ORCID Profile
0000-0002-0408-0082
Current Organisation
University of Adelaide
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Research Topics
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.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Environmental Science and Management | Ecological Applications not elsewhere classified | Plant Biology | Natural Resource Management | Terrestrial Ecology | Conservation And Biodiversity | Ecology | Ecological Applications | Environmental Technologies | Land And Parks Management | Environmental Impact Assessment | Population Ecology | Ecosystem Function | Invertebrate Biology | Plant Physiology | Plant Pathology | Environmental Rehabilitation (excl. Bioremediation) | Life Histories (Incl. Population Ecology) |
ANZSRC Socio-Economic Objective (SEO)
Living resources (flora and fauna) | Remnant vegetation and protected conservation areas | Integrated (ecosystem) assessment and management | Ecosystem Assessment and Management of Forest and Woodlands Environments | Living resources (flora and fauna) | Control of pests and exotic species | Control of pests and exotic species | Environmental and resource evaluation not elsewhere classified | Remnant vegetation and protected conservation areas | Flora, Fauna and Biodiversity of environments not elsewhere classified | Environmentally Sustainable Mineral Resource Activities not elsewhere classified | Ecosystem Assessment and Management of Sparseland, Permanent Grassland and Arid Zone Environments | Living resources (flora and fauna) | Mining Flora, Fauna and Biodiversity | Global climate change adaptation measures | Forest and Woodlands Flora, Fauna and Biodiversity
Related Links
Publications
Do wide crowns in arid woodland trees reflect hydraulic limitation and reduction of self-shading?
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/FP14022
Abstract: In arid regions many tree species develop broad crowns. A number of hypotheses involve trade-offs between growth in height and horizontal spreading, but there is no explanation for the switch from vertical to horizontal growth during development. Using Acacia papyrocarpa Benth as a model, we measured tree height and crown shape across different sites and topographic positions. We also measured δ13C of phyllodes from crown tops and lateral spreading branches. Trees were significantly taller at the base of a hill, where water availability is typically greater, than on the adjacent steep hillslope. In contrast, δ13C from the treetops was not significantly different across this topographic gradient, despite variation in tree height. In addition, δ13C was higher at treetops than in lower, lateral branches. These observations are consistent with hydraulic limitation to tree height. The shape of mature and young crowns in open environments was not symmetrical. At all sites, branches were shortest, but tree crowns tallest, on south-facing (i.e. shadiest) aspect of crowns. This suggests that light limitation may also affect crown development. If upper branches become water-limited and lower branches light-limited, then middle lateral branches become the less-stressed part of the crown and may grow more, producing a broad crown.
Diversity Changes During Pioneer Stages in a Subhumid Pampean Grassland Succession
Publisher: JSTOR
Date: 1987
DOI: 10.2307/2425703
Interactive effects of arbuscular mycorrhizal symbiosis, intraspecific competition and resource availability on Trifolium subterraneum cv. Mt. Barker
Publisher: Wiley
Date: 03-1999
Opening the black box: outcomes of interactions between arbuscular mycorrhizal (AM ) and non‐host genotypes of M edicago depend on fungal identity, interplay between P<
Publisher: Wiley
Date: 12-12-2013
DOI: 10.1111/PCE.12237
Abstract: We investigated the physiology that underlies the influence of arbuscular mycorrhizal (AM) colonization on outcomes of interactions between plants. We grew Medicago truncatula A17 and its AM-defective mutant dmi1 in intragenotypic (two plants per pot of the same genotype, x2) or intergenotypic (one plant of each genotype, 1 + 1) combinations, inoculated or not with Rhizophagus irregularis (formerly Glomus intraradices) or Gigaspora margarita. We measured plant growth, colonization, contributions of AM and direct P uptake pathways using (32)P, and expression of plant Pi transporter genes at two levels of P supply. A17 (x2) responded positively to inoculation only at low P. The response was enhanced with 1 + 1 even at high P where colonization in A17 was reduced. With R. irregularis P uptake by the AM pathway was unaffected by P supply, whereas with G. margarita, the AM pathway was lower at high P, and direct uptake higher. Gene expression varied and was unrelated to P uptake through the two pathways. There was no evidence of plant control of P uptake via R. irregularis at high P but there was via G. margarita. Importantly, growth responses of plant genotypes grown alone did not predict outcomes of intergenotypic interactions.
Plant Litter: Light Interception and Effects on an Old-Field Plant Community
Publisher: Wiley
Date: 06-1991
DOI: 10.2307/1940602
Does nitrogen affect the interaction between a native hemiparasite and its native or introduced leguminous hosts?
