ORCID Profile
0000-0003-2514-9744
Current Organisation
University of Melbourne
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Forestry Management and Environment | Ecological Impacts of Climate Change | Terrestrial Ecology | Environmental Science and Management | Psychology | Ecological Applications | Conservation and Biodiversity | Social and Community Psychology
Ecosystem Assessment and Management of Forest and Woodlands Environments | Forest and Woodlands Flora, Fauna and Biodiversity | Ecosystem Adaptation to Climate Change | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Environmental Ethics | Native Forests |
Publisher: Springer Science and Business Media LLC
Date: 30-10-2014
DOI: 10.1007/S00484-013-0756-6
Abstract: Growth is one of the most important phenological cycles in a plant's life. Higher growth rates increase the competitive ability, survival and recruitment and can provide a measure of a plant's adaptive capacity to climate variability and change. This study identified the growth relationship of six Eucalyptus species to variations in temperature, soil moisture availability, photoperiod length and air humidity over 12 months. The six species represent two naturally co-occurring groups of three species each representing warm-dry and the cool-moist sclerophyll forests, respectively. Warm-dry eucalypts were found to be more tolerant of higher temperatures and lower air humidity than the cool-moist eucalypts. Within groups, species-specific responses were detected with Eucalyptus microcarpa having the widest phenological niche of the warm-dry species, exhibiting greater resistance to high temperature and lower air humidity. Temperature dependent photoperiodic responses were exhibited by all the species except Eucalyptus tricarpa and Eucalyptus sieberi, which were able to maintain growth as photoperiod shortened but temperature requirements were fulfilled. Eucalyptus obliqua exhibited a flexible growth rate and tolerance to moisture limitation which enables it to maintain its growth rate as water availability changes. The wider temperature niche exhibited by E. sieberi compared with E. obliqua and Eucalyptus radiata may improve its competitive ability over these species where winters are warm and moisture does not limit growth. With climate change expected to result in warmer and drier conditions in south-east Australia, the findings of this study suggest all cool-moist species will likely suffer negative effects on growth while the warm-dry species may still maintain current growth rates. Our findings highlight that climate driven shifts in growth phenology will likely occur as climate changes and this may facilitate changes in tree communities by altering inter-specific competition.
Publisher: Informa UK Limited
Date: 22-05-2007
Publisher: Copernicus GmbH
Date: 30-03-2016
Abstract: Abstract. Management of temperate forests has the potential to increase carbon sinks and mitigate climate change. However, those opportunities may be confounded by negative climate change impacts. We therefore need a better understanding of climate change alterations to temperate forest carbon dynamics before developing mitigation strategies. The purpose of this project was to investigate the interactions of species composition, fire, management, and climate change in the Copper–Pine Creek valley, a temperate coniferous forest with a wide range of growing conditions. To do so, we used the LANDIS-II modelling framework including the new Forest Carbon Succession extension to simulate forest ecosystems under four different productivity scenarios, with and without climate change effects, until 2050. Significantly, the new extension allowed us to calculate the net sector productivity, a carbon accounting metric that integrates aboveground and belowground carbon dynamics, disturbances, and the eventual fate of forest products. The model output was validated against literature values. The results implied that the species optimum growing conditions relative to current and future conditions strongly influenced future carbon dynamics. Warmer growing conditions led to increased carbon sinks and storage in the colder and wetter ecoregions but not necessarily in the others. Climate change impacts varied among species and site conditions, and this indicates that both of these components need to be taken into account when considering climate change mitigation activities and adaptive management. The introduction of a new carbon indicator, net sector productivity, promises to be useful in assessing management effectiveness and mitigation activities.
Publisher: Cambridge University Press (CUP)
Date: 05-11-2018
DOI: 10.1017/RDC.2018.119
Abstract: Tree ferns are slow-growing and long-lived components of temperate forests however, these characteristics make determining size-age and population dynamics through mensuration approaches problematic while dendroecological approaches cannot be used. In this study, we use radiocarbon ( 14 C) dating of Cyathea australis and Dicksonia antarctica to (1) determine their age-to-size relationships, (2) reconstruct the age distribution of tree fern species, and (3) test if predicted ages align with the ages of the co-occurring tree community and observed disturbance history. We used the best age-size models to reconstruct the population structure of tree ferns s led in five paired rainforest and old-growth eucalypt stands and compared these to the age structure of co-occurring tree species. The species had similar growth allometry however, C. australis grew four times faster than D. antarctica . The age class structures of tree ferns were congruent with the associated tree species and reflected known fire history and snowfall events in the region. Tree fern abundance increased with increasing time-since-fire and post canopy disturbance. The study demonstrates that 14 C dating of tree ferns provides a means of investigating tree fern demographics and the role of disturbance in shaping their population structure in forests of southeast Australia.
Publisher: Elsevier BV
Date: 11-2023
Publisher: Elsevier BV
Date: 10-2017
Publisher: MDPI AG
Date: 28-10-2022
DOI: 10.3390/SU142114050
Abstract: Indirect impacts of Human Wildlife Conflict (HWC) are largely ignored, poorly understood, and scantly reported in the literature on HWC. Subsistence farmers in the Himalayan kingdom of Bhutan experience an increasing intensification of HWC impacts. Working across four districts representing different geographic regions of the country, we explored the perceived indirect impacts of HWC and how they affect the well-being and happiness of subsistence farmers using qualitative interviews (n = 48) and focus group discussions (n = 8). We conducted a qualitative thematic analysis. Based on respondent’s explanations, we coded the data according to effect of indirect impacts on human, social, financial, physical, natural, and psychological capitals. Mental distress, constant worries about food insecurity, fears for physical safety, frustration of movement restriction due to fear of being attack by wildlife, feelings of economic insecurity and anger over loss of crop and livestock due to wild predators affect the psychological health and well-being of research participants. Vulnerabilities related to gender and wealth status further deepen the effect of indirect impacts. Policies designed to address HWC should incorporate an understanding of the effects of indirect impacts of HWC and should focus on female-headed and poor households to reduce the negative effects of wildlife impacts.
