Ben P Miller - Academia.edu (original) (raw)

Papers by Ben P Miller

Groeneveld J Esther a Enright N Miller B Lamont B Perry G and Jeltsch F Investigating the Impact of Plant Traits on Community Structure in Fire Prone Woody Vegetation Using a Model of 288 Plant Functional Types in 11th International Mediterranean Ecosystems Conference 2 5 September Perth Western ..., 2007

EGUGA, Apr 1, 2016

Little research has been conducted on the effects of prescription burning on Banksia woodlands, a... more Little research has been conducted on the effects of prescription burning on Banksia woodlands, and, in particular, information on the impacts on soil properties and soil water repellency (SWR) is scarce. Here, we have studied the impact of fire on SWR in a banksia woodland and monitored its evolution in the medium-term. It is expected that results are useful for management and restoration of fire-affected Banksia woodlands. An experimental fire was conducted on May 7th 2015 in Kings Park, Perth, Western Australia (Figure 2). The fire affected an area of 6 ha of mixed Banksia/Allocasuarina woodland under moderate fire intensity (Figure 3). At the time of ignition, the wind speed below the canopy was 1.2 km/h. During the prescribed burning, air temperatures were on average 20 1 C and relative humidity ranged between 45 and 55% (measured using a Kestrel portable weather station). Fuel moisture averaged 11.8% measured using Wiltronics moisture meter) and soil moisture at 1 cm deep ranged from 0.1% to 8.6% (measured with a PR2 soil profile probe attached to a HH2 data logger). Temperatures greater than 120 o C were measured 1 cm below the soil surface using iButton temperature sensors. SWR was measured under lab conditions in oven-dry samples (48 h, 105 o C) with the water drop penetration time (WDPT) test. Figure 2. Detail of the prescribed burning in Kings Park (Perth, WA).

Physiologia Plantarum, Mar 11, 2014

Southwest Australian Banksia woodlands are highly diverse plant communities that are threatened b... more Southwest Australian Banksia woodlands are highly diverse plant communities that are threatened by drought-or temperature-induced mortality due to the region's changing climate. We examined water relations in dominant Banksia menziesii R. Br. trees using magnetic leaf patch clamp pressure (ZIM-) probes that allow continuous, real-time monitoring of leaf water status. Multiple ZIM-probes across the crown were complemented by traditional ecophysiological measurements. During summer, early stomatal downregulation of transpiration prevented midday balancing pressures from exceeding 2.5 MPa. Diurnal patterns of ZIM-probe and pressure chamber readings agreed reasonably well, however, ZIM-probes recorded short-term dynamics, which are impossible to capture using a pressure chamber. Simultaneous recordings of three ZIM-probes evenly spaced along leaf laminas revealed intrafoliar turgor gradients, which, however, did not develop in a strictly basi-or acropetal fashion and varied with cardinal direction. Drought stress manifested as increasing daily signal amplitude (low leaf water status) and occasionally as rising baseline at night (delayed rehydration). These symptoms occurred more often locally than across the entire crown. Microclimate effects on leaf water status were strongest in crown regions experiencing peak morning radiation (East and North). Extreme spring temperatures preceded the sudden death of B. menziesii trees, suggesting a temperature-or humidity-related tipping point causing rapid hydraulic failure as evidenced by collapsing ZIM-probe readings from an affected tree. In a warmer and drier future, increased frequency of B. menziesii mortality will result in significantly altered community structure and ecosystem function.

Background/question/methods: Banksia woodlands in south-west Australia are currently facing multi... more Background/question/methods: Banksia woodlands in south-west Australia are currently facing multiple threats, including fragmentation and drought- or temperature-induced mortality due to the region’s changing climate. We examined, in unprecedented detail, water relations in Banksia menziesii R. Br. trees using a novel magnetic leaf patch clamp pressure probe (ZIM-probe) that allows continuous, real-time monitoring of leaf water status. Several ZIM-probes were installed across the crown and complemented by sap flow and traditional ecophysiological spot measurements. Results/conclusions: Drought stress manifested as increasing daily signal amplitudes. Drought stress symptoms occurred more often locally than across the entire crown. Diurnal recordings during summer showed that stomatal down-regulation of transpiration commenced in the morning when vapour pressure deficit (VPD) reached 2-2.5 kPa. This early reduction in stomatal conductance prevented midday balancing pressures from exceeding 2.5 MPa. During peak summer, water status in the east and north responded more strongly to VPD than in south and west. Sap flow response to VPD reached a saturation plateau at ca. 2.5 kPa coincident with the onset of stomatal down-regulation. Unexpectedly high spring temperatures preceded the sudden death of several B. menziesii trees, suggesting a temperature- or VPD-related tipping point causing rapid hydraulic failure as evidenced by collapsing ZIM-probe readings recorded on an affected tree. The ZIM-probe’s high sensitivity renders it an ideal tool for drought stress monitoring and evaluating adaptive forest and woodland management strategies. In a warmer and drier future, local mortality events in B. menziesii populations may occur more frequently with strong impacts on community structure and ecosystem functioning.

