Papers by Greg L Steenbeeke
Telopea, 2013
A new species of Thismia from New South Wales. A new species, Thismia megalongensis, is described... more A new species of Thismia from New South Wales. A new species, Thismia megalongensis, is described, illustrated and compared with other Australian species. A key to Australian species of Thismia is included. Habitat details, the conservation status, and phylogenetic affinities of the new species are discussed.
Journal of Biogeography, 2017
Aim Achlorophyllous mycoheterotrophic plants and mycorrhizal fungi often have highly specific int... more Aim Achlorophyllous mycoheterotrophic plants and mycorrhizal fungi often have highly specific interactions that potentially limit the plants' distribution and diversification potential. However, specificity in biotic interactions may differ considerably over a species' distribution range and therefore interactions need to be studied over their entire range to assess their evolution in space and time. The present study investigates the biogeographical history of the interaction between five closely related mycoheterotrophic Thismia species and arbuscular mycorrhizal fungi over the distribution range of the plant species. Location Temperate southeast Australia and New Zealand. Methods Phylogenetic relationships of Thismia (nrITS and mtcob) and their arbuscular mycorrhizal fungi (partial nrSSU) were reconstructed based on data from 65 plant specimens. The diversification times in Thismia were estimated with a Bayesian relaxed clock approach using a Dioscoreales framework (nrSSU, mtatp1, mtmatR, mtnad1 b-c). Ancestral geographical ranges were reconstructed using a maximum likelihood approach. The same approach was used to reconstruct ancestral mycorrhizal associations. Results Our analysis shows that Thismia plants have highly specific, phylogenetically conserved and evolutionarily persistent interactions with Rhizophagus fungi. Nevertheless, Thismia was able to diversify and radiate recently due to the wide geographical distribution of the host fungi. In addition, we find that although the mycorrhizal interactions of this clade of mycoheterotrophs are strictly bound to a fungal lineage, host switches remain possible. Main conclusions In this clade of closely related mycoheterotrophs, dependency on highly specific fungal interactions is the result of phylogenetic niche conservatism, acting over at least 12 million years. Nevertheless, plants that are dependent on highly specific fungal interactions have ample opportunities to disperse and radiate over the geographical range of their hosts. Our study highlights the need to link the ecology and evolution of species interactions over broad geographical and evolutionary scales for understanding mycorrhizal interactions.
Orchids with scarce occurrence records: The case of the endangered Botany Bay Bearded Greenhood
Ecological Management & Restoration
Climate
In rapidly urbanizing areas, natural vegetation becomes fragmented, making conservation planning ... more In rapidly urbanizing areas, natural vegetation becomes fragmented, making conservation planning challenging, particularly as climate change accelerates fire risk. We studied urban forest fragments in two threatened eucalypt-dominated (scribbly gum woodland, SGW, and ironbark forest, IF) communities across ~2000 ha near Sydney, Australia, to evaluate effects of fire frequency (0–4 in last 25 years) and time since fire (0.5 to >25 years) on canopy structure, habitat quality and biodiversity (e.g., species richness). Airborne lidar was used to assess canopy height and density, and ground-based surveys of 148 (400 m2) plots measured leaf area index (LAI), plant species composition and habitat metrics such as litter cover and hollow-bearing trees. LAI, canopy density, litter, and microbiotic soil crust increased with time since fire in both communities, while tree and mistletoe cover increased in IF. Unexpectedly, plant species richness increased with fire frequency, owing to increas...
