensively assessed against earlier forest FACE experiments, to simulate a priori possible outcomes from EucFACE. Our goals were to provide quantitative projections against which to evaluate data as they are collected, and to identify key measurements that should be made in the experiment to allow discrimination among alternative model assumptions in a postexperiment model intercomparison. Simulated responses of annual net primary productivity (NPP) to elevated Ca ranged from 0.5 to 25% across models. The simulated reduction of NPP during a low-rainfall year also varied widely, from 24 to 70%. Key processes where assumptions caused disagreement among models included nutrient limitations to growth feedbacks to nutrient uptake autotrophic respiration and the impact of low soil moisture availability on plant processes. Knowledge of the causes of variation among models is now guiding data collection in the experiment, with the expectation that the experimental data can optimally inform future model improvements.
Publisher: Wiley
Date: 09-02-2016
DOI: 10.1111/GCB.13147
Abstract: Free-air CO2 enrichment (FACE) experiments have demonstrated increased plant productivity in response to elevated (e)CO2, with the magnitude of responses related to soil nutrient status. Whilst understanding nutrient constraints on productivity responses to eCO2 is crucial for predicting carbon uptake and storage, very little is known about how eCO2 affects nutrient cycling in phosphorus (P)-limited ecosystems. Our study investigates eCO2 effects on soil N and P dynamics at the EucFACE experiment in Western Sydney over an 18-month period. Three ambient and three eCO2 (+150 ppm) FACE rings were installed in a P-limited, mature Cumberland Plain Eucalyptus woodland. Levels of plant accessible nutrients, evaluated using ion exchange resins, were increased under eCO2, compared to ambient, for nitrate (+93%), ammonium (+12%) and phosphate (+54%). There was a strong seasonality to responses, particularly for phosphate, resulting in a relatively greater stimulation in available P, compared to N, under eCO2 in spring and summer. eCO2 was also associated with faster nutrient turnover rates in the first six months of the experiment, with higher N (+175%) and P (+211%) mineralization rates compared to ambient rings, although this difference did not persist. Seasonally dependant effects of eCO2 were seen for concentrations of dissolved organic carbon in soil solution (+31%), and there was also a reduction in bulk soil pH (-0.18 units) observed under eCO2. These results demonstrate that CO2 fertilization increases nutrient availability - particularly for phosphate - in P-limited soils, likely via increased plant belowground investment in labile carbon and associated enhancement of microbial turnover of organic matter and mobilization of chemically bound P. Early evidence suggests that there is the potential for the observed increases in P availability to support increased ecosystem C-accumulation under future predicted CO2 concentrations.
Publisher: Wiley
Date: 06-05-2023
DOI: 10.1002/SAE2.12043
Abstract: Plant microbiomes contribute directly to plant health and productivity, but mechanisms that underpin plant microbiome assembly in different compartments (e.g., root, leaf) are not fully understood. Identifying environmental and management factors that affect plant microbiome assembly is important to advance understanding of fundamental ecological processes, and to harness microbiome for improved primary productivity and environmental sustainability. Irrigation and fertilization are two common management practices in Australian tree plantations, but little is known about the effects of these treatments on soil, plant host and their microbiome. Here, we investigated the impact of decade‐long irrigation, fertilization and their combined application on soil, plant traits and microbiome of a Eucalyptus saligna plantation. Microbial profiling of bulk soil, rhizosphere, root and leaves was performed using licon sequencing 16S ribosomal DNA and internal transcribed spacer (ITS) markers for bacteria and fungi, respectively, along with measurements of soil properties and plant traits. The results indicated that both management practices significantly affected soil properties and soil and root microbiomes. Irrigation increased but fertilizer treatment reduced microbial alpha ersity. However, neither irrigation nor fertilizer treatment impacted the leaf microbiome. Our findings suggest that management practices impact soil edaphic factors, which in turn influence the below‐ground microbiome (soil and root), but the leaf microbiome remains unaffected. In addition, the leaf microbiome was distinct from soil and root microbiomes, and a source tracker analysis suggested that root and bulk soils only contributed to 53% and 10% operational taxonomic units of the leaf bacterial community, suggesting strong and sequential host selection of the leaf microbiome. In addition, management practices had a limited impact on leaf traits and, consequently, the leaf microbiome maintained its distinct composition. These findings provide mechanistic evidence for ecological processes that drive plant microbiome assembly and indicate that host selection plays a more important role than management practices in the leaf microbiome assembly.