Publisher: Springer Science and Business Media LLC
Date: 22-06-2012
Publisher: Wiley
Date: 12-08-2015
DOI: 10.1111/AEC.12183
Publisher: Oxford University Press (OUP)
Date: 03-04-2023
Abstract: The Search for Extra-Terrestrial Intelligence (SETI) has been conducted for over 60 yr, yet no technosignatures have been identified. Previous studies have focused on stars in our Galaxy, with few searches in the extragalactic Universe despite a larger volume being available. Civilizations capable of harvesting energy from a star or a galaxy are classified as KII or KIII on the Kardashev scale, respectively. Technosignatures from such advanced civilizations would be extremely luminous and detectable by current radio telescopes, even from distant galaxies. To explore the frontier of extragalactic SETI, we investigate the likely prevalence of extragalactic civilizations possessing a radio transmitter, known as the transmitter rate, based on observational results from the Breakthrough Listen (BL) observations. We calculated the transmitter rate by considering the background galaxies in the field of view of target stars in BL observations. We used a statistical method to derive the total mass of stars in those background galaxies from a galaxy stellar mass function. Our statistical method suggests that less than one in hundreds of trillions of extragalactic civilizations within 969 Mpc possess a radio transmitter above 7.7 × 1026 W of power, assuming one civilization per one-solar-mass stellar system. Additionally, we cross-matched the BL survey fields with the WISE × SuperCOSMOS Photometric Redshift Catalogue and compared with the statistical method. Our result sets the strictest limits to date on the transmitter rate at such high-power levels, emphasizing the high efficiency of searching for radio transmitters in galaxies and the rarity of technologically advanced civilizations in our Universe.
Publisher: California Digital Library (CDL)
Date: 29-10-2021
DOI: 10.31223/X51W5K
Abstract: Soil moisture is a key limiting factor of plant productivity in boreal and montane regions, producing additional climate feedbacks through evaporation, regeneration, mortality, and respiration. Understory solar irradiation – the primary driver of surface temperature and evaporative demand – remains poorly represented in vegetation models due to a lack of 3-D canopy geometry. Existing models are further unable to represent processes lacking sufficient parameterization and/or knowledge, with no land model to date utilizing machine learning (ML) to represent vegetation processes. Here, we developed the first hybrid forest ecosystem model using ML (ML-FEM), a specific case of hybrid AI land model (a concept also invented here). In this approach, ML models are trained and validated with a ground-truth dataset, whether observations or high-fidelity simulations, before being applied to vegetation model parameters for inference, internally or externally to the model. Using this approach, we simulated annual understory global solar irradiation (Iu) across 25.2 Mha in southwestern Canada at 1-ha resolution under historical climate and fire scenarios. In cross-validation, we found that linear and ML regression models performed comparably well in the prediction of angular canopy cover (ACC), due to the linearity of its relationship to predictors (linear R2 = 0.938, RMSE = 0.079 ML R2 = 0.939, RMSE = 0.074). Reduced area burned, increased ignitions, and reduced regeneration potential for recent periods resulted in stable or reduced Iu. This suggests that diminished disturbance may reduce Iu through forest aging, masking latent regeneration decline. Only in the most extreme and unconstrained scenarios did Iu increase. In these experiments, conducted in late 2015, we demonstrated an entirely new class of hybrid models that we anticipated to be of vital importance to understanding and representing pattern-based processes in Earth system models.
Publisher: Oxford University Press (OUP)
Date: 21-09-2018
Publisher: Springer Science and Business Media LLC
Date: 26-03-2008
Publisher: Wiley
Date: 12-2021
DOI: 10.1002/ECE3.8428
Abstract: Herbivore foraging decisions are closely related to plant nutritional quality. For arboreal folivores with specialized diets, such as the vulnerable greater glider ( Petauroides volans ), the abundance of suitable forage trees can influence habitat suitability and species occurrence. The ability to model and map foliar nitrogen would therefore enhance our understanding of folivore habitat use at finer scales. We tested whether high‐resolution multispectral imagery, collected by a lightweight and low‐cost commercial unoccupied aerial vehicle (UAV), could be used to predict total and digestible foliar nitrogen (N and digN) at the tree canopy level and forest stand‐scale from leaf‐scale chemistry measurements across a gradient of mixed‐species Eucalyptus forests in southeastern Australia. We surveyed temperate Eucalyptus forests across an elevational and topographic gradient from sea level to high elevation (50–1200 m a.s.l.) for forest structure, leaf chemistry, and greater glider occurrence. Using measures of multispectral leaf reflectance and spectral indices, we estimated N and digN and mapped N and favorable feeding habitat using machine learning algorithms. Our surveys covered 17 Eucalyptus species ranging in foliar N from 0.63% to 1.92% dry matter (DM) and digN from 0.45% to 1.73% DM. Both multispectral leaf reflectance and spectral indices were strong predictors for N and digN in model cross‐validation. At the tree level, 79% of variability between observed and predicted measures of nitrogen was explained. A spatial supervised classification model correctly identified 80% of canopy pixels associated with high N concentrations (≥1% DM). We developed a successful method for estimating foliar nitrogen of a range of temperate Eucalyptus species using UAV multispectral imagery at the tree canopy level and stand scale. The ability to spatially quantify feeding habitat using UAV imagery allows remote assessments of greater glider habitat at a scale relevant to support ground surveys, management, and conservation for the vulnerable greater glider across southeastern Australia.
Publisher: Springer Science and Business Media LLC
Date: 27-02-2023
Publisher: Oxford University Press (OUP)
Date: 29-04-2023
Abstract: We report the detection of ammonia masers in the non-metastable (6, 3), (7, 5), and (6, 5) transitions the latter being the first unambiguous maser detection of that transition ever made. Our observations include the first very long baseline interferometry detection of ammonia maser emission, which allowed effective constraining of the (6, 5) maser brightness temperature. The masers were detected towards G 358.931−0.030, a site of 6.7-GHz class II methanol maser emission that was recently reported to be undergoing a period of flaring activity. These ammonia masers appear to be flaring contemporaneously with the class II methanol masers during the accretion burst event of G 358.931−0.030. This newly detected site of ammonia maser emission is only the 12th such site discovered in the Milky Way. We also report the results of an investigation into the maser pumping conditions, for all three detected masing transitions, through radiative transfer calculations constrained by our observational data. These calculations support the hypothesis that the ammonia (6, 5) maser transition is excited through high colour temperature infrared emission, with the (6, 5) and (7, 5) transition line ratio implying dust temperatures & K. Additionally, we detect significant linearly polarized emission from the ammonia (6, 3) maser line. Alongside our observational and radiative transfer calculation results, we also report newly derived rest frequencies for the ammonia (6, 3) and (6, 5) transitions.