Climate, 2022
In rapidly urbanizing areas, natural vegetation becomes fragmented, making conservation planning ... more In rapidly urbanizing areas, natural vegetation becomes fragmented, making conservation planning challenging, particularly as climate change accelerates fire risk. We studied urban forest fragments in two threatened eucalypt-dominated (scribbly gum woodland, SGW, and ironbark forest, IF) communities across ~2000 ha near Sydney, Australia, to evaluate effects of fire frequency (0–4 in last 25 years) and time since fire (0.5 to >25 years) on canopy structure, habitat quality and biodiversity (e.g., species richness). Airborne lidar was used to assess canopy height and density, and ground-based surveys of 148 (400 m2) plots measured leaf area index (LAI), plant species composition and habitat metrics such as litter cover and hollow-bearing trees. LAI, canopy density, litter, and microbiotic soil crust increased with time since fire in both communities, while tree and mistletoe cover increased in IF. Unexpectedly, plant species richness increased with fire frequency, owing to increased shrub richness which offset decreased tree richness in both communities. These findings indicate biodiversity and canopy structure are generally resilient to a range of times since fire and fire frequencies across this study area. Nevertheless, reduced arboreal habitat quality and subtle shifts in community composition of resprouters and obligate seeders signal early concern for a scenario of increasing fire frequency under climate change. Ongoing assessment of fire responses is needed to ensure that biodiversity, canopy structure and ecosystem function are maintained in the remaining fragments of urban forests under future climate change which will likely drive hotter and more frequent fires.
Australasian Journal of Environmental Management
Biodiversity values under the New South Wales (NSW) Biodiversity Conservation Act 2016 are assess... more Biodiversity values under the New South Wales (NSW) Biodiversity Conservation Act 2016 are assessed in part according to the number and cover of native plant species within each of six growth form groups (trees, shrubs, grasses and grass-like, forbs, ferns, and others). Here we revise 19 growth form descriptions and use an independent expert process to allocate the most common (primary) growth form to the native terrestrial vascular plant flora of NSW. Independent allocations made by three botanists concurred for 6,153 taxa (84.7 per cent of the flora) and the remaining 1,112 taxa were resolved via a structured consensus making process. Allocation of each taxon to primary growth form has generated a single point of reference for the most common growth form for each native vascular plant species, expressed in its mature state across the extent of its range in NSW. The work presented here was undertaken to support transparent, repeatable and rigorous assessments of the richness and cover of growth form groups for the NSW Biodiversity Assessment Method. However, our approach and findings will be relevant to any government agency, industry group or researcher that uses plant growth forms to simplify ecological complexity or to assess the site-scale biodiversity values of terrestrial vegetation.
Journal of Biogeography, 2017
Aim Achlorophyllous mycoheterotrophic plants and mycorrhizal fungi often have highly specific int... more Aim Achlorophyllous mycoheterotrophic plants and mycorrhizal fungi often have highly specific interactions that potentially limit the plants' distribution and diversification potential. However, specificity in biotic interactions may differ considerably over a species' distribution range and therefore interactions need to be studied over their entire range to assess their evolution in space and time. The present study investigates the biogeographical history of the interaction between five closely related mycoheterotrophic Thismia species and arbuscular mycorrhizal fungi over the distribution range of the plant species. Location Temperate southeast Australia and New Zealand. Methods Phylogenetic relationships of Thismia (nrITS and mtcob) and their arbuscular mycorrhizal fungi (partial nrSSU) were reconstructed based on data from 65 plant specimens. The diversification times in Thismia were estimated with a Bayesian relaxed clock approach using a Dioscoreales framework (nrSSU, mtatp1, mtmatR, mtnad1 b-c). Ancestral geographical ranges were reconstructed using a maximum likelihood approach. The same approach was used to reconstruct ancestral mycorrhizal associations. Results Our analysis shows that Thismia plants have highly specific, phylogenetically conserved and evolutionarily persistent interactions with Rhizophagus fungi. Nevertheless, Thismia was able to diversify and radiate recently due to the wide geographical distribution of the host fungi. In addition, we find that although the mycorrhizal interactions of this clade of mycoheterotrophs are strictly bound to a fungal lineage, host switches remain possible. Main conclusions In this clade of closely related mycoheterotrophs, dependency on highly specific fungal interactions is the result of phylogenetic niche conservatism, acting over at least 12 million years. Nevertheless, plants that are dependent on highly specific fungal interactions have ample opportunities to disperse and radiate over the geographical range of their hosts. Our study highlights the need to link the ecology and evolution of species interactions over broad geographical and evolutionary scales for understanding mycorrhizal interactions.