Publisher: Wiley
Date: 22-09-2016
DOI: 10.1111/NPH.14181
Abstract: Associations between plants and nitrogen (N)‐fixing rhizobia intensify with decreasing N supply and come at a carbon cost to the host. However, what additional impact parasitic plants have on their leguminous hosts’ carbon budget in terms of effects on host physiology and growth is unknown. Under glasshouse conditions, Ulex europaeus and Acacia paradoxa either uninfected or infected with the hemiparasite Cassytha pubescens were supplied (high nitrogen (HN)) or not (low nitrogen ( LN )) with extra N. The photosynthetic performance and growth of the association were measured. Cassytha pubescens significantly reduced the maximum electron transport rates and total biomass of U. europaeus but not those of A. paradoxa , regardless of N. Infection significantly decreased the root biomass of A. paradoxa only at LN , while the significant negative effect of infection on roots of U. europaeus was less severe at LN . Infection had a significant negative impact on host nodule biomass. Ulex europaeus supported significantly greater parasite biomass (also per unit host biomass) than A. paradoxa , regardless of N. We concluded that rhizobia do not influence the effect of a native parasite on overall growth of leguminous hosts. Our results suggest that C. pubescens will have a strong impact on U. europaeus but not A. paradoxa , regardless of N in the field.
Community Structure in Grazed and Ungrazed Grassland Sites in the Flooding Pampa, Argentina
Publisher: JSTOR
Date: 1989
DOI: 10.2307/2425663
Plant litter: Its dynamics and effects on plant community structure
Publisher: Springer Science and Business Media LLC
Date: 1991
DOI: 10.1007/BF02858763
Competition and resource availability in an annual plant community dominated by an invasive species, Carrichtera annua (L. Aschers.), in South Australia
Publisher: Springer Science and Business Media LLC
Date: 2003
Socio-Cultural Values of Ecosystem Services from Oak Forests in the Eastern Himalaya
Publisher: MDPI AG
Date: 15-04-2019
DOI: 10.3390/SU11082250
Abstract: Identification and assessment of socio-cultural values of ecosystem services are increasingly important for the planning and management of forest resources. Key information necessary is how different forest user groups perceive and prioritize different ecosystem services based on their local setting. We assessed the socio-cultural values of ecosystem services of high-altitude oak forests in Western Bhutan using participatory approaches with two important forest users: local communities and forest experts. We found that these forests serve as a pool of 22 ecosystem services under four MEA categories of provisioning (9), regulating (8), supporting (2), and cultural (3) services. Fresh water was unanimously identified as the most valuable service, as well as the most vulnerable, by both the groups. The priorities of local communities inclined towards provisioning and cultural services due to their dependence on these services for their livelihood and wellbeing. Forest experts’ priorities were more evenly spread over three categories of services: provisioning, regulating, and supporting services, reflecting their broader interest in resource management, bio ersity conservation, and climate change mitigation. Several regulating and supporting services were not easily identified by many villagers, suggesting that bridging the priorities of local interests with broader national forestry goals may require public partnerships and integrated decision-making about the entire suite of ecosystem services. Several management interventions proposed by the groups were presented for consideration by local users, scientists, and policy makers. For all ongoing and future ecosystem service assessments, we recommend the integration of socio-cultural values with biophysical and monetary assessments to fully value the benefits from the high-altitude oak forests.
The potential for deep groundwater use by Acacia papyrocarpa (Western myall) in a water‐limited environment
Publisher: Wiley
Date: 14-11-2016
DOI: 10.1002/ECO.1791
Patch dynamics in arid lands: localized effects of Acacia papyrocarpa on soils and vegetation of open woodlands of south Australia
Publisher: Wiley
Date: 08-2000
Indirect Effects of Litter on Woody Seedlings Subject to Herb Competition
Publisher: JSTOR
Date: 11-1991
DOI: 10.2307/3545257
Impacts of a native parasitic plant on an introduced and a native host species: implications for the control of an invasive weed
Publisher: Oxford University Press (OUP)
Date: 10-11-2008
DOI: 10.1093/AOB/MCN214
Native faunal communities depend on habitat from non-native plants in novel but not in natural ecosystems
Publisher: Springer Science and Business Media LLC
Date: 03-2016
Plant-mycorrhizal fungi feedbacks: potential accomplices of Avena barbata’s high invasiveness
Publisher: Springer Science and Business Media LLC
Date: 14-07-2018
Markovian chains and the role of history in succession
Publisher: Elsevier BV
Date: 1990
Pioneer Stages in a Secondary Succession of a Pampean Subhumid Grassland
Publisher: Elsevier BV
Date: 1986
Forces that structure plant communities: quantifying the importance of the mycorrhizal symbiosis
Publisher: Wiley
Date: 08-11-2010
Effects of sheep exclusion on the soil seed bank and annual vegetation in chenopod shrublands of South Australia
Publisher: Elsevier BV
Date: 06-1999
Biological soil crust and vascular plant interactions in Western Myall (Acacia papyrocarpa) open woodland in South Australia
Publisher: Wiley
Date: 07-2019
DOI: 10.1111/JVS.12764
Effects of slashing on native and invasive species, and community structure of a remnant natural grassland of South Australia
Publisher: Wiley
Date: 10-2022
DOI: 10.1111/AVSC.12704
Abstract: We investigated the feasibility of slashing as a management tool to reduce the abundance of the exotic invasive species Avena barbata and favour native species and ersity in remnants of semi‐arid native grasslands. We asked how slashing affects: (1) the seed production and seed bank of A. barbata , (2) the mortality of perennial native tussock grasses, and (3) plant community composition. Near Burra, Mid North region of South Australia. We established two parallel experiments in an invaded grassland: one in a stand dominated by exotic and invasive species (“poor” condition), and the other in a less‐degraded stand with an abundance of native perennial grasses (“good” condition). The experiments had a randomized block design (six blocks) with three treatments each: no slashing, slashing once a year or slashing every other year, applied over 3 years. We assessed the effects of the treatments on the number of seeds per m 2 and soil seed bank of A. barbata , number of death native tussock grasses, and floristic composition and ersity. Slashing reduced seed production and the soil seed bank of A. barbata in both stands . Slashing increased the mortality of native grasses in the stand in good condition, and slightly changed floristic composition only in the stand in poor condition. Here, slashing decreased the abundance of the invasive species A. barbata and Bromus rigens but favoured other exotic species. No changes in species richness or ersity were detected. The slight response of the plant community to slashing suggests that these grasslands are resistant to changes in management. However, the reduction in seed production and soil seed bank of A. barbata suggest that longer term application of slashing could reduce its abundance and allow native species to recruit. The mortality of native tussocks can, however, negate the benefit of reducing abundance of invasive species.