Restoration Ecology, Aug 12, 2021

Mining activity causes major changes in site topography, soil physical and chemical properties, h... more Mining activity causes major changes in site topography, soil physical and chemical properties, hydrology, and biological assemblages. Reassembling plant communities in these highly altered environments is dependent on interactions between environmental drivers and management intervention techniques through time, yet the long‐term effects of these interactions have rarely been quantified. This study examined a 19‐year‐old, postmining woodland restoration chronosequence in southwest Australia to understand plant community compositional development in postmine restoration sites. We tested the effects of environmental drivers (rainfall regimes, site aspect, slope) and management intervention techniques (substrate ripping and material properties) in terms of four restoration criteria: species richness, plant density, vegetation cover, and compositional similarity to reference sites. Irrespective of environmental drivers or management intervention techniques, vegetation cover increased through time, while plant density and species richness declined. Bray–Curtis similarity to reference communities remained unchanged. Within these trends, ripping and first‐year rainfall significantly affected restoration criteria outcomes; species richness and plant density were greatest when rainfall in the first winter immediately following site restoration was low but followed by a high summer rainfall. The most effective ripping depth was dependent on rainfall, deep‐ripped sites performed best when rainfall was high, and nonripped sites performed best under low‐mean rainfall conditions. Measured restoration criteria had not reached the levels of the target reference community after 19 years, which may be attributable to the still‐developing vegetation structure. This emphasizes the importance of assessing postmining restoration outcomes over longer time frames (>>5 years) with implications for determining appropriate, time‐dependent completion criteria.

Communications Earth & Environment

Wildfires are increasing in size and severity and fire seasons are lengthening, largely driven by... more Wildfires are increasing in size and severity and fire seasons are lengthening, largely driven by climate and land-use change. Many plant species from fire-prone ecosystems are adapted to specific fire regimes corresponding to historical conditions and shifts beyond these bounds may have severe impacts on vegetation recovery and long-term species persistence. Here, we conduct a meta-analysis of field-based studies across different vegetation types and climate regions to investigate how post-fire plant recruitment, reproduction and survival are affected by fires that occur outside of the historical fire season. We find that fires outside of the historical fire season may lead to decreased post-fire recruitment, particularly in obligate seeding species. Conversely, we find a general increase in post-fire survival in resprouting species. Our results highlight the trade-offs that exist when considering the effects of changes in the seasonal timing of fire, an already present aspect of c...

Ecological Applications

Connecting scientific research and government policy is essential for achieving objectives in sus... more Connecting scientific research and government policy is essential for achieving objectives in sustaining biodiversity in an economic context. Our approach to connecting theoretical ecology, applied ecology, and policy was devised using principles of restoration ecology and the requisite methodology to restore biodiverse ecosystems. Using a threatened ecological community (TEC) with >120 plant species, we posit our approach as a guide for interpreting and achieving regulatory compliance (i.e., government conditions) enacted to manage or offset environmental impacts of development. We inform the scientific approach necessary to delivering outcomes appropriate to policy intent and biodiverse restoration through theoretical and applied research into the ecological restoration of the highly endemic flora of banded ironstone formations of the Mid West of Western Australia. Our approach (1) defines scale‐appropriate restoration targets that meet regulatory compliance (e.g., Government o...