Telopea
The new species Thismia megalongensis (Thismiaceae) from New South Wales, Australia, is described... more The new species Thismia megalongensis (Thismiaceae) from New South Wales, Australia, is described, illustrated and compared with other Australian species. A key to Australian species of Thismia is included. Habitat details, conservation status, and phylogenetic affinities of the new species are discussed.
Earlier work has shown that the genus Alloxylon is distinctly separate from other members of subt... more Earlier work has shown that the genus Alloxylon is distinctly separate from other members of subtribe Embothriinae of Proteaceae. Phenetic analysis of herbarium specimens of the four species in Alloxylon were conducted on 31 characters, although only 12 were found to be useful in encompassing all the variation within the genus for those specimens examined. Four distinct clusters, each of which correspond to a described species, are found in the analysis groupings when plotted in two dimensions and assessed in three dimensions by visual interpretation of the spatial model of principal coordinates. The greatest reliability of separation of accepted species occurred when characters most similar to those used in a key to the species are used in the analysis. The species Alloxylon brachycarpum and A. flammeum are very similar, being reliably separated by only a single character, and with the third tropical species (A. wickhamii) forms a cluster encompassing the three tropical species standing separate from the single subtropical species (A. pinnatum). Comparison of duplicate sheets within a single species (A. wickhamii) held at two different herbaria also provided a test of the ability of the analysis to cluster like materials satisfactorily and allowed a comparison of the extent of variation within a species and within an individual.
Rehabilitation and restoration of linkages between isolated basalt outcrop remnants in the north-eastern NSW Brigalow Belt South Bioregion
Thismia megalongensis (Thismiaceae), a new species of Thismia from New South Wales. A new species... more Thismia megalongensis (Thismiaceae), a new species of Thismia from New South Wales. A new species, Thismia megalongensis, is described, illustrated and compared with other Australian species. A key to Australian species of Thismia is included. Habitat details, conservation status, and phylogenetic affinities of the new species are discussed.
Australasian Journal of Environmental Management, 2019
Biodiversity values under the New South Wales (NSW) Biodiversity Conservation Act 2016 are assess... more Biodiversity values under the New South Wales (NSW) Biodiversity Conservation Act 2016 are assessed in part according to the number and cover of native plant species within each of six growth form groups (trees, shrubs, grasses and grass-like, forbs, ferns, and others). Here we revise 19 growth form descriptions and use an independent expert process to allocate the most common (primary) growth form to the native terrestrial vascular plant flora of NSW. Independent allocations made by three botanists concurred for 6,153 taxa (84.7 per cent of the flora) and the remaining 1,112 taxa were resolved via a structured consensus making process. Allocation of each taxon to primary growth form has generated a single point of reference for the most common growth form for each native vascular plant species, expressed in its mature state across the extent of its range in NSW. The work presented here was undertaken to support transparent, repeatable and rigorous assessments of the richness and cover of growth form groups for the NSW Biodiversity Assessment Method. However, our approach and findings will be relevant to any government agency, industry group or researcher that uses plant growth forms to simplify ecological complexity or to assess the site-scale biodiversity values of terrestrial vegetation.
Aim Achlorophyllous mycoheterotrophic plants and mycorrhizal fungi often have highly specific int... more Aim Achlorophyllous mycoheterotrophic plants and mycorrhizal fungi often have highly specific interactions that potentially limit the plants' distribution and diversification potential. However, specificity in biotic interactions may differ considerably over a species' distribution range and therefore interactions need to be studied over their entire range to assess their evolution in space and time. The present study investigates the biogeographical history of the interaction between five closely related mycoheterotrophic Thismia species and arbus-cular mycorrhizal fungi over the distribution range of the plant species. Location Temperate southeast Australia and New Zealand. Methods Phylogenetic relationships of Thismia (nrITS and mtcob) and their arbuscular mycorrhizal fungi (partial nrSSU) were reconstructed based on data from 65 plant specimens. The diversification times in Thismia were estimated with a Bayesian relaxed clock approach using a Dioscoreales framework (nrSSU, mtatp1, mtmatR, mtnad1 b-c). Ancestral geographical ranges were reconstructed using a maximum likelihood approach. The same approach was used to reconstruct ancestral mycorrhizal associations. Results Our analysis shows that Thismia plants have highly specific, phyloge-netically conserved and evolutionarily persistent interactions with Rhizophagus fungi. Nevertheless, Thismia was able to diversify and radiate recently due to the wide geographical distribution of the host fungi. In addition, we find that although the mycorrhizal interactions of this clade of mycoheterotrophs are strictly bound to a fungal lineage, host switches remain possible. Main conclusions In this clade of closely related mycoheterotrophs, dependency on highly specific fungal interactions is the result of phylogenetic niche conservatism, acting over at least 12 million years. Nevertheless, plants that are dependent on highly specific fungal interactions have ample opportunities to disperse and radiate over the geographical range of their hosts. Our study highlights the need to link the ecology and evolution of species interactions over broad geographical and evolutionary scales for understanding mycorrhizal interactions.