Resource pre‐emption, rather than extending the growing season of native grass assemblages, reduces invasion by exotic species
Publisher: Wiley
Date: 10-2021
DOI: 10.1111/AVSC.12613
Abstract: In Mediterranean‐type systems, invasive C3 annual grasses appear early in the season and can pre‐empt resources and attain a competitive dominance over native perennial grasses. Here, we investigated whether planting C3 and C4 native grasses (a) combined, so that resources are extracted over a longer period, or (b) at higher density would make planted communities more competitive against invasive species. Para Woodlands Reserve, near Adelaide, South Australia. In 72 experimental plots, native grasses were planted in combinations of seasonal patterns (three levels single‐season assemblages with either C3 or C4 and extended season with both C3 and C4) and planting density (two levels high = 44 plants/m 2 and low = 20 plants/m 2 ). Data were collected on native plant survival and biomass, invasive biomass and soil properties. Overall, C3 native grasses were superior competitors against both invasive C3 grasses and native C4 grasses. We found no interaction between the combination of C3 and C4 grasses planted together and density of planting. Assemblages with higher densities were successful at reducing exotic plant biomass however, there was a trade‐off with reduced in idual performance among the native plants. Even though in idual plants were larger in the low‐density treatment, total biomass was lower in these plots suggesting that density limits the growth of native communities as a whole. The C3 native plants were planted earlier than the C4 native plants because of differences in phenology and therefore likely pre‐empted resources and gained a size advantage, making them the superior competitor. Native perennial grasses can outcompete exotic plants for resources if planted earlier in the season. This resource pre‐emption appears to be more important than resource use over a longer period with C3 and C4 plants together and could be an effective restoration strategy.
Effects of ash and four types of litter on the establishment ofEucalyptus obliqua
Publisher: Informa UK Limited
Date: 1996
Effects of leaf litter on woody seedlings in xeric successional communities
Publisher: Springer Science and Business Media LLC
Date: 2000
Dormancy-breaking and germination requirements for seeds of Acacia papyrocarpa, Acacia oswaldii and Senna artemisioides ssp.×coriacea, three Australian arid-zone Fabaceae species
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/BT14077
Abstract: Physical dormancy is common in seeds of arid-land legumes. Improved understanding of germination requirements of hard-seeded species will further our understanding of arid lands and aid restoration projects. We studied the germination responses of Acacia papyrocarpa (Benth.), A. oswaldii (F.Muell) and Senna artemisioides (Gaudich. ex DC.) Randell ssp. × coriacea (Benth.) Randell from a chenopod shrubland in South Australia. Imbibition testing indicated that all three species had physical dormancy, but the proportion of dormant seeds was lower in A. oswaldii. This corresponded to a thinner testa in this species. Mechanisms tested to scarify seeds included mechanical scarification and different durations of wet or dry heat. Mechanically scarified seeds germinated readily, reaching maximum numbers in 10–15 days, independently of incubation temperatures, with the exception of S. artemisioides seeds, which germinated at a slower rate in cooler temperatures. Overall, wet heat was more effective than dry heat to alleviate physical dormancy, whereas dry heat in some cases resulted in seed mortality. On the basis of these results, it is recommended that seeds of A. papyrocarpa and S. artemisoides be pretreated with wet heat in future restoration programs. No pre-treatment is required for dormancy loss in A. oswaldii seeds. The different responses of seeds of these species suggest that their populations have varying strategies for persistence in this unpredictable environment.