Publisher: Wiley
Date: 23-07-2014
Abstract: Herbivory is an important modulator of plant bio ersity and productivity in grasslands, but our understanding of herbivore-induced changes on below-ground processes and communities is limited. Using a long-term (17 years) experimental site, we evaluated impacts of rabbit and invertebrate grazers on some soil functions involved in carbon cycling, microbial ersity, structure and functional composition. Both rabbit and invertebrate grazing impacted soil functions and microbial community structure. All functional community measures (functions, biogeochemical cycling genes, network association between different taxa) were more strongly affected by invertebrate grazers than rabbits. Furthermore, our results suggest that exclusion of invertebrate grazers decreases both microbial biomass and abundance of genes associated with key biogeochemical cycles, and could thus have long-term consequences for ecosystem functions. The mechanism behind these impacts are likely to be driven by both direct effects of grazing altering the pattern of nutrient inputs and by indirect effects through changes in plant species composition. However, we could not entirely discount that the pesticide used to exclude invertebrates may have affected some microbial community measures. Nevertheless, our work illustrates that human activity that affects grazing intensity may affect ecosystem functioning and sustainability, as regulated by multi-trophic interactions between above- and below-ground communities.
Publisher: Springer Science and Business Media LLC
Date: 03-02-2018
Publisher: American Geophysical Union (AGU)
Date: 03-2021
DOI: 10.1029/2020JG006221
Abstract: Understanding seasonal and diurnal dynamics of ecosystem respiration (R eco ) in forests is challenging, because R eco can only be measured directly during night‐time by eddy‐covariance flux towers. R eco is the sum of soil respiration (R soil ) and above‐ground respiration (in theory, R AG = R eco − R soil ). R soil can be measured day and night and can provide a check of consistency on R eco , as the difference in magnitude and time dynamic between R eco and R soil should be explained by R AG . We assessed the temporal patterns and climatic drivers of R soil and R eco in a mature eucalypt woodland, using continuous measurements (only at night for R eco ) at half‐hourly resolution over 4 years (2014–2017). Our data showed large seasonal and diurnal (overnight) variation of R eco , while R soil had a low diurnal litude and their difference (R eco − R soil, or R AG ) had a low seasonal litude. This result implies at first glance that seasonal variation of R eco was mainly influenced by R soil while its diurnal variation was mainly influenced by R AG . However, our analysis suggests that the night‐time R eco decline cannot realistically be explained by a decline of R AG . Chamber measurements of autotrophic components at half‐hourly time resolution are needed to quantify how much of the R eco decline overnight is due to declines in leaf or stem respiration, and how much is due to missing storage or advection, which may create a systematic bias in R eco measurements. Our findings emphasize the need for reconciling bottom‐up (via components measured with chambers) and direct estimates of R eco (via eddy‐covariance method).