South African Journal of Science, 2001
Serpentine rocks occupy less than 1% of the area of New South Wales, Australia, existing as isola... more Serpentine rocks occupy less than 1% of the area of New South Wales, Australia, existing as isolated outcrops. The degree of endemism of the serpentine vegetation is high. The serpentinite outcrop at Baryulgil in the humid climate of north-eastern NSW is one of a string of such outcrops along the eastern seaboard of Australia, but is spatially isolated. A comparative study of the vegetation of the serpentinite at Baryulgil with that of the adjacent sandstone and granite, on sites with both northerly and southerly aspects, shows that the vegetation structure and composition on the serpentinite differs significantly from that on the other substrates. The species composition of the Baryulgil serpentine vegetation is distinct. Its height, basal area, and overstorey cover are low, and there is no variation in the structure and biomass of the vegetation with aspect. The overstorey of the serpentine vegetation is dominated either by Eucalyptus acmenoides and E. ophitica or by Allocasuarina torulosa. Eucalyptus ophitica is the only species endemic to the Baryulgil serpentinite outcrop. The supression of vegetation development on the serpentinite in comparison with other substrates does not appear to be attributable to either nutrient deficiency (as evidenced by phosphorus levels) or to levels of potentially phytotoxic elements.
The new species Thismia megalongensis (Thismiaceae) from New South Wales, Australia, is described... more The new species Thismia megalongensis (Thismiaceae) from New South Wales, Australia, is described, illustrated and
compared with other Australian species. A key to Australian species of Thismia is included. Habitat details, conservation
status, and phylogenetic affinities of the new species are discussed. (Telopea 16, 165-174)
To answer a ques7on of how I became interested in growing orchids is to iden7fy the 7me when I ch... more To answer a ques7on of how I became interested in growing orchids is to iden7fy the 7me when I changed from being a passive observer to being one who sought out plants which I was interested in growing. I had always been around orchids -the penalty of being a second genera7on grower I guess. My father had a diverse collec7on of cymbidiums, mainly older styles because that was what he had collected over the preceding decade or more. He had connec7ons though -to the Deane family of the Blue Mountains and the folk at Cecil Park and Wondabah -and was trying to improve the types he grew. He also had the usual 'hangers on' that a Sydney region grower had -the odd plant of Dendrobium nobile and Paphiopedilum insigne, and the ubiquitous reed stem epidendrums. These crucifix orchids were under the trees in the front garden. Mainly they were red flowered types, with a few plants of orange and even possibly a pinky-purple one. That one and the oranges were clumping plants, but the reds were sprawling around under the trees and made a lovely carpet, although the shading meant they weren't in flower very oAen.
At a recent meeƟng of the ANOS Sydney Group I was asked by Mike Harrison was asked about the heri... more At a recent meeƟng of the ANOS Sydney Group I was asked by Mike Harrison was asked about the heritage of the name Brachypeza archytas. This species is one of the real oddiƟes of ANOS, as it is one of the few orchids that occurs in an Australian territory that is not within the typical geographic delineaƟon of the ANOS region. It comes from the small Indian Ocean territory of Christmas Island.
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Papers by Greg L Steenbeeke
compared with other Australian species. A key to Australian species of Thismia is included. Habitat details, conservation
status, and phylogenetic affinities of the new species are discussed. (Telopea 16, 165-174)