Germination requirements and responses to leaf litter of four species of eucalypt
Publisher: Springer Science and Business Media LLC
Date: 09-1996
DOI: 10.1007/BF00333933
Correlations between environmental factors, the biomass of exotic annual grasses and the frequency of native perennial grasses
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/BT05083
Abstract: The species composition of temperate grasslands in the mid-north of South Australia has been radically altered from a system dominated by native perennial grasses to a system dominated by Mediterranean annual grasses. This study investigated the importance of chemical and physical soil characteristics, topographical features and climatic variables on the abundance of native and exotic grass species in nine ungrazed grasslands. Overall, climatic and other abiotic factors were highly variable. In addition, past management practices and original species composition are generally unknown, leading to further unexplained variation in the data. On a large spatial scale (among sites), the abundance of exotic annual grasses was positively correlated with mean annual rainfall, and on any scale, with finer soil textures and higher soil organic carbon levels. The most abundant annual grass, Avena barbata (Pott ex Link), was generally associated with soil factors denoting higher soil fertility. The abundance of native perennial grass species was not correlated with any environmental variables at any scale. The various native perennial grass species did not show clear associations with soil factors, although they tended to be associated with factors denoting lower soil fertility. However, at small spatial scales (within some sites) and among sites, the abundances of exotic annual and native perennial grasses were strongly negatively correlated. The results suggest that at the present time, rainfall and soil properties are important variables determining the abundance of annual grasses. The driving variables for the abundance of perennial grasses are less clear. They may be controlled by other factors or extreme rainfall events, which were not surveyed. In addition, they are likely to be controlled by competitive interactions with the annual grasses.
Invasive success of exotic wild oat depends on nutrient availability and competition in temperate grasslands of southern Australia
Publisher: Springer Science and Business Media LLC
Date: 28-01-2022
Direct and indirect effects of exotic annual grasses on species composition of a South Australian grassland
Publisher: Wiley
Date: 02-2003
Desert shrubs have negative or neutral effects on annuals at two levels of water availability in arid lands of South Australia
Publisher: Wiley
Date: 15-10-2008
Multispecies interactions among a plant parasite, a pollinator and a seed predator affect the reproductive output of an invasive plant, Cytisus scoparius
Publisher: Wiley
Date: 28-03-2011
Underground friends or enemies: model plants help to unravel direct and indirect effects of arbuscular mycorrhizal fungi on plant competition
Publisher: Wiley
Date: 09-02-2010
DOI: 10.1111/J.1469-8137.2009.03162.X
Abstract: *We studied the effects of two arbuscular mycorrhizal (AM) fungi, singly or together, on the outcome of competition between a host (tomato cultivar, wild-type (WT)) and a surrogate nonhost (rmc, a mycorrhiza-defective mutant of WT) as influenced by the contributions of the direct and AM phosphorus (P) uptake pathways to plant P. *We grew plants singly or in pairs of the same or different genotypes (inoculated or not) in pots containing a small compartment with (32)P-labelled soil accessible to AM fungal hyphae and determined expression of orthophosphate (P(i)) transporter genes involved in both AM and direct P uptake. *Gigaspora margarita increased WT competitive effects on rmc. WT and rmc inoculated with Glomus intraradices both showed growth depressions, which were mitigated when G. margarita was present. Orthophosphate transporter gene expression and (32)P transfer showed that the AM pathway operated in single inoculated WT, but not in rmc. *Effects of AM fungi on plant competition depended on the relative contributions of AM and direct pathways of P uptake. Glomus intraradices reduced the efficiency of direct uptake in both WT and rmc. The two-fungus combination showed that interactions between fungi are important in determining outcomes of plant competition.
A soil-borne generalist pathogen regulates complex plant interactions
Publisher: Springer Science and Business Media LLC
Date: 27-09-2018
Fallen logs as sources of patchiness in chenopod shrublands of South Australia
Publisher: Elsevier BV
Date: 10-2013
Response to grazing after nine years of cattle exlusion in a Flooding Pampa grassland, Argentina
Publisher: Springer Science and Business Media LLC
Date: 12-1988
DOI: 10.1007/BF00045635
Secondary seed dispersal of Erodiophyllum elderi, a patchily distributed short-lived perennial in the arid lands of Australia
Publisher: Wiley
Date: 25-11-2010
Long‐term influence of fallen logs on patch formation and their effects under contrasting grazing regimes
Publisher: Wiley
Date: 22-10-2014
DOI: 10.1111/AEC.12204
Evidence for species‐specific plant responses to soil microbial communities from remnant and degraded land provides promise for restoration
Publisher: Wiley
Date: 02-2018
DOI: 10.1111/AEC.12567
DIFFERENCES IN SEED BIOLOGY OF ANNUAL PLANTS IN ARID LANDS: A KEY INGREDIENT OF THE STORAGE EFFECT
Publisher: Wiley
Date: 11-2005
DOI: 10.1890/05-0304
Endemic macrophyte is more plastic than two cosmopolitan species in fluctuating water levels and nutrient-enriched conditions
Publisher: Informa UK Limited
Date: 21-12-2020
Shade facilitates an invasive stem succulent in a chenopod shrubland in South Australia
Publisher: Wiley
Date: 10-2003
Response of selected South Australian native plant species to Phytophthora cinnamomi
Publisher: Wiley
Date: 17-02-2012
Priority effects produced by plant litter result in non-additive competitive effects
Publisher: Springer Science and Business Media LLC
Date: 25-07-2008
DOI: 10.1007/S00442-008-1110-2
Abstract: Litter may indirectly affect competitive interactions. It is not clear whether these changes are additive or non-additive indirect effects. Non-additivity could result from: (1) changes in biomass allocation patterns by competitors towards organs not directly involved in resource acquisition (e.g., longer hypocotyls) (2) changes in the proportion of different functional groups (e.g., grasses and forbs) that possess different competitive abilities or (3) through priority effects caused by subtle changes in timing of emergence. We used a combination of field and glasshouse experiments in which Eucalyptus obliqua seedlings were grown either with or without leaf litter (grass litter/eucalypt litter), and with or without competitors. Eucalypt species growing in the field and in pots attained more biomass with litter than without when competitors were absent. Competition substantially decreased the biomass of eucalypt seedlings. Competitive intensity was heavily influenced by litter type and was most intense in the presence of grass litter. Litter produced a small change in patterns of biomass allocation in the competing herbaceous vegetation, and there was a slight (marginally non-significant) indication of a change in the proportion of grasses relative to forbs when litter was present. However, when the integral of competitor biomass over time was used to calculate competitive intensity, the combined effects of the experimental factors (litter and competition) became additive, suggesting that the effect of leaf litter on the timing of germination and establishment in the grasses and forbs, relative to that of Eucalyptus seedlings, was the principal mechanism by which leaf litter altered the interaction strength of the species studied.