Publisher: Wiley
Date: 07-11-2016
DOI: 10.1111/GCB.13109
Abstract: Projections of future climate are highly sensitive to uncertainties regarding carbon (C) uptake and storage by terrestrial ecosystems. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment was established to study the effects of elevated atmospheric CO2 concentrations (eCO2 ) on a native mature eucalypt woodland with low fertility soils in southeast Australia. In contrast to other FACE experiments, the concentration of CO2 at EucFACE was increased gradually in steps above ambient (+0, 30, 60, 90, 120, and 150 ppm CO2 above ambient of ~400 ppm), with each step lasting approximately 5 weeks. This provided a unique opportunity to study the short-term (weeks to months) response of C cycle flux components to eCO2 across a range of CO2 concentrations in an intact ecosystem. Soil CO2 efflux (i.e., soil respiration or Rsoil ) increased in response to initial enrichment (e.g., +30 and +60 ppm CO2 ) but did not continue to increase as the CO2 enrichment was stepped up to higher concentrations. Light-saturated photosynthesis of canopy leaves (Asat ) also showed similar stimulation by elevated CO2 at +60 ppm as at +150 ppm CO2 . The lack of significant effects of eCO2 on soil moisture, microbial biomass, or activity suggests that the increase in Rsoil likely reflected increased root and rhizosphere respiration rather than increased microbial decomposition of soil organic matter. This rapid increase in Rsoil suggests that under eCO2, additional photosynthate was produced, transported belowground, and respired. The consequences of this increased belowground activity and whether it is sustained through time in mature ecosystems under eCO2 are a priority for future research.
Publisher: Informa UK Limited
Date: 12-06-2013
DOI: 10.4161/BIOE.25320
Publisher: Elsevier BV
Date: 2016
Publisher: Oxford University Press (OUP)
Date: 09-2008
DOI: 10.1111/J.1574-6941.2008.00538.X
Abstract: The long-term impacts of Cu- and Zn-rich sewage sludge additions on the structure of the microbial community in a field under pasture were investigated using a combination of multiplex-terminal restriction fragment length polymorphism (M-TRFLP) and T-RFLP profiling approaches. Changes in the community structure of bacteria, fungi, archaea and actinobacteria were observed in soils that had previously received Cu- (50-200 mg kg(-1) soil) and Zn- (150-450 mg kg(-1) soil) rich sewage sludge additions. Changes in the structure of all microbial groups measured were observed at Cu and Zn rates below the current EU guidelines (135 mg kg(-1) Cu and 300 mg kg(-1) Zn). The response of the fungal community, and to a lesser extent the bacterial and archaeal community, to Cu was dose dependent. The fungal community also showed a dose-dependent response to Zn, which was not observed in the other microbial groups assessed. Redundancy analysis demonstrated that in idual terminal restriction fragments responded to both Cu and Zn and these may have potential as genetic markers of long-term metal effects in soil.
Publisher: Elsevier BV
Date: 2016
Publisher: Oxford University Press (OUP)
Date: 2010
DOI: 10.1111/J.1365-2672.2009.04416.X
Abstract: This study investigated the survival and transport of sewage sludge-borne pathogenic organisms in soils. Undisturbed soil cores were treated with Salmonella enterica ssp. enterica serovar Typhimurium-lux (STM-lux) and human adenovirus (HAdV)-spiked sewage sludge. Following an artificial rainfall event, these pathogens were analysed in the leachate and soil s led from different depths (0-5 cm, 5-10 cm and 10-20 cm) after 24 h, 1 and 2 months. Significantly more STM-lux and HAdV leached through the soil cores when sewage sludge was present. Significantly more STM-lux were found at all soil depths, at all time periods in the sewage sludge treatments, compared to the controls. The rate of decline of STM-lux in the controls was more rapid than in the sewage sludge treatments. Survival and transport of HAdV were minimal. The presence of sewage sludge can significantly influence the transport and survival of bacterial pathogens in soils, probably because of the presence of organic matter. Environmental contamination by virus is unlikely because of strong soil adsorption. This study suggests that groundwater contamination from vertical movement of pathogens is a potential risk and that it highlights the importance of the treatment requirements for biosolids prior to their application to land.