Publisher: Wiley
Date: 07-2018
DOI: 10.1111/JVS.12649
Publisher: Elsevier BV
Date: 2013
Publisher: Springer Science and Business Media LLC
Date: 20-11-2015
DOI: 10.1007/S00484-014-0935-0
Abstract: Germination is considered one of the important phenological stages that are influenced by environmental factors, with timing and abundance determining plant establishment and recruitment. This study investigates the influence of temperature, soil moisture and light on the germination phenology of six Eucalyptus species from two co-occurring groups of three species representing warm-dry and cool-moist sclerophyll forests. Data from germination experiments were used to calibrate the germination module of the mechanistic model TACA-GEM, to evaluate germination phenology under a range of climate change scenarios. With the exception of E. polyanthemos, the optimal niche for all species was characterised by cool-moist stratification, low light, cool temperatures and high soil moisture. Model results indicated that of the warm-dry species, Eucalyptus microcarpa exhibited greater germination and establishment under projected changes of warmer drier conditions than its co-occurring species Eucalyptus polyanthemos and Eucalyptus tricarpa which suggests that E. microcarpa could maintain its current distribution under a warmer and drier climate in southeastern Australia. Among the cool-moist species, Eucalyptus radiata was the only species that established under projected climate change of the 2080s but at such a low probability that its persistence compared to Eucalyptus obliqua and Eucalyptus sieberi cannot be posited. For all cool-moist species, germination did not benefit from the phenological shifts they displayed. This study successfully demonstrated environmental effects on germination phenology and how a shift in climate can influence the timing and success of recruitment.
Publisher: American Geophysical Union (AGU)
Date: 30-12-2021
DOI: 10.1029/2020WR029409
Abstract: Links between climate variability modes, rainfall, and streamflow are important for understanding the trajectories of change and dynamics in water availability. In this study, we examined the influence of the El Nino Southern Oscillation, Indian Ocean Dipole, Southern Annular Mode, and Interdecadal Pacific Oscillation modes on interannual variations in rainfall and streamflow in four hydroclimate regions. We also explored the link between climate variability modes and extreme rainfall and streamflow years. Climate mode indices, rainfall, and streamflow data from 1975 to 2018 were analyzed for 92 predominately forested catchments located across temperate Australia. Climate modes had ergent influences on streamflow and rainfall between and within regions. Across temperate Australia, a higher proportion of interannual variation in rainfall was explained by climate modes than for streamflow, indicating factors other than atmosphere‐ocean phenomena are important in determining interannual streamflow variability. Extremes in rainfall and streamflow across regions were related to the co‐occurrence of climate modes, with a stronger relationship between teleconnections and low rainfall/streamflow years than high rainfall/streamflow years. The study provides new insights into the regional drivers of hydrological extremes and consolidates our understanding of the role of teleconnections on water availability in the temperate zone of Australia.
Publisher: Wiley
Date: 14-03-2017
DOI: 10.1002/JOC.5045
Publisher: Oxford University Press (OUP)
Date: 13-09-2019
Abstract: We report the detection of new 12.178, 12.229, 20.347, and 23.121 GHz methanol masers in the massive star-forming region G358.93−0.03, which are flaring on similarly short time-scales (days) as the 6.668 GHz methanol masers also associated with this source. The brightest 12.178 GHz channel increased by a factor of over 700 in just 50 d. The masers found in the 12.229 and 20.347 GHz methanol transitions are the first ever reported and this is only the fourth object to exhibit associated 23.121 GHz methanol masers. The 12.178 GHz methanol maser emission appears to have a higher flux density than that of the 6.668 GHz emission, which is unusual. No associated near-infrared flare counterpart was found, suggesting that the energy source of the flare is deeply embedded.
Publisher: Wiley
Date: 09-02-2016
DOI: 10.1111/GCB.13177
Abstract: The surge in global efforts to understand the causes and consequences of drought on forest ecosystems has tended to focus on specific impacts such as mortality. We propose an ecoclimatic framework that takes a broader view of the ecological relevance of water deficits, linking elements of exposure and resilience to cumulative impacts on a range of ecosystem processes. This ecoclimatic framework is underpinned by two hypotheses: (i) exposure to water deficit can be represented probabilistically and used to estimate exposure thresholds across different vegetation types or ecosystems and (ii) the cumulative impact of a series of water deficit events is defined by attributes governing the resistance and recovery of the affected processes. We present case studies comprising Pinus edulis and Eucalyptus globulus, tree species with contrasting ecological strategies, which demonstrate how links between exposure and resilience can be examined within our proposed framework. These ex les reveal how climatic thresholds can be defined along a continuum of vegetation functional responses to water deficit regimes. The strength of this framework lies in identifying climatic thresholds on vegetation function in the absence of more complete mechanistic understanding, thereby guiding the formulation, application and benchmarking of more detailed modelling.