Multiple effects of shrubs on annual plant communities in arid lands of South Australia
Publisher: No publisher found
Date: 2002
Cyclic dormancy, temperature and water availability control germination of Carrichtera annua, an invasive species in chenopod shrublands
Publisher: Wiley
Date: 10-04-2008
Interactive effects of drought and shade on three arid zone chenopod shrubs with contrasting distributions in relation to tree canopies
Publisher: Wiley
Date: 02-2004
A native parasitic plant affects the performance of an introduced host regardless of environmental variation across field sites
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/FP17358
Abstract: Increasing evidence from glasshouse studies shows that native hemiparasitic plants can significantly impact the performance and growth of introduced host plants. We investigated the effect of the native Australian hemiparasite Cassytha pubescens R.Br. on the introduced shrub Ulex europaeus L. at three field sites in South Australia. Parasite infection significantly decreased midday PSII efficiency (ΦPSII) and the maximum electron transport rates (ETRmax) of U. europaeus across sites. The impact of C. pubescens on the photosynthetic performance of U. europaeus may have been caused by infected plants having significantly lower N and K, but higher Fe and Al than uninfected plants at all sites. Significant Al and Fe enrichment in infected plants may be possibly due to the parasite indirectly inducing rhizosphere acidification. At two sites, C. pubescens significantly affected host Fv/Fm, indicating chronic photoinhibition in response to infection. The impact of infection on Fv/Fm was greatest at the wettest site, in line with an experiment where C. pubescens had more impact under high water availability. At this site, infected plants also had the highest foliar Fe and Al. The C isotope (δ13C) of infected plants was significantly lower than that of uninfected plants at only one site. Unusually, the δ13C of the parasite was the same as or significantly higher than that of the hosts. There were no site effects on parasite Fv/Fm or ΦPSII however, ETRmax and δ13C varied across sites. The results suggest that this native parasite has negative effects on U. europaeus in the field, as was found for glasshouse studies. The abundance of this introduced weed in Australia could be negatively affected by C. pubescens infection.
The piosphere revisited: plant species patterns close to waterpoints in small, fenced paddocks in chenopod shrublands of South Australia
Publisher: Elsevier BV
Date: 08-2002
Ninety years of change on the TGB Osborn Vegetation Reserve, Koonamore: a unique research opportunity
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/RJ18022
Abstract: The TGB Osborn Vegetation Reserve, on Koonamore station in the NE pastoral area of South Australia, is the longest-running vegetation monitoring project of its type in Australia. In 1925, a 4-km2 rectangle in a heavily overgrazed area was fenced to exclude rabbits and sheep, and permanent quadrats and photo-points set up to record changes. The area is predominantly chenopod shrubland, with an open woodland tree layer. After the initial elimination of rabbits, control slackened and rabbit numbers increased until the 1970s, when intense elimination efforts resumed, together with the arrival of myxomatosis and rabbit haemorrhagic disease viruses. Consequently, the reserve has had 50 years without sheep, followed by 40 years virtually without either sheep or rabbits. Changes over that time have been very striking, and they have been recorded regularly via mapped quadrats and photopoints. The objective of this paper is to highlight opportunities for making use of this database for researching several interesting ecological questions.
Microdisturbances in Oldfields and Forests: Implications for Woody Seedling Establishment
Publisher: JSTOR
Date: 05-1990
DOI: 10.2307/3565360
Native hemiparasite and light effects on photoprotection and photodamage in a native host
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/FP15132
Abstract: Plants infected with hemiparasites often have lowered rates of photosynthesis, which could make them more susceptible to photodamage. However, it is also possible that infected plants increase their photoprotective capacity by changing their pigment content and/or engagement of the xanthophyll cycle. There are no published studies investigating infection effects on host pigment dynamics and how this relates to host susceptibility to photodamage whether in high (HL) or low light (LL). A glasshouse experiment was conducted where Leptospermum myrsinoides Schltdl. either uninfected or infected with Cassytha pubescens R.Br. was grown in HL or LL and pigment content of both host and parasite were assessed. Infection with C. pubescens significantly decreased all foliar pigment concentrations (except chlorophyll b) in L. myrsinoides in both HL and LL. Xanthophyll cycle (violaxanthin, antheraxanthin, zeaxanthin VAZ) and chlorophyll (Chl) pigments decreased in parallel in response to infection, hence, VAZ/Chl of the host was unaffected by C. pubescens in either HL or LL. Pre-dawn and midday de-epoxidation state [(A + Z)/(V + A + Z)] of L. myrsinoides was also unaffected by infection in both HL and LL. Thus, L. myrsinoides infected with C. pubescens maintained similar photoprotective capacity per unit chlorophyll and engagement of the xanthophyll cycle as uninfected plants. Even though midday quantum yield (ΦPSII) of HL plants was affected by infection, pre-dawn maximum quantum yields (Fv/Fm) of hosts were the same as uninfected plants whether in HL or LL. This ability of L. myrsinoides to maintain photoprotective capacity/engagement when infected by C. pubescens thereby preventing photodamage could explain this host’s tolerance to hemiparasite infection.