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.PEDOBI.2017.05.003
Abstract: The ecological interactions that occur in and with soil are of consequence in many ecosystems on the planet. These interactions provide numerous essential ecosystem services, and the sustainable management of soils has attracted increasing scientific and public attention. Although soil ecology emerged as an independent field of research many decades ago, and we have gained important insights into the functioning of soils, there still are fundamental aspects that need to be better understood to ensure that the ecosystem services that soils provide are not lost and that soils can be used in a sustainable way. In this perspectives paper, we highlight some of the major knowledge gaps that should be prioritized in soil ecological research. These research priorities were compiled based on an online survey of 32 editors of Pedobiologia - Journal of Soil Ecology. These editors work at universities and research centers in Europe, North America, Asia, and Australia.The questions were categorized into four themes: (1) soil bio ersity and biogeography, (2) interactions and the functioning of ecosystems, (3) global change and soil management, and (4) new directions. The respondents identified priorities that may be achievable in the near future, as well as several that are currently achievable but remain open. While some of the identified barriers to progress were technological in nature, many respondents cited a need for substantial leadership and goodwill among members of the soil ecology research community, including the need for multi-institutional partnerships, and had substantial concerns regarding the loss of taxonomic expertise.
Publisher: Wiley
Date: 24-10-2022
Abstract: Understanding the relative importance of soil microbial ersity, plants and nutrient management is crucial to implement an effective bioremediation approach to xenobiotics‐contaminated soils. To date, knowledge on the interactive effects of soil microbiome, plant and nutrient supply on influencing biodegradation potential of soils remains limited. In this study, we evaluated the in idual and interactive effects of soil initial bacterial ersity, nutrient amendments (organic and inorganic) and plant presence on the biodegradation rate of pyrene, a polycyclic aromatic hydrocarbon. Initial bacterial ersity had a strong positive impact on soil biodegradation potential, with soil harbouring higher bacterial ersity showing ~ 2 times higher degradation rates than soils with lower bacterial ersity. Both organic and inorganic nutrient amendments consistently improved the degradation rate in lower ersity soils and had negative (inorganic) to neutral (organic) effect in higher ersity soils. Interestingly, plant presence/type did not show any significant effect on the degradation rate in most of the treatments. Structural equation modelling demonstrated that initial bacterial ersity had a prominent role in driving pyrene biodegradation rates. We provide novel evidence that suggests that soil initial microbial ersity, and nutrient amendments should be explicitly considered in the design and employment of bioremediation management strategies for restoring natural habitats disturbed by organic pollutants.
Publisher: Elsevier BV
Date: 10-2011
Publisher: Springer Science and Business Media LLC
Date: 31-05-2018
Publisher: American Society for Microbiology
Date: 15-08-2007
DOI: 10.1128/AEM.00620-07
Abstract: We investigated the effect of afforestation and reforestation of pastures on methane oxidation and the methanotrophic communities in soils from three different New Zealand sites. Methane oxidation was measured in soils from two pine ( Pinus radiata ) forests and one shrubland (mainly Kunzea ericoides var. ericoides ) and three adjacent permanent pastures. The methane oxidation rate was consistently higher in the pine forest or shrubland soils than in the adjacent pasture soils. A combination of phospholipid fatty acid (PLFA) and stable isotope probing (SIP) analyses of these soils revealed that different methanotrophic communities were active in soils under the different vegetations. The C 18 PLFAs (signature of type II methanotrophs) predominated under pine and shrublands, and C 16 PLFAs (type I methanotrophs) predominated under pastures. Analysis of the methanotrophs by molecular methods revealed further differences in methanotrophic community structure under the different vegetation types. Cloning and sequencing and terminal-restriction fragment length polymorphism analysis of the particulate methane oxygenase gene ( pmoA ) from different s les confirmed the PLFA-SIP results that methanotrophic bacteria related to type II methanotrophs were dominant in pine forest and shrubland, and type I methanotrophs (related to Methylococcus capsulatus ) were dominant in all pasture soils. We report that afforestation and reforestation of pastures caused changes in methane oxidation by altering the community structure of methanotrophic bacteria in these soils.