Publisher: Wiley
Date: 29-12-2018
Publisher: Wiley
Date: 24-10-2021
DOI: 10.1111/CSP2.566
Abstract: Wildlife can persist in a range of landscape configurations, but population densities can vary due to resource availability. Resources and environmental conditions shaping habitat suitability may be spatially dispersed or clumped, which can drive habitat availability. We explored how spatial configuration and aggregation of favorable feeding resources and climatic conditions affect populations of the greater glider ( Petauroides volans ), an arboreal marsupial in southeast Australia, vulnerable to climate change and disturbances. We hypothesized home‐range functionality from literature and field observations and used a generalized spatial framework based on neutral landscape models to test how spatial aggregation influences home‐range sizes and population structure. At the landscape scale, any decrease in climatic suitability also decreased potential population density, independent of the initial spatial configuration of the feeding landscape. At the stand scale however, the spatial configuration of feeding habitat drove population density. Dispersed resources required increased home‐range sizes for in idual greater gliders to obtain feeding resources and resulted in smaller populations. Clumped resources supported larger populations, even when only small fractions of the stand contained feeding habitat. Disturbances to these resources could either retain populations or lead to extinction, depending on spatial aggregation and disturbance intensity. Increasingly severe dispersed disturbances caused potential home ranges to disappear more rapidly and remaining home ranges to become larger and contain less feeding habitat. The ability of greater gliders to establish populations and persist under disturbance was therefore highly dependent on the spatial aggregation of habitat resources and the type and severity of disturbance. Changes in climate act at a different scale and may override favorable habitat conditions at the stand level. Our results have implications for the conservation and retention of critical feeding habitat for greater gliders and provide insights into important factors to ensure population persistence under climate change and forest management.
Publisher: MDPI AG
Date: 07-01-2019
DOI: 10.3390/RS11010093
Abstract: Modern approaches to predictive ecosystem mapping (PEM) have not thoroughly explored the use of ‘characteristic’ gradients, which describe vegetation structure (e.g., light detection and ranging (lidar)-derived structural profiles). In this study, we apply a PEM approach by classifying the dominant stand types within the Central Highlands region of south-eastern Australia using both lidar and species distribution models (SDMs). Similarity percentages analysis (SIMPER) was applied to comprehensive floristic surveys to identify five species which best separated stand types. The predicted distributions of these species, modelled using random forests with environmental (i.e., climate, topography) and optical characteristic gradients (Landsat-derived seasonal fractional cover), provided an ecological basis for refining stand type classifications based only on lidar-derived structural profiles. The resulting PEM model represents the first continuous distribution map of stand types across the study region that delineates ecotone stands, which are seral communities comprised of species typical of both rainforest and eucalypt forests. The spatial variability of vegetation structure incorporated into the PEM model suggests that many stand types are not as continuous in cover as represented by current ecological vegetation class distributions that describe the region. Improved PEM models can facilitate sustainable forest management, enhanced forest monitoring, and informed decision making at landscape scales.
Publisher: Elsevier BV
Date: 12-2015
Publisher: Wiley
Date: 2020
DOI: 10.1002/BES2.1807
Publisher: MDPI AG
Date: 05-06-2023
DOI: 10.3390/F14061166
Abstract: A fundamental requirement of sustainable forest management is that stands are adequately regenerated after harvesting. To date, most research has focused on the regeneration of the dominant timber species and to a lesser degree on plant communities. Few studies have explored the impact of the regeneration success of dominant tree species on plant community composition and ersity. In this study, we quantified the influence of variability in tree density and climatic and edaphic factors on plant species ersity in montane regrowth forests dominated by Eucalyptus regnans in the Central Highlands of Victoria in southeastern Australia. We found that Acacia density shaped plant bio ersity more than Eucalyptus density. Edaphic factors, particularly soil nutrition and moisture availability, played a significant role in shaping species turnover and occurrence. Our findings suggest that the density of Acacia is a key biotic filter that influences the occurrence of many understorey plant species and shapes plant community turnover. This should be considered when assessing the impacts of both natural and anthropogenic disturbances on plant bio ersity in the montane forests of southeastern Australia.
Publisher: California Digital Library (CDL)
Date: 29-10-2021
DOI: 10.31223/X55P8W
Abstract: The population structure of forests is shaped by balancing the opposing forces of regeneration and mortality, each of which influence C turnover rates and are sensitive to climate. Regeneration underlies the migrational potential of forests to climatic change and remains underserved in modeling studies. Our objective was to test the hypothesis that warming may reduce tree regeneration rates while lifying fire regimes, producing forest loss. Absent sites within dispersal limits, trees may fail to track the velocity of warming, producing a decline in forested area. Long-term implications include changes to biogeochemical and energetic balances, species composition, and evolutionary trajectories. We performed hybrid model simulations to assess the resilience of forests to past-century conditions over the next fifty years in western Canada. We conducted simulations at a species-level taxonomic resolution to capture genotypic henotypic variability in response to climate. A recent shift toward small, frequent, human-caused fires and warming-reduced regeneration diminished species migration potential. The simulated rate of forest migration lagged behind temperature equilibria by 319 m yr-1. Understanding species migrational potential is particularly critical for northern forests, which have warmed at a rate twice the global mean. Our findings highlight the effect of diminished regeneration due to climatic change, a process neglected in current global-scale terrestrial biosphere models used in climate studies. We suggest that future terrestrial biosphere model studies incorporate these demographic rates in their findings on global change, as they carry substantial climatic and evolutionary implications.
Publisher: Springer Science and Business Media LLC
Date: 17-07-2017
Publisher: Inter-Research Science Center
Date: 12-01-2016
DOI: 10.3354/CR01356
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 05-2017
Publisher: Wiley
Date: 22-10-2016
DOI: 10.1111/JVS.12468
Publisher: Elsevier BV
Date: 08-2005
Publisher: American Astronomical Society
Date: 21-02-2017
Publisher: Oxford University Press (OUP)
Date: 30-09-2015
DOI: 10.5849/JOF.14-086
Publisher: Public Library of Science (PLoS)
Date: 17-11-2014
Publisher: MDPI AG
Date: 10-09-2018
DOI: 10.3390/F9090554
Abstract: Ecosystem services (ES) are critical to human well-being, especially in developing countries. Improved understanding of the status of ES is required to help people improve their quality of life. The status of ES is largely unknown in many regions of Nepal. This study was carried out in one of Nepal’s bio ersity hotspots, the Panchase Mountain Ecological region (PMER), to identify, prioritize and map the major ES in the region. Primary data for the study were collected through key informant interviews, focus group discussions, a transect walk, and field observations. Similarly, secondary data were obtained from published and unpublished reports and satellite images of the study area. The data were analyzed both qualitatively and quantitatively. Thirty-seven ES were identified from the study landscape. Among them, nine were provisioning services, thirteen regulating services, nine cultural services, and six supporting services. Interestingly, the prioritization of ES among stakeholders differed on the basis of their background, particular features of their landscape, professional engagement, and in idual interests. For instance, forest users prioritized provisioning services for their daily needs whereas forest managers prioritized regulating and cultural services for overall ecosystem management and aesthetic values. Mapping of the ES from the landscape for 1995 and 2015 identified that forest area and associated ES have likely increased, especially in the upland regions, while agricultural land and their associated ES have decreased. The study can be used as a reference by planners and policy makers in managing ES in the PMER to increase synergies and reduce trade-off among various services.