Grazing orchids: impact of florivory on two species of Caladenia (Orchidaceae)
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/BT08140
Abstract: Herbivory is considered a major threat in many of the orchid-species recovery plans in Australia. Kangaroos and rabbits are the most commonly implicated herbivores however, no studies have attempted to confirm their role. Regular monitoring of several populations of Caladenia rigida R.S.Rogers and C. tentaculata Schldl. during 3 years in the Mount Lofty Ranges, South Australia, revealed that up to 94% of flowers and 36% of seed capsules were browsed, whereas leaf herbivory was less prevalent. Furthermore, patterns of herbivory varied markedly among sites and across years. In two seasons, predation of C. rigida flowers inside a kangaroo- and rabbit-proof exclosure was equal to or higher than outside the exclosure. Florivory within populations was influenced by proximity to the habitat edge, although the direction of this response differed among sites. Various types of mesh cages were erected around plants to elucidate the size and type of herbivores. Plants protected from florivores were almost three times more likely to produce seed than were exposed plants however, some cage types reduced pollination. Video surveillance confirmed the role of the white-winged chough, Corcorax melanorh hos, as a florivore. The present study is the first one to identify a herbivore unequivocally, quantify the intensity and extent of floral herbivory across a range of populations, and assess the potential cost of florivory to the direct reproductive output of orchids.
The influence of the hemiparasitic angiosperm Cassytha pubescens on photosynthesis of its host Cytisus scoparius
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/FP09135
Abstract: Infection with Cassytha pubescens R.Br, an Australian native hemiparasitic plant, can lead to death of the invasive shrub, Cytisus scoparius L. Link (Scotch broom). We examined the influence of C. pubescens on photosynthetic physiology of C. scoparius to determine whether this might contribute to death of infected plants. Infected C. scoparius had significantly lower photosynthetic rates, stomatal conductance and transpiration, and higher Ci (internal [CO2]), than uninfected plants. Rapid light response curves, determined using chlorophyll fluorescence, indicated significantly lower light-saturated electron transport rates and lower quantum yields for infected plants relative to uninfected plants. However, Rubisco content did not differ between infected and uninfected plants, suggesting the lower photosynthetic rates were most likely due to stomatal closure, rather than lower photosynthetic capacity. As a consequence of lower assimilation rates, PSII efficiency was lower in infected plants than uninfected plants across the diurnal cycle. Infected plants also had significantly lower pre-dawn Fv/Fm values and slower recovery from exposure to high light than uninfected plants. Our results suggest that infected C. scoparius are more susceptible to photodamage than uninfected plants. Combined with lower carbon fixation rates, this could contribute to the poor performance and even death of infected plants.
High water availability increases the negative impact of a native hemiparasite on its non-native host
Publisher: Oxford University Press (OUP)
Date: 23-12-2015
DOI: 10.1093/JXB/ERV548
Disturbance effects on plant community diversity: spatial scales and dominance hierarchies
Publisher: Springer Science and Business Media LLC
Date: 05-1991
DOI: 10.1007/BF00033208
The relationship between the diversity of arbuscular mycorrhizal fungi and grazing in a meadow steppe
Publisher: Springer Science and Business Media LLC
Date: 24-09-2011
Interactions after death: plant litter controls priority effects in a successional plant community
Publisher: Springer Science and Business Media LLC
Date: 1993
DOI: 10.1007/BF00323500
Seed traits and fate support probable primary dispersal of a native hemi-parasitic vineCassytha pubescens(Lauraceae) byIsoodon obesulus, an endangered marsupial, in southern Australia
Publisher: Informa UK Limited
Date: 09-03-2022
The role of seed limitation and resource availability in the recruitment of native perennial grasses and exotics in a South Australian grassland
Publisher: Wiley
Date: 30-08-2005
Seed viability in declining populations of Caladenia rigida (Orchidaceae): are small populations doomed?