Publisher: Elsevier BV
Date: 09-2016
Publisher: Wiley
Date: 09-05-2014
Abstract: Terrestrial arid and semi-arid ecosystems (drylands) constitute about 41% of the Earth's land surface and are predicted to experience increasing fluctuations in water and nitrogen availability. Mounting evidence has confirmed the significant importance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in nitrification, plant nitrogen availability and atmospheric N2 O emissions, but their responses to environmental perturbations in drylands remain largely unknown. Here we evaluate how the factorial combinations of irrigation and fertilization in forests and land-use change from grassland to forest affects the dynamics of AOA and AOB following a 6-year dryland field study. Potential nitrification rates and AOA and AOB abundances were significantly higher in the irrigated plots, accompanied by considerable changes in community compositions, but their responses to fertilization alone were not significant. DNA-stable isotope probing results showed increased (13) CO2 incorporation into the amoA gene of AOA, but not of AOB, in plots receiving water addition, coupled with significantly higher net mineralization and nitrification rates. High-throughput microarray analysis revealed that active AOA assemblages belonging to Nitrosopumilus and Nitrosotalea were increasingly labelled by (13) CO2 following irrigation. However, no obvious effects of land-use changes on nitrification rates or metabolic activity of AOA and AOB could be observed under dry conditions. We provide evidence that water addition had more important roles than nitrogen fertilization in influencing the autotrophic nitrification in dryland ecosystems, and AOA are increasingly involved in ammonia oxidation when dry soils become wetted.
Publisher: Elsevier BV
Date: 10-2007
Publisher: Cold Spring Harbor Laboratory
Date: 22-12-2020
DOI: 10.1101/2020.12.21.423155
Abstract: Shifts in the timing, intensity and/or frequency of climate extremes, such as severe drought and heatwaves, can generate sustained shifts in ecosystem function with important ecological and economic impacts for rangelands and managed pastures. The Pastures and Climate Extremes experiment (PACE) in Southeast Australia was designed to investigate the impacts of a severe winter/spring drought (60% rainfall reduction) and, for a subset of species, a factorial combination of drought and elevated temperature (ambient +3 °C) on pasture productivity. The experiment included nine common pasture and Australian rangeland species from three plant functional groups (C 3 grasses, C 4 grasses and legumes) planted in monoculture. Winter/spring drought resulted in productivity declines of 45% on average and up to 74% for the most affected species ( Digitaria eriantha ) during the 6-month treatment period, with eight of the nine species exhibiting significant yield reductions. Despite considerable variation in species’ sensitivity to drought, C 4 grasses were more strongly affected by this treatment than C 3 grasses or legumes. Warming also had negative effects on cool-season productivity, associated at least partially with exceedance of optimum growth temperatures in spring and indirect effects on soil water content. The combination of winter/spring drought and year-round warming resulted in the greatest yield reductions. We identified responses that were either additive such that there was only as significant warming effect under drought ( Festuca ), or less-than-additive, where there was no drought effect under warming ( Medicago ), compared to ambient plots. Results from this study highlight the sensitivity of erse pasture species to increases in winter and spring drought severity similar to those predicted for this region, and that anticipated benefits of cool-season warming are unlikely to be realised. Overall, the substantial negative impacts on productivity suggest that future, warmer, drier climates will result in shortfalls in cool-season forage availability, with profound implications for the livestock industry and natural grazer communities.