Publisher: Oxford University Press (OUP)
Date: 05-09-2022
DOI: 10.1093/PASJ/PSAC067
Abstract: In 2019 September, a sudden flare of the 6.7 GHz methanol maser was observed toward the high-mass young stellar object (HMYSO) G24.33+0.14. This may represent the fourth detection of a transient mass accretion event in an HMYSO after S255IR NIRS3, NGC 6334I-MM1, and G358.93−0.03-MM1. G24.33+0.14 is unique among these sources as it clearly shows a repeating flare with an 8 yr interval. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we observed the millimeter continuum and molecular lines toward G24.33+0.14 in the pre-flare phase in 2016 August (ALMA Cycle 3) and the mid-flare phase in 2019 September (ALMA Cycle 6). We identified three continuum sources in G24.33+0.14, and the brightest source, C1, which is closely associated with the 6.7 GHz maser emission, shows only a marginal increase in flux density with a flux ratio (Cycle 6$/$Cycle 3) of 1.16 ± 0.01, considering an additional absolute flux calibration uncertainty of $10\\%$. We identified 26 transitions from 13 molecular species other than methanol, and they exhibit similar levels of flux differences with an average flux ratio of 1.12 ± 0.15. In contrast, eight methanol lines observed in Cycle 6 are brighter than those in Cycle 3 with an average flux ratio of 1.23 ± 0.13, and the higher excitation lines tend to show a larger flux increase. If this systematic increasing trend is real, it would suggest radiative heating close to the central HMYSO due to an accretion event which could expand the size of the emission region and/or change the excitation conditions. Given the low brightness temperatures and small flux changes, most of the methanol emission is likely to be predominantly thermal, except for the 229.759 GHz (8−1–70 E) line known as a class I methanol maser. The flux change in the millimeter continuum of G24.33+0.14 is smaller than in S255IR NIRS3 and NGC 6334I-MM1 but is comparable with that in G358.93−0.03-MM1, suggesting different amounts of accreted mass in these events.
Publisher: Elsevier BV
Date: 08-2014
Publisher: Elsevier BV
Date: 12-2018
Publisher: Springer Science and Business Media LLC
Date: 20-04-2016
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.JENVMAN.2013.02.008
Abstract: Sustainable forest management (SFM) requires the balancing of erse values and conflicting management objectives. Climate change adds a further degree of uncertainty to this complex issue. In this study we analysed a Strategic Forest Management Plan (SFMP) from the southwest Yukon, Canada. The SFMP was developed to enable the salvage harvesting of beetle-killed white spruce stands and encourage fuel-abatement treatments to reduce fire risk to local communities. It did not, however, provide a long-term strategy to achieve SFM in the region. In this study, the SFMP served as the basis to develop and evaluate alternative forest management strategies in the context of climate change. Working group discussions with local stakeholders enabled the structuring of a ratings table that helped practitioners and experts to characterize five alternative strategies stemming from the SFMP, based on its main goals and objectives. An Analytic Hierarchy Process (AHP) was then used to balance competing values and objectives and test the alternatives against each other. The strategy 'Manage for multiple values and use' had the highest AHP-score when compared to the four other alternatives (timber, wildlife, fire risk reduction and carbon), which were narrower in scope. It may represent the best balance for the ecological and socio-economic values listed in the SFMP. Although the multiple values (MV) alternative is closest to the current SFMP in terms of scope, this study highlights that there are viable alternatives such as 'manage for wildlife' that achieved similar scores to the MV approach. The current SFMP has great potential to serve as a basis and starting point for a continuous and adaptive planning process for forest management. Exploring the different/alternative strategic directions will help to better address uncertain futures, thereby leading to more sustainable approaches.
Publisher: Springer Science and Business Media LLC
Date: 16-03-2023
Publisher: MDPI AG
Date: 13-03-2018
Publisher: Springer Science and Business Media LLC
Date: 21-05-2020
Publisher: Wiley
Date: 17-04-2020
DOI: 10.1111/EVA.12958
Publisher: Springer Science and Business Media LLC
Date: 06-05-2017
Publisher: Wiley
Date: 07-10-2017
DOI: 10.1002/JOC.4902
Publisher: Wiley
Date: 02-02-2021
DOI: 10.1111/ECOG.05253
Abstract: Extreme weather can have significant impacts on plant species demography however, most studies have focused on responses to a single or small number of extreme events. Long‐term patterns in climate extremes, and how they have shaped contemporary distributions, have rarely been considered or tested. BIOCLIM variables that are commonly used in correlative species distribution modelling studies cannot be used to quantify climate extremes, as they are generated using long‐term averages and therefore do not describe year‐to‐year, temporal variability. We evaluated the response of 37 plant species to base climate (long‐term means, equivalent to BIOCLIM variables), variability (standard deviations) and extremes of varying return intervals (defined using quantiles) based on historical observations. These variables were generated using fine‐grain (approx. 250 m), time‐series temperature and precipitation data for the hottest, coldest and driest months over 39 years. Extremes provided significant additive improvements in model performance compared to base climate alone and were more consistent than variability across all species. Models that included extremes frequently showed notably different mapped predictions relative to those using base climate alone, despite often small differences in statistical performance as measured as a summary across sites. These differences in spatial patterns were most pronounced at the predicted range margins, and reflect the influence of coastal proximity, continentality, topography and orographic barriers on climate extremes. Species occupying hotter and drier locations that are exposed to severe maximum temperature extremes were associated with better predictive performance when modelled using extremes. Understanding how plant species have historically responded to climate extremes may provide valuable insights into our understanding of contemporary distributions and help to make more accurate predictions under a changing climate.