EGU General Assembly Conference Abstracts, Apr 1, 2015

Australian Journal of Botany, 2021

The rapid expansion of urban areas worldwide is leading to native habitat loss and ecosystem frag... more The rapid expansion of urban areas worldwide is leading to native habitat loss and ecosystem fragmentation and degradation. Although the study of urbanisation’s impact on biodiversity is gaining increasing interest globally, there is still a disconnect between research recommendations and urbanisation strategies. Expansion of the Perth metropolitan area on the Swan Coastal Plain in south-western Australia, one of the world’s thirty-six biodiversity hotspots, continues to affect the Banksia Woodlands (BWs) ecosystem, a federally listed Threatened Ecological Community (TEC). Here, we utilise the framework of a 1989 review of the state of knowledge of BWs ecology and conservation to examine scientific advances made in understanding the composition, processes and functions of BWs and BWs’ species over the last 30 years. We highlight key advances in our understanding of the ecological function and role of mechanisms in BWs that are critical to the management of this ecosystem. The most e...

The New phytologist, Jan 14, 2015

Inventors in the field of mechanical and electronic engineering can access multitudes of componen... more Inventors in the field of mechanical and electronic engineering can access multitudes of components and, thanks to standardization, parts from different manufacturers can be used in combination with each other. The introduction of BioBrick standards for the assembly of characterized DNA sequences was a landmark in microbial engineering, shaping the field of synthetic biology. Here, we describe a standard for Type IIS restriction endonuclease-mediated assembly, defining a common syntax of 12 fusion sites to enable the facile assembly of eukaryotic transcriptional units. This standard has been developed and agreed by representatives and leaders of the international plant science and synthetic biology communities, including inventors, developers and adopters of Type IIS cloning methods. Our vision is of an extensive catalogue of standardized, characterized DNA parts that will accelerate plant bioengineering.

The Plant Cell, 2015

Establishment of arbuscular mycorrhizal interactions involves plant recognition of diffusible sig... more Establishment of arbuscular mycorrhizal interactions involves plant recognition of diffusible signals from the fungus, including lipochitooligosaccharides (LCOs) and chitooligosaccharides (COs). Nitrogen-fixing rhizobial bacteria that associate with leguminous plants also signal to their hosts via LCOs, the so-called Nod factors. Here, we have assessed the induction of symbiotic signaling by the arbuscular mycorrhizal (Myc) fungal-produced LCOs and COs in legumes and rice (Oryza sativa). We show that Myc-LCOs and tetra-acetyl chitotetraose (CO4) activate the common symbiosis signaling pathway, with resultant calcium oscillations in root epidermal cells of Medicago truncatula and Lotus japonicus. The nature of the calcium oscillations is similar for LCOs produced by rhizobial bacteria and by mycorrhizal fungi; however, Myc-LCOs activate distinct gene expression. Calcium oscillations were activated in rice atrichoblasts by CO4, but not the Myc-LCOs, whereas a mix of CO4 and Myc-LCOs a...

Background: Following mineral-sand mining in the northern sandplains near Eneabba, southwestern A... more Background: Following mineral-sand mining in the northern sandplains near Eneabba, southwestern Australia, rehabilitation managers have the difficult task of restoring shrubland communities of exceptional plant species richness. Management aims to restore a fully functional and self-sustaining shrubland community with similar vegetation and resilience properties to that of the surrounding natural vegetation. This project examined the performance of the restoration program by Iluka Resources Ltd. (and their predecessors) by comparing current vegetation properties and their response to fires on previously mined land versus the surrounding natural shrubland. As biomass accumulates post-restoration, fires will return as a natural disturbance factor and, as a result, a desirable measure of restoration success might include the ability of the postmined lands to recover from disturbance. Original objectives: To evaluate the ecology of rehabilitated minesites by comparing their plant species composition, spatial arrangement, functional attributes and response to experimental fire with that of the surrounding heathlands. While work was done on spatial arrangement of plants this is ongoing and is not reported here. Findings, results, outcomes: Pre-burnt plant species diversity, composition, structure and key functional attributes in four mined sites rehabilitated 8 (R8) to 24 (R24) years ago were compared with those of surrounding natural areas classified on the basis of substrate type (low and high sand dunes, shallow sand swales, sand over laterite and sand over limestone). The rehabilitated sites (except R8) had more species (about 140) than natural sites (about 100) with 12-37% species in common with natural sites. Floristic composition was most similar to the local swales and dunes (physically closest). Two strong colonizers, the fire-susceptible Acacia blakelyi and the fire-tolerant Melaleuca leuropoma, were universally present. Plant densities were about a quarter to half those of natural sites. Fire-resprouters were under-represented. Growth-form distributions were most similar to those of the dunes, with some woody shrubs up to 2.5 m tall present. Greater iron levels and soil hardness (penetrability) were the only soil factors consistently greater in rehabilitated sites. Following experimental fires at the same study sites, species richness fell by 22-41% in rehabilitated sites but increased by 4-29% in natural sites. Species present before fire were reduced by 40-56% in rehabilitated sites and 4-12% in natural sites. Only 42-66% of resprouting species recovered in rehabilitated sites, whereas 96-100% recovered in natural sites. Nonsprouting species recruitment was also lower in rehabilitated (18-57%) than natural (67-85%) sites. Seedling mortality over the first summer after fire was higher in rehabilitated sites (59-86% death of individuals) than in natural sites (14-60%). Principle coordinates analyses (PCoA) ordination showed that fire altered the floristic composition of rehabilitated sites much more than it did in natural sites, mostly attributable to the loss of the extant resprouter species. Western Australian Herbarium. 1998+. FloraBase-The Western Australian Flora. Department of Environment and Conservation. URL http://florabase.calm.wa.gov.au/.