Publisher: Springer Science and Business Media LLC
Date: 06-03-2017
DOI: 10.1038/NCLIMATE3235
Publisher: Elsevier BV
Date: 03-2009
Publisher: Springer Science and Business Media LLC
Date: 26-05-2012
DOI: 10.1007/S00284-012-0148-X
Abstract: Challenges to the evidentiary value of morphometric determinations have led to a requirement for scientifically substantiated approaches to the forensic analysis of bite marks. Human teeth support genotypically distinctive populations of bacteria that could be exploited for forensic purposes. This study explored the feasibility of directly lifying bacterial DNA from bite marks for comparison with that from teeth. S les from self-inflicted experimental bite marks (n = 24) and human incisors were lified by PCR using primers specific for streptococcal 16S ribosomal DNA. Amplicon profiles (resolved by denaturing gradient gel electrophoresis) from bite mark s les aligned significantly more closely with profiles generated from the teeth responsible than with those from other teeth. Streptococcal licons were generated from dental s les applied to excised porcine skin for up to 48 h. These findings indicate that streptococcal DNA can be lified directly from bite marks, and have potential application in bite mark analysis.
Publisher: Wiley
Date: 19-06-2023
DOI: 10.1002/SAE2.12057
Abstract: Despite their potential benefits, it is not well understood how the application of biostimulants influences soil biological properties and their microbial communities in field conditions. In this study, we aimed to evaluate the impacts of biostimulants on soil biological and physicochemical properties relevant to soil health. To achieve this, we conducted a field study to investigate the effects of two types of commercially available biostimulants, Universal Natural Plant food (UNP) and Converte Seed Primer (CSP), on microbial activity, bacterial and fungal abundance, community structure and ersity, and soil chemical and physical properties across two depths (0–10 and 10–20 cm) from five sites under either wheat or pasture cultivation. Our findings suggest that application of UNP stimulated microbial activity by 40.1% in surface (0–10 cm) and 36.4% in deeper (10–20 cm) soil, but was dependant on site. Effects were generally greater in grasslands compared with arable soils. At sites where UNP stimulated microbial respiration, substrate‐induced respiration was also stimulated in surface soils and was associated with increased soil moisture content and higher total carbon and nitrogen. At the one site where UNP was combined with CSP, soil enzymes associated with carbon and nitrogen cycling were stimulated in UNP and UNP + CSP treatments. Total bacterial and fungal abundance and their alpha ersity did not respond to biostimulant treatment. However, microbial indicator communities were identified that responded positively to UNP and CSP addition across the two depths. Bacterial indicator species included Elsterales, Propionibacteriales, Solibacterales, Candatus, Reyranellales and Sphingomonadales , but differed between depths. For the fungal indicator species Filobasidiales (Basidiomycota) and Pleosporales (Ascomycota) were strong responders and common across both depths. Overall, our results suggest some positive effects of biostimulants on soil biological and physicochemical properties. Further long‐term studies should be conducted to evaluate the effects of biostimulants on crop yield and farm resilience.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.DRUDIS.2010.07.002
Abstract: Environmental microbes are a major source of drug discovery, and several microbial products (antibiotics, anti-tumour products, immunosuppressants and others) are used routinely for human therapies. Most of these products were obtained from cultivable (<1%) environmental microbes, and this means that the vast majority of microbes were not targeted for drug discovery. With the advent of new and emerging technologies, we are poised to harvest novel drugs from the so-called 'uncultivable' microbes. In this article, we propose how a multidisciplinary approach combining different technologies can expedite and revolutionize drug discovery from uncultivable microbes and examine the current limitations of technologies and strategies to overcome such limitations that might further expand the promise of drugs from environmental microbes.