Publisher: MDPI AG
Date: 29-12-2018
Abstract: Ecosystem services (ES) are increasingly recognized as a means to facilitate adaption to environmental change. However, the provisions of ES are likely to be impacted by changes in climate and/or changes in land use. In developing countries, where people are typically dependent on these services for their livelihoods, these impacts are of concern however, very little is known about the changes in provisioning of ES over time. In this study, we assess the perceived changes on ES in the Panchase Mountain Ecological Region of western Nepal. The study area accommodates three distinct ecoregions, ranging from lowland to upland ecosystems and communities. Focus group discussions and key informant interviews were used to collect information on how ES may have changed in the landscape over time. This approach was supported by transect walks, field observations, and secondary sources of information, such as climatic and remote sensing data. Perceived changes on ES in the study region include reduced availability of water, reduced food production, degradation of forest ecosystems, and changes in species compositions. These changes are thought to have impacted other ES, and, in turn, local livelihoods. Management actions that can help local communities foster ES are recommended.
Publisher: Wiley
Date: 12-12-2007
Publisher: CABI Publishing
Date: 21-03-2006
Abstract: The interactions between climate change, fire and forest bio ersity can be characterized as a cascading relationship. Changes in climate directly affect fire frequency and severity. As a result of climate change, a significant increase in fire occurrence and behaviour is predicted to occur over the next 70 years. Climate change will also directly impact the composition of current ecosystems by shifting the fundamental niche of species to higher elevations and/or latitudes, with the changes being most apparent in temperate and boreal latitudes and on mountains in the tropics and subtropics. The alteration and shift of forest ecosystems will be facilitated by an increase in the frequency and severity of forest fires, as these ecosystem disturbances will create the opportunity for the development of new ecosystems. Warmer, drier conditions, coupled with a change in fire behaviour will reduce the resilience of existing ecosystems. The reduced ability to resist and/or recover from disturbance will result in the reduction or complete loss of ecosystem structures required by the fauna and flora that constitute the bio ersity we currently know today. Areas of climatic refuge that exist within landscapes may maintain the ecosystem structures required for some species in the face of direct climate change impacts. Areas that act as both fire and climatic refugia will provide habitat for bio ersity associated with late-successional forests. Species that require late-successional habitat in ecosystems that are intolerant of fire or drought are at greatest risk to climate change and its interaction with fire. The current composition of bio ersity within forested landscapes will change over time and space as species and habitat are both lost and gained in direct or indirect response to climate change.
Publisher: Elsevier BV
Date: 07-2008
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/WF15010
Abstract: In temperate Australia, wildfires are predicted to be more frequent and severe under climate change. This could lead to marked changes in tree mortality and regeneration in the region’s predominant eucalypt forests, which have been burned repeatedly by extensive wildfires in the period 2003–14. Recent studies have applied alternative stable state models to select ‘fire sensitive’ forest types, but comparable models have not been rigorously examined in relation to the more extensive ‘fire tolerant’ forests in the region. We review the effects of increasing wildfire frequency on tree mortality and regeneration in temperate forests of Victoria, south-eastern Australia, based on the functional traits of the dominant eucalypts: those that are typically killed by wildfire to regenerate from seed (‘obligate seeders’) and those that mostly survive to resprout (‘resprouters’). In Victoria, over 4.3 million ha of eucalypt forest has been burned by wildfire in the last decade (2003–14), roughly equivalent to the cumulative area burned in the previous 50 years (1952–2002 4.4 million ha). This increased wildfire activity has occurred regardless of several advancements in fire management, and has resulted in over 350 000 ha of eucalypt forest being burned twice or more by wildfire at short (≤11 year) intervals. Historical and recent evidence indicates that recurrent wildfires threaten the persistence of the ‘fire sensitive’ obligate seeder eucalypt forests, which can facilitate a shift to non-forest states if successive fires occur within the trees’ primary juvenile period (1–20 years). Our review also highlights potential for structural and state changes in the ‘fire tolerant’ resprouter forests, particularly if recurrent severe wildfires kill seedlings and increase tree mortality. We present conceptual models of state changes in temperate eucalypt forests with increasing wildfire frequency, and highlight knowledge gaps relating to the development and persistence of alternative states driven by changes in fire regimes.
Publisher: Wiley
Date: 25-10-2017
DOI: 10.1111/JVS.12575
Publisher: Canadian Institute of Forestry
Date: 10-2012
DOI: 10.5558/TFC2012-098
Abstract: We applied dendrochronology to quantify the effects of climatic variation on white spruce radial growth in southwest Yukon, Canada. Local climate is cold and dry, thus tree growth was primarily limited by moisture, rather than temperature, although the mechanisms varied through time. Regionally, both temperature and precipitation increased in recent decades, in part due to the shift from the negative to positive phase of the Pacific Decadal Oscillation. Climate projections for this region include further increases in temperature and precipitation. Such changes may benefit white spruce growth and disturbance agents like the spruce bark beetle however, specific impacts will depend on the seasonality and magnitude of climatic changes.
Publisher: Wiley
Date: 30-11-2012
Publisher: American Astronomical Society
Date: 20-02-2020
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.SCITOTENV.2017.03.058
Abstract: Vegetation is one of the main resources involve in ecosystem functioning and providing ecosystem services in urban areas. Little is known on the landscape structure patterns of vegetation existing in urban areas at the global scale and the drivers of these patterns. We studied the landscape structure of one hundred cities around the globe, and their relation to demography (population), socioeconomic factors (GDP, Gini Index), climate factors (temperature and rain) and topographic characteristics (altitude, variation in altitude). The data revealed that the best descriptors of landscape structure were amount, fragmentation and spatial distribution of vegetation. Populated cities tend to have less, more fragmented, less connected vegetation with a centre of the city with low vegetation cover. Results also provided insights on the influence of socioeconomics at a global scale, as landscape structure was more fragmented in areas that are economically unequal and coming from emergent economies. This study shows the effects of the social system and climate on urban landscape patterns that gives useful insights for the distribution in the provision of ecosystem services in urban areas and therefore the maintenance of human well-being. This information can support local and global policy and planning which is committing our cities to provide accessible and inclusive green space for all urban inhabitants.