Ecology, 2007

The fire-prone shrublands of southwestern Australia are renowned for their high plant species div... more The fire-prone shrublands of southwestern Australia are renowned for their high plant species diversity and prominence of canopy seed storage (serotiny). We compared species richness, abundance, and life history attributes for soil and canopy seed banks in relation to extant vegetation among four sites with different substrate conditions and high species turnover (50-80%) to identify whether this unusual community-level organization of seed storage might contribute to maintenance of high species richness. Soil seed bank (SSB) densities were low to moderate (233-1435 seeds/m 2) compared with densities for other Mediterranean-type vegetation and were lowest for sites with highest canopy seed bank (CSB) species richness and lowest nutrient availability, but not richness or abundance of resprouters. Annuals were infrequent in the lowest nutrient sites, but there was no evidence that small SSB size was due to low seed inputs or a trade-off between seed production/storage and seed size in response to low nutrient availability. Sorensen's similarity between SSB and extant vegetation was 26-43% but increased to 54-57% when the CSB was included, representing levels higher than reported for most other ecosystems. Resprouting species were well represented in both the SSB and CSB, and there was no evidence for lower seed production in resprouters than in non-sprouters overall. The SSB and CSB held no species in common and were characterized by markedly different seed dispersal attributes, with winged or small seeds in the CSB and seeds dispersed by ants, birds, and wind (though none with wings) in the SSB. There was no evidence of spatial differentiation in the distribution of seeds of SSB species between vegetated and open microsites that might facilitate species coexistence, but most woody non-sprouters showed aggregation at scales of 1-2 m, implying limited seed dispersal. High similarity between overall seed bank (SSB þ CSB) and extant species composition, high number of resprouting species, and seed dispersal processes before (SSB) and after fire (CSB) leading to differential spatial aggregation of postfire recruits from the two seed bank types may buffer species composition against rapid change and provide a mechanism for maintaining species coexistence at the local scale.

Diversity and Distributions, 2003

The efficiency of four nonparametric species richness estimators-first-order Jackknife, second-or... more The efficiency of four nonparametric species richness estimators-first-order Jackknife, second-order Jackknife, Chao2 and Bootstrapwas tested using simulated quadrat sampling of two field data sets (a sandy 'Dune' and adjacent 'Swale') in high diversity shrublands (kwongan) in southwestern Australia. The data sets each comprised > 100 perennial plant species and > 10 000 individuals, and the explicit (x-y coordinate) location of every individual. We applied two simulated sampling strategies to these data sets based on sampling quadrats of unit sizes 1/400th and 1/100th of total plot area. For each site and sampling strategy we obtained 250 independent sample curves, of 250 quadrats each, and compared the estimators' performances by using three indices of bias and precision: MRE (mean relative error), MSRE (mean squared relative error) and OVER (percentage overestimation). The analysis presented here is unique in providing sample estimates derived from a complete, field-based population census for a high diversity plant community. In general the true reference value was approached faster for a comparable area sampled for the smaller quadrat size and for the swale field data set, which was characterized by smaller plant size and higher plant density. Nevertheless, at least 15-30% of the total area needed to be sampled before reasonable estimates of S t (total species richness) were obtained. In most field surveys, typically less than 1% of the total study domain is likely to be sampled, and at this sampling intensity underestimation is a problem. Results showed that the second-order Jackknife approached the actual value of S t more quickly than the other estimators. All four estimators were better than S obs (observed number of species). However, the behaviour of the tested estimators was not as good as expected, and even with large sample size (number of quadrats sampled) all of them failed to provide reliable estimates. First-and secondorder Jackknives were positively biased whereas Chao2 and Bootstrap were negatively biased. The observed limitations in the estimators' performance suggests that there is still scope for new tools to be developed by statisticians to assist in the estimation of species richness from sample data, especially in communities with high species richness.