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR13043
Abstract: This study sought to quantify the influence of ‘carbon farming’ practices on soil carbon stocks, in comparison with conventional grazing and cropping, in northern New South Wales. The study had two components: assessment of impacts of organic amendments on soil carbon and biological indicators in croplands on Vertosols of the Liverpool Plains and assessment of the impact of grazing management on soil carbon in Chromosols of the Northern Tablelands. The organic amendment sites identified for the survey had been treated with manures, composts, or microbial treatments, while the conventional management sites had received only chemical fertilisers. The rotational grazing sites had been managed so that grazing was restricted to short periods of several days, followed by long rest periods (generally several months) governed by pasture growth. These were compared with sites that were grazed continuously. No differences in total soil carbon stock, or soil carbon fractions, were observed between sites treated with organic amendments and those treated with chemical fertiliser. There was some evidence of increased soil carbon stock under rotational compared with continuous grazing, but the difference was not statistically significant. Similarly, double-stranded DNA (dsDNA) stocks were not significantly different in either of the management contrasts, but tended to show higher values in organic treatments and rotational grazing. The enzymatic activities of β-glucosidase and leucine-aminopeptidase were significantly higher in rotational than continuous grazing but statistically similar for the cropping site treatments. Relative abundance and community structure, measured on a subset of the cropping sites, showed a higher bacteria : fungi ratio and provided evidence that microbial process rates were significantly higher in chemically fertilised sites than organic amendment sites, suggesting enhanced mineralisation of organic matter under conventional management. The higher enzyme activity and indication of greater efficiency of microbial populations on carbon farming sites suggests a greater potential to build soil carbon under these practices. Further research is required to investigate whether the indicative trends observed reflect real effects of management.
Publisher: Wiley
Date: 14-09-2011
DOI: 10.1111/J.1556-4029.2010.01542.X
Abstract: DNA profiling of microbial communities has been proposed as a tool for forensic comparison of soils, but its potential to discriminate between soils from similar land use and/or geographic location has been largely unexplored. We tested the ability of terminal restriction fragment length polymorphism (T-RFLP) to discriminate between soils from 10 sites within the Greater Wellington region, New Zealand, based on their bacterial and fungal DNA profiles. Significant differences in bacterial and fungal communities between soils collected from all but one pair of sites were demonstrated. In some instances, specific terminal restriction fragments were associated with particular sites. Patch discrimination was evident within several sites, which could prove useful for site-specific matching (e.g., matching shoe/car tire print to an object). These results support the need for further understanding of the spatial distribution of soil microbial communities before DNA profiling of soil microbial communities can be applied to the forensic context.
Publisher: Springer Science and Business Media LLC
Date: 10-09-2020
DOI: 10.1007/S10533-020-00699-Y
Abstract: It is uncertain how the predicted further rise of atmospheric carbon dioxide (CO 2 ) concentration will affect plant nutrient availability in the future through indirect effects on the gross rates of nitrogen (N) mineralization (production of ammonium) and depolymerization (production of free amino acids) in soil. The response of soil nutrient availability to increasing atmospheric CO 2 is particularly important for nutrient poor ecosystems. Within a FACE (Free-Air Carbon dioxide Enrichment) experiment in a native, nutrient poor Eucalyptus woodland (EucFACE) with low soil organic matter (≤ 3%), our results suggested there was no shortage of N. Despite this, microbial N use efficiency was high (c. 90%). The free amino acid (FAA) pool had a fast turnover time (4 h) compared to that of ammonium (NH 4 + ) which was 11 h. Both NH 4 -N and FAA-N were important N pools however, protein depolymerization rate was three times faster than gross N mineralization rates, indicating that organic N is directly important in the internal ecosystem N cycle. Hence, the depolymerization was the major provider of plant available N, while the gross N mineralization rate was the constraining factor for inorganic N. After two years of elevated CO 2 , no major effects on the pools and rates of the soil N cycle were found in spring (November) or at the end of summer (March). The limited response of N pools or N transformation rates to elevated CO 2 suggest that N availability was not the limiting factor behind the lack of plant growth response to elevated CO 2 , previously observed at the site.