Publisher: Wiley
Date: 07-12-2010
Choose Local: Dung Addition from Native Herbivores Can Produce Substantial Positive Effects on the Growth of Native Grasses Compared to Livestock Dung
Publisher: Springer Science and Business Media LLC
Date: 12-07-2023
DOI: 10.1007/S42729-023-01380-7
Abstract: Livestock grazing and dung deposition can increase soil nutrients, contributing to the dominance of exotic species. Recent research suggests that native herbivore grazing has positive effects on native vegetation and soil health. However, little is known about the effects of native herbivore dung on plant growth and its potential implications for the restoration of degraded grasslands. This study examined the effects of dung addition from a native herbivore, kangaroo ( Macropus giganteus ), and ruminant livestock, sheep ( Ovis aries ), on biomass production and nutrient uptake of the native perennial wallaby grass ( Rytidosperma auriculatum ) and the annual exotic wild oat ( Avena barbata ), two of the most abundant grasses from the temperate grasslands of southern Australia. We conducted a glasshouse experiment, adding each type of dung to each plant species grown without competition in pots containing soil with a nutrient composition similar to that of old fields. Kangaroo dung produced higher wallaby grass aboveground biomass than other treatments and less wild oat aboveground biomass than the control. Kangaroo dung affected nutrient uptake but not nutrient concentration. Sheep dung had no effect. We demonstrated that native herbivores and livestock dung can have different effects on the biomass of native and invasive grasses. The higher nutrient uptake in wallaby grass appeared to be a consequence of the higher biomass production, suggesting that the effects produced by kangaroo dung could be related to its chemical and biological characteristics rather than its nutrient composition. Incorporating native herbivores’ dung or facilitating their presence can improve restoration outcomes in degraded grasslands.
The enigma of male eating disorders: A critical review and synthesis
Publisher: Elsevier BV
Date: 11-2017
Growth and competition of Cytisus scoparius, an invasive shrub, and Australian native shrubs
Publisher: Springer Science and Business Media LLC
Date: 1999
The effect of heat and smoke on the soil seed banks of heathlands on permanent freshwater swamps
Publisher: Wiley
Date: 19-10-2020
DOI: 10.1111/AEC.12957
Does light influence the relationship between a native stem hemiparasite and a native or introduced host?
Publisher: Oxford University Press (OUP)
Date: 02-2016
DOI: 10.1093/AOB/MCV193
The storage effect: definition and tests in two plant communities
Publisher: Cambridge University Press
Date: 16-01-2014
Response of vegetation cover to climate variability in protected and grazed arid rangelands of South Australia
Publisher: Elsevier BV
Date: 02-2019
Multiple Indirect Effects of Plant Litter Affect the Establishment of Woody Seedlings in Old Fields
Publisher: Wiley
Date: 09-1994
DOI: 10.2307/1939632
Differing effects of shade‐induced facilitation on growth and survival during the establishment of a chenopod shrub
Publisher: Wiley
Date: 21-11-2003
Interactions between soil properties, soil microbes and plants in remnant-grassland and old-field areas: a reciprocal transplant approach
Publisher: Springer Science and Business Media LLC
Date: 10-2018
Effects of Casuarina pauper litter and grove soil on emergence and growth of understorey species in arid lands of South Australia
Publisher: Elsevier BV
Date: 11-2001
Effects of competition, resource availability and invertebrates on tree seedling establishment
Publisher: Wiley
Date: 15-06-2005
Experimental evaluation of the foliar flag hypothesis using fruits of Rhus glabra (L.)
Publisher: Springer Science and Business Media LLC
Date: 02-1993
DOI: 10.1007/BF00321193
Changes in seed dispersal processes and the potential for between-patch connectivity for an arid land daisy
Publisher: Wiley
Date: 03-2012
DOI: 10.1890/11-0651.1
Abstract: Dispersal is a major and critical process in population biology that has been particularly challenging to study. Animals can have major roles in seed dispersal even in species that do not appear specifically adapted to animal-aided dispersal. This can occur by two processes: direct movement of diaspores by animals and modification of landscape characteristics by animals in ways that greatly influence dispersal. We exploited the production of large, persistent dispersal structures (seed heads, henceforth) by Erodiophyllum elderi (Asteraceae), a daisy from arid Australia, to further understand secondary dispersal. Seed head dispersal on and off animal tracks in eight E. elderi patches was monitored for 9.5 months by periodically recording the location of marked seed heads. Sites were located inside a reserve that excludes sheep but not kangaroos, and in a nearby area with both kangaroos and sheep. The distance moved and likelihood of seed head movement was higher in areas with sheep, and especially along animal tracks. There was clear evidence that seed heads were channeled down animal tracks during large rainfall events. Seed head dispersal away from patches occurred to a limited extent via their physical contact with sheep and potentially via wind dispersal. Thus, the advantages of this study system allowed us to demonstrate the two postulated effects of herbivores on dispersal via direct movement of seed heads, and two distinct indirect effects through landscape modification by herbivores from the creation of animal tracks and the denudation of vegetation.