Plant and Soil, May 6, 2019

Aims Understanding limitations to plant recruitment is a key element in devising effective restor... more Aims Understanding limitations to plant recruitment is a key element in devising effective restoration of semiarid ecosystems: only when these limitations are identified can management interventions be effectively targeted. This study investigated demographic, seed and microsite limitations to establishing native plant species in a semi-arid, post-mining restoration context. Methods We assessed ex situ and in situ germination and in situ emergence for eight key tree, shrub and annual herb species. We sowed non-treated seeds and seeds that were pre-treated to overcome dormancy, at differing densities and across diverse microsites to assess the roles of dormancy, seed density and microsite type as limiting factors for seedling recruitment. Results We found that dormancy loss, in situ germination and in situ emergence limited one or more species, and we were able to improve emergence of one species by seed addition and targeted manipulation of microsites. Conclusions The study has resulted in management implications including the importance of understanding methods to overcome dormancy to maximise germination; identifying key and species-specific demographic transitions; the importance of species-specific testing of seed sowing density; and the potential for increasing emergence by sowing seeds in furrows rather than broadcasting across rises and furrows, or on flat, unripped soil.

Journal of Vegetation Science, 2008

The drivers of spatial patterning among plant species and the implications of those patterns for ... more The drivers of spatial patterning among plant species and the implications of those patterns for the structure and function of plant communities are of ongoing interest and debate. Here we explore the spatial patterning shown by individual species in species-rich plant communities. We (1) compare the levels of aggregation in these communities to those observed in other species-rich communities, in particular tropical rain forests, and (2) consider how abiotic conditions might influence the levels of aggregation observed. Location: We describe the spatial structure of four species-rich Mediterranean-type shrubland communities near Eneabba, Western Australia. The four sites each contain > 10 000 plants and up to 113 species, and differ in substrate-type, species richness and composition. Methods: We analysed the spatial patterning of all species with more than 20 individuals (233 species patterns), and used point process models for aggregated patterns to separate first-order gradient effects from second-order clustering. Results: Aggregated distributions were most common at all sites, but especially at the site with the highest resource availability and heterogeneity and lowest species richness. A Poisson cluster process best described the majority of aggregated species, suggesting that local interactions drive fine-scale patterns in these communities. Conclusions: As with many previous studies, we found that most species showed strong local aggregation. The proportion of species showing aggregation was less than has been described in species-rich tropical rainforests but was higher than observed in many temperate plant communities. The highest proportion of aggregated species was seen at the most resource-abundant site; this is in direct contrast to conceptual models that suggest that competition should be weakest, and aggregation most prevalent, in the most resource-limited sites.

Austral Ecology, 2018

Native bushland fragmented by urbanization often experiences increased cover of flammable weeds, ... more Native bushland fragmented by urbanization often experiences increased cover of flammable weeds, reduced biomass turnover and an absence of fuel management combined with increased ignitions. Depending on species' mobility and dispersal traits, and the extent of burns within urban remnants, such fires may reduce individual survival rates or limit natural recolonization. We monitored the survival of mygalomorph spiders for a year following high-intensity and low-intensity fires in Banksia woodland remnants in urban Perth. Of the 257 burrows found, 115 spiders were confirmed to initially survive after intense wildfire, but none were confirmed alive after 12 months. In sharp contrast, only one spider from 103 observed burrows was confirmed dead after a low-intensity prescribed fire. As there were instances of our monitored mygalomorphs relocating a short distance following only low intensity fires, we also tested whether predation rates were higher in burnt than unburnt areas. Higher rates of predation were found in burnt areas, but this was strongly influenced by both site and predator type. We recommend further consideration of low-intensity prescribed fire as well as alternative fuel management approaches in urban remnants to better conserve mygalomorph spider populations and other taxa with limited dispersal and/or mobility capabilities.