Publisher: Springer Science and Business Media LLC
Date: 12-09-2016
DOI: 10.1038/SREP33012
Abstract: Aggregates play a key role in protecting soil organic carbon (SOC) from microbial decomposition. The objectives of this study were to investigate the influence of pore geometry on the organic carbon decomposition rate and bacterial ersity in both macro- (250–2000 μm) and micro-aggregates (53–250 μm) using field s les. Four sites of contrasting land use on Alfisols (i.e. native pasture, crop asture rotation, woodland) were investigated. 3D Pore geometry of the micro-aggregates and macro-aggregates were examined by X-ray computed tomography (μCT). The occluded particulate organic carbon (oPOC) of aggregates was measured by size and density fractionation methods. Micro-aggregates had 54% less μCT observed porosity but 64% more oPOC compared with macro-aggregates. In addition, the pore connectivity in micro-aggregates was lower than macro-aggregates. Despite both lower μCT observed porosity and pore connectivity in micro-aggregates, the organic carbon decomposition rate constant (Ksoc) was similar in both aggregate size ranges. Structural equation modelling showed a strong positive relationship of the concentration of oPOC with bacterial ersity in aggregates. We use these findings to propose a conceptual model that illustrates the dynamic links between substrate, bacterial ersity, and pore geometry that suggests a structural explanation for differences in bacterial ersity across aggregate sizes.
Publisher: Wiley
Date: 24-07-2017
Publisher: Elsevier BV
Date: 03-2016
Publisher: Wiley
Date: 06-05-2021
DOI: 10.1002/EAP.2325
Abstract: Soil microbial community functions are essential indicators of ecosystem multifunctionality in managed land‐use systems. Going forward, the development of adaptation strategies and predictive models under future climate scenarios will require a better understanding of how both land‐use and climate disturbances influence soil microbial functions over time. Between March and November 2018, we assessed the effects of climate change on the magnitude and temporal stability of soil basal respiration, soil microbial biomass and soil functional ersity across a range of land‐use types and intensities in a large‐scale field experiment. Soils were s led from five common land‐use types including conventional and organic croplands, intensive and extensive meadows, and extensive pastures, under ambient and projected future climate conditions (reduced summer precipitation and increased temperature) at the Global Change Experimental Facility (GCEF) in Bad Lauchstädt, Germany. Land‐use and climate treatment interaction effects were significant in September, a month when precipitation levels slightly rebounded following a period of drought in central Germany: compared to ambient climate, in future climate treatments, basal respiration declined in pastures and increased in intensive meadows, functional ersity declined in pastures and croplands, and respiration‐to‐biomass ratio increased in intensive and extensive meadows. Low rainfall between May and August likely strengthened soil microbial responses toward the future climate treatment in September. Although microbial biomass showed declining levels in extensive meadows and pastures under future climate treatments, overall, microbial function magnitudes were higher in these land‐use types compared to croplands, indicating that improved management practices could sustain high microbial ecosystem functioning in future climates. In contrast to our hypothesis that more disturbed land‐use systems would have destabilized microbial functions, intensive meadows and organic croplands showed stabilized soil microbial biomass compared to all other land‐use types, suggesting that temporal stability, in addition to magnitude‐based measurements, may be useful for revealing context‐dependent effects on soil ecosystem functioning.
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.TREE.2019.07.011
Abstract: Our knowledge of host-associated microorganisms and their role in host functions is rapidly evolving. Stress-affected plants assemble beneficial microbes in their rhizosphere to maximize survival and growth. Similarly, insects have gut microbiomes that extend their functional repertoire in fighting stress. A strong microbial linkage between soil, plants, and pollinators is emerging and this can influence pollination services and overall ecosystem health. Yet, the nature of microbial interactions between different ecosystem components remains poorly understood. Here we highlight the acquisition pathways of beneficial microbes and their functions in protecting hosts against stress. By adopting a new 'eco-holobiont' approach, which explicitly incorporates biotic feedbacks, we can significantly expand our ecological understanding and better develop sustainable environmental management.
Publisher: Elsevier BV
Date: 08-2021
Start Date: 12-2022
End Date: 11-2025
Amount: $499,786.00
Funder: Australian Research Council
View Funded ActivityStart Date: 12-2022
End Date: 12-2026
Amount: $368,981.00
Funder: Australian Research Council
View Funded Activity