Soil phosphorus heterogeneity and mycorrhizal symbiosis regulate plant intra-specific competition and size distribution
Publisher: Springer Science and Business Media LLC
Date: 09-2002
DOI: 10.1007/S00442-002-1022-5
Abstract: We investigated the interactive effects of soil phosphorus (P) heterogeneity, plant density and mycorrhizal symbiosis on plant growth and size variability of Trifolium subterraneum. We set up mesocosms (trays 49×49 cm and 12 cm deep) with the same amount of available P, but distributed either homogeneously or heterogeneously, in randomly arranged cells (7×7 cm each) with high or low available P. The trays were planted with either 1 or 4 seedlings of T. subterraneum per cell. Half of the trays were inoculated with spores of the mycorrhizal fungus Gigaspora margarita. We harvested the plants when leaves just started to overlap, 8 weeks after planting. Plants growing in high P cells had the lowest percentage infection, but the highest mean shoot and root biomass and root length. The mean size of the plants in each cell was determined mainly by local P concentration. However, in plants growing in high density, low P cells, ca. 20% of the variability in plant biomass was explained by the number of adjacent cells with high P. Patchy trays had the highest total shoot biomass, independently of mycorrhizal infection or plant density. Inoculated trays (M) had higher total shoot biomass and relative competition intensity (measured as reduction in plant biomass due to increased density) than non-inoculated trays (NM). Plant density reduced the plant response to mycorrhizal infection, and its effect was independent of P distribution. All populations growing in patchy trays, and low density mycorrhizal ones, had the highest plant-size inequality, presumably because patchy distribution of P and mycorrhizal infection increased competitive asymmetry. We conclude that mycorrhizal symbiosis has the potential to strongly influence plant population structure when soil nutrient distribution is heterogeneous because it promotes pre-emption of limiting resources.
Directionality, convergence, and rate of change during early succession in the Inland Pampa, Argentina
Publisher: Wiley
Date: 04-1990
DOI: 10.2307/3235662
The role of the permanent soil seed bank in early stages of a post-agricultural succession in the Inland Pampa, Argentina
Publisher: Springer Science and Business Media LLC
Date: 03-1988
DOI: 10.1007/BF00045612
Specialized seedling strategies I: seedlings in stressful environments
Publisher: Cambridge University Press
Date: 18-09-2008
Why do some species in arid lands increase under grazing? Mechanisms that favour increased abundance of Maireana pyramidata in overgrazed chenopod shrublands of South Australia
Publisher: Wiley
Date: 21-07-2009
The impact of a novel invasive species,Orbea variegata(African carrion flower), on the chenopod shrublands of South Australia
Publisher: Elsevier BV
Date: 1999
Bees and white spiders: unravelling the pollination syndrome of Caladenia rigida (Orchidaceae)
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/BT08135
Abstract: Orchids of the genus Caladenia have been shown to utilise two quite different pollination strategies, namely species-specific sexual deception of thynnine wasps and a more generalist strategy attracting a larger spectrum of foraging insects. While baiting techniques have enabled the identification of numerous pollinators of sexually deceptive Caladenia, insects that pollinate food-advertising species have received little attention. The present study employed a multidisciplinary approach to better evaluate the pollination syndrome of the white spider orchid, Caladenia rigida R.S.Rogers, a species previously reported to utilise both food and sexual deception. This included the observation and capture of potential pollinators of C. rigida through direct observation, pantraps, Malaise traps and pollinator-baiting experiments, and the use of molecular techniques to identify orchid pollinia isolated from carrier insects. We describe a suite of generalist insects visiting and bearing pollinia from C. rigida. In addition, s les collected from the labellum and column of C. rigida contained sugars at levels comparable to those of a known nectar-producing orchid, Microtis parviflora R.Br. Potential osmophores in the clubs and calli stained positively with neutral red and although this character is often associated with sexual deception, we found no evidence for this secondary pollination syndrome in C. rigida. The present study is the first one to provide a detailed description of the pollinators and pollination syndrome of a non-sexually deceptive species within the genus Caladenia and the first report to provide evidence of nectar production by a species within this genus.
Rooting theories of plant community ecology in microbial interactions
Publisher: Elsevier BV
Date: 08-2010
Effects of neighbouring vegetation on eucalypt seedlings at two sites subject to different levels of abiotic stress
Publisher: Wiley
Date: 05-03-2007
The combined effects of water and nitrogen on the relationship between a native hemiparasite and its invasive host
Publisher: Wiley
Date: 23-10-2020
DOI: 10.1111/NPH.16944
Abstract: Stem hemiparasites are dependent on their hosts for water and nitrogen. Most studies, however, have assessed the influence of one factor on parasite : host associations, thus limiting our mechanistic understanding of their performance in nature. We investigated the combined effects of water and nitrogen (N) availability on both a host ( Ulex europaeus ) and its parasite ( Cassytha pubescens ). Parasite infection significantly decreased host shoot biomass and shoot : root ratio more severely in high water than low water, irrespective of N supply. Parasite stem [N] was significantly higher in high water than low water treatments, regardless of N supply, but parasite biomass did not vary among treatments. Irrespective of water and N supply, infected plants had significantly lower total, root and nodule biomass, predawn and midday quantum yields, maximum electron transport rates, water potentials and nitrogen concentration [N]. Parasite δ 13 C was significantly higher than that of the host. Our results suggested that stem hemiparasites can better extract resources from hosts when water availability is high, resulting in a greater impact on the host under these conditions. When hemiparasitic plants are being investigated as a biocontrol for invasive weeds, they may be more effective in wetter habitats than in drier ones.
Related Organisations
Rutgers The State University Of New Jersey
Location: United States of America
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