Publisher: MDPI AG
Date: 22-12-2022
DOI: 10.3390/RS15010060
Abstract: Predictive vegetation mapping is an essential tool for managing and conserving high conservation-value forests. Cool temperate rainforests (Rainforest) and cool temperate mixed forests (Mixed Forest, i.e., rainforest spp. overtopped by large remnant Eucalyptus trees) are threatened forest types in the Central Highlands of Victoria. Logging of these forest types is prohibited however, the surrounding native Eucalyptus forests can be logged in some areas of the landscape. This requires accurate mapping and delineation of these vegetation types. In this study, we combine niche modelling, multispectral imagery, and LiDAR data to improve predictive vegetation mapping of these two threatened ecosystems in southeast Australia. We used a dataset of 1586 plots partitioned into four distinct forest types that occur in close proximity in the Central Highlands: Eucalyptus, Tree fern, Mixed Forest, and Rainforest. We calibrated our model on a training dataset and validated it on a spatially distinct testing dataset. To avoid overfitting, we used Bayesian regularized multinomial regression to relate predictors to our four forest types. We found that multispectral predictors were able to distinguish Rainforest from Eucalyptus forests due to differences in their spectral signatures. LiDAR-derived predictors were effective at discriminating Mixed Forest from Rainforest based on forest structure, particularly LiDAR predictors based on existing domain knowledge of the system. For ex le, the best predictor of Mixed Forest was the presence of Rainforest-type understorey overtopped by large Eucalyptus crowns, which is effectively aligned with the regulatory definition of Mixed Forest. Environmental predictors improved model performance marginally, but helped discriminate riparian forests from Rainforest. However, the best model for classifying forest types was the model that included all three classes of predictors (i.e., spectral, structural, and environmental). Using multiple data sources with differing strengths improved classification accuracy and successfully predicted the identity of 88% of the plots. Our study demonstrated that multi-source methods are important for capturing different properties of the data that discriminate ecosystems. In addition, the multi-source approach facilitated adding custom metrics based on domain knowledge which in turn improved the mapping of high conservation-value forest.
Publisher: Wiley
Date: 11-02-2020
DOI: 10.1111/GEB.13038
Abstract: Forest carbon storage is the result of a multitude of interactions among biotic and abiotic factors. Our aim was to use an integrative approach to elucidate mechanistic relationships of carbon storage with biotic and abiotic factors in the natural forests of temperate Australia, a region that has been overlooked in global analyses of carbon‐bio ersity relations. South‐eastern Australia. 2010–2015. Forest trees in 732 plots. We used the most comprehensive forest inventory database available for south‐eastern Australia and structural equation models to assess carbon‐storage relationships with biotic factors (species or functional ersity, community‐weighted mean (CWM) trait values, structural ersity) and abiotic factors (climate, soil, fire history). To assess the consistency of relationships at different environmental scales, our analyses involved three levels of data aggregation: six forest types, two forest groups (representing different growth environments), and all forests combined. Structural ersity was consistently the strongest independent predictor of carbon storage at all levels of data aggregation, whereas relationships with species‐ and functional‐ ersity indices were comparatively weak. CWMs of maximum height and wood density were also significant independent predictors of carbon storage in most cases. In comparison, climate, soil, and fire history had only minor and mainly indirect effects via biotic factors on carbon storage. Our results indicate that carbon storage in our temperate forests was underpinned by tree structural ersity (representing efficient utilisation of space) and by CWM trait values (representing selection effects) more so than by tree species richness or functional ersity. Abiotic effects were comparatively weak and mostly indirect via biotic factors irrespective of the environmental range. Our study highlights the importance of managing forests for functionally important species and to maintain and enhance their structural complexity in order to support carbon storage.
Publisher: Oxford University Press (OUP)
Date: 03-10-2023
DOI: 10.1093/PASJ/PSAD064
Publisher: MDPI AG
Date: 23-02-2023
Abstract: Structural features of the overstorey in managed and unmanaged forests can significantly influence plant community composition. Native Acacia species are common in temperate eucalypt forests in southeastern Australia. In these forests, intense disturbances, such as logging and wildfire, lead to high densities of regenerating trees, shrubs, and herbs. The tree layer is dominated by Acacia and Eucalyptus, that compete intensely for resources in the first decades after stand establishment. The relative abundance and size of Acacia and Eucalyptus varies widely due to stochastic factors such as dispersal, microsite variability, and weather and climatic conditions. This variability may influence the structure and composition of the herbaceous and shrub species. In the temperate forests of southeastern Australia, understorey plant ersity is assumed to be influenced by Acacia species density, rather than Eucalyptus density. To quantify the influence of Acacia and Eucalyptus density on plant community composition, we used remote sensing and machine learning methods to map canopy composition and then compare it to understorey composition. We combined unoccupied aerial vehicle (UAV or drone) imagery, supervised image classifications, and ground survey data of plant composition from post-logging regrowth forests in the Central Highlands of southeastern Australia. We found that aggregation and patch metrics of Eucalyptus and Acacia were strongly associated with understorey plant beta ersity. Increasing aggregation of Acacia and the number of Acacia patches had a significant negative effect on plant beta ersity, while the number of Eucalyptus patches had a positive influence. Our research demonstrates how accessible UAV remote sensing can be used to quantify variability in plant bio ersity in regrowth forests. This can help forest managers map patterns of plant ersity at the stand-scale and beyond to guide management activities across forested landscapes.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/WF15013
Abstract: Soil seedbanks play a key role in the post-fire recruitment of many plant species. Seedbank ersity can be influenced by spatial variability (e.g. geographic location), environmental variability (e.g. soils) and temporal disturbance heterogeneity (e.g. time since fire, TSF) across the landscape. Unlike for aboveground vegetation, relationships between these factors and soil seedbank ersity remain largely unknown. Partitioning the influence of spatial and environmental variability from that of TSF, and explaining how these factors interact with seedbank ersity, will assist conservation managers in their application of prescribed burning. We germinated soil seedbank s les from sites ranging from 1 to 75 years since fire in a heathy-woodland ecosystem across the Otway Ranges in Victoria, Australia. We also measured spatial and environmental variability across sites to partition the influence of these variables and TSF on propagules available for recruitment. We found weak positive relationships between seedbank richness and TSF however, these relationships varied across the landscape. We found composition did not change considerably over time, suggesting, in this ecosystem, pre-fire age is not strongly influencing propagules available for recruitment post-fire. Our results suggest that spatial and environmental variability influence seedbank composition more than TSF.
Publisher: Wiley
Date: 22-09-2023
DOI: 10.1111/ECOG.06435
Publisher: Wiley
Date: 10-2020
DOI: 10.1002/ECS2.3262
Publisher: Wiley
Date: 17-03-2022
DOI: 10.1111/DDI.13515
Abstract: The increasing availability of regional and global climate data presents an opportunity to build better ecological models however, it is not always clear which climate dataset is most appropriate. The aim of this study was to better understand the impacts that alternative climate datasets have on the modelled distribution of plant species, and to develop systematic approaches to enhancing their use in species distribution models (SDMs). Victoria, southeast Australia and the Himalayan Kingdom of Bhutan. We compared the statistical performance of SDMs for 38 plant species in Victoria and 12 plant species in Bhutan with multiple algorithms using globally and regionally calibrated climate datasets. In idual models were compared against one another and as SDM ensembles to explore the potential for alternative predictions to improve statistical performance. We develop two new spatially continuous metrics that support the interpretation of ensemble predictions by characterizing the per‐pixel congruence and variability of contributing models. There was no clear consensus on which climate dataset performed best across all species in either study region. On average, multi‐model ensembles (across the same species with different climate data) increased AUC/TSS/Kappa/OA by up to 0.02/0.03/0.03/0.02 in Victoria and 0.06/0.11/0.11/0.05 in Bhutan. Ensembles performed better than most single models in both Victoria (AUC = 85% TSS = 68%) and Bhutan (AUC = 86% TSS = 69%). SDM ensembles using models fitted with alternative algorithms and/or climate datasets each provided a significant improvement over single model runs. Our results demonstrate that SDM ensembles, built using alternative models of the same climate variables, can quantify model congruence and identify regions of the highest uncertainty while mitigating the risk of erroneous predictions. Algorithm selection is known to be a large source of error for SDMs, and our results demonstrate that climate dataset selection can be a comparably significant source of uncertainty.
Publisher: Springer Science and Business Media LLC
Date: 13-01-2020
Publisher: Elsevier BV
Date: 12-2014
Publisher: Elsevier BV
Date: 2016
Publisher: Springer Science and Business Media LLC
Date: 31-05-2012
Publisher: Oxford University Press (OUP)
Date: 14-11-2019
Abstract: This paper reports observations of a 22 GHz water maser ‘superburst’ in the G25.65+1.05 massive star-forming region, conducted in response to an alert from the Maser Monitoring Organisation (M2O). Very long baseline interferometry (VLBI) observations using the European VLBI Network (EVN) recorded a maser flux density of 1.2 × 104 Jy. The superburst was investipgated in the spectral, structural, and temporal domains and its cause was determined to be an increase in maser path length generated by the superposition of multiple maser emitting regions aligning in the line of sight to the observer. This conclusion was based on the location of the bursting maser in the context of the star-forming region, its complex structure, and its rapid onset and decay.
Publisher: American Astronomical Society
Date: 24-01-2022
Abstract: In this paper, we report new detections of SiO v = 1 and v = 2 J = 1 → 0 masers in the “water fountain” source IRAS 16552−3050, which was observed with the Nobeyama 45 m telescope during 2021 March–April. Water fountains are evolved stars whose H 2 O maser spectra trace high-velocity outflows of km s −1 . This is the second known case of SiO masers in a water fountain, after their prototypical source, W 43A. These SiO masers should shed light on the evolutionary status of this category of evolved stars, which are likely to be at the end of the asymptotic giant branch phase, when the star exhibits the most copious stellar mass loss, followed by development of the complicated morphologies of planetary nebulae. The origin of a large (up to 25 km s −1 ) velocity offset of the SiO masers with respect to the systemic velocity derived from the spectrum of CO J = 2 → 1 line is discussed here.
Publisher: Informa UK Limited
Date: 14-01-2016
Publisher: Elsevier BV
Date: 2008
Publisher: Elsevier BV
Date: 06-2021
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.JENVMAN.2018.10.021
Abstract: Epicormic and basal resprouting promote tree survival and persistence in fire-prone regions worldwide. However, little is known about limits to resprouting effectiveness when severe wildfires increase in frequency. In the extensive fire-tolerant mixed-eucalypt forests of temperate Australia, we examined the effects of one and two high-severity wildfires within six years on relationships between tree size (stem diameter) and resprouting (epicormic and/or basal), and on seedling regeneration. The diameter of eucalypts likely to be topkilled (no epicormic recovery) by high-severity fire increased from ∼15 cm after the first wildfire to ∼22 cm after the second. Middle-sized stems (22-36 cm diameter) were likely to resprout both epicormically and basally after one wildfire, but short-interval wildfires eroded this dual capacity, thereby reducing the probability of survival. Seedling abundance also decreased after two successive fires. Our study indicates that short-interval wildfires increased tree 'escape size', and eroded resprouting success particularly of middle-sized trees, which were too large for basal resprouting but too small for epicormic recovery. This, in combination with reduced seedling recruitment, portends structural and demographic challenges for even the most fire-tolerant forests under emerging fire regimes.
Location: Japan
Start Date: 02-2015
End Date: 06-2018
Amount: $415,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 05-2022
End Date: 05-2025
Amount: $642,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2013
End Date: 12-2016
Amount: $204,676.00
Funder: Australian Research Council
View Funded Activity