The Origin and Distribution of Phytophthora Cinnamomi Rands in Australian Native Plant Communities and the Significance of Its Association With Particular Plant Species

This study examined the ability of foliar applications of the fungicide phosphite to contain colonisation of Phytophthora cinnamomi in a range of plant species growing in natural plant communities in the northern sandplain and jarrah (Eucalyptus marginata) forest of south-western Australia. Wound inoculation of plant stems with P. cinnamomi was used to determine the efficacy of phosphite over time after application. Colonisation by P. cinnamomi was reduced for 5–24 months after phosphite was applied, depending on the concentration of phosphite used, plant species treated and the time of phosphite application. Plant species within and between plant communities varied considerably in their ability to take up and retain phosphite in inoculated stems and in the in planta concentrations of phosphite required to contain P. cinnamomi. As spray application rates of phosphite increased from 5 to 20 g L–1, stem tissue concentrations increased, as did the ability of a plant species to contain P. cinnamomi. However, at application rates of phosphite above 5 g L–1 phytotoxicity symptoms were obvious in most species, with some plants being killed. So, despite 10 and 20 g L–1 of phosphite being more effective and persistent in controlling P. cinnamomi, these rates are not recommended for application to the plant species studied. The results of this study indicate that foliar application of phosphite has considerable potential in reducing the impact of P. cinnamomi in native plant communities in the short-term. However, in order to maintain adequate control, phosphite should be sprayed every 6–12 months, depending on the species and/or plant community.

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Competition between native and non-native plants.

Plant invasions: the role of biotic interactions ◽

10.1079/9781789242171.0016 ◽

2020 ◽

pp. 291-307

Author(s):

Elizabeth M. Wandrag ◽

◽

Jane A. Catford ◽

◽

...

Keyword(s):

Plant Species ◽

Plant Communities ◽

Native Species ◽

Abiotic Factors ◽

Invasion Biology ◽

Competitive Interactions ◽

Native Plant ◽

Native Plant Species ◽

New Locations ◽

Strength Of Competition

The introduction of species to new locations leads to novel competitive interactions between resident native and newly-arriving non-native species. The nature of these competitive interactions can influence the suitability of the environment for the survival, reproduction and spread of non-native plant species, and the impact those species have on native plant communities. Indeed, the large literature on competition among plants reflects its importance in shaping the composition of plant communities, including the invasion success of non-native species. While competition and invasion theory have historically developed in parallel, the increasing recognition of the synergism between the two themes has led to new insights into how non-native plant species invade native plant communities, and the impacts they have on those plant communities. This chapter provides an entry point into the aspects of competition theory that can help explain the success, dominance and impacts of invasive species. It focuses on resource competition, which arises wherever the resources necessary for establishment, survival, reproduction and spread are in limited supply. It highlights key hypotheses developed in invasion biology that relate to ideas of competition, outlines biotic and abiotic factors that influence the strength of competition and species' relative competitive abilities, and describes when and how competition between non-native and native plant species can influence invasion outcomes. Understanding the processes that influence the strength of competition between non-native and native plant species is a necessary step towards understanding the causes and consequences of biological invasions.

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Phytophthora cinnamomi invasion, a major threatening process to conservation of flora diversity in the South-west Botanical Province of Western Australia

Australian Journal of Botany ◽

10.1071/bt06019 ◽

2007 ◽

Vol 55 (3) ◽

pp. 225 ◽

Cited By ~ 101

Author(s):

B. L. Shearer ◽

C. E. Crane ◽

S. Barrett ◽

A. Cochrane

Keyword(s):

Plant Species ◽

Plant Communities ◽

Western Australia ◽

Phytophthora Cinnamomi ◽

Ex Situ ◽

Effective Control ◽

Susceptible Plant ◽

The South ◽

South West ◽

Indirect Impacts

The invasive soilborne plant pathogen Phytophthora cinnamomi Rands is a major threatening process in the South-west Botanical Province of Western Australia, an internationally recognised biodiversity hotspot. Comparatively recent introduction of P. cinnamomi into native plant communities of the South-west Botanical Province of Western Australia since the early 1900s has caused great irreversible damage and altered successional change to a wide range of unique, diverse and mainly susceptible plant communities. The cost of P. cinnamomi infestation to community values is illustrated by examination of direct (mortality curves, changes in vegetation cover) and indirect impacts on biodiversity and ecosystem dynamics, the proportion of Threatened Ecological Communities infested, Declared Rare Flora either directly or indirectly threatened by infestation and estimates of the proportion of the native flora of the South-west Botanical Province susceptible to the pathogen. While direct impacts of P. cinnamomi have been poorly documented in the South-west Botanical Province, even less attention has been given to indirect impact where destruction of the habitat by the pathogen affects taxa not directly affected by infection. Current poor understanding and quantification of indirect impacts of P. cinnamomi through habitat destruction results in an underestimation of the true impact of the pathogen on the flora of the South-west Botanical Province. Considerable variation of susceptibility to P. cinnamomi among and within families of threatened flora and responses of taxa within the genus Lambertia show how classification within family and genus are poor predictors of species susceptibility. Within apparently susceptible plant species, individuals are resistant to P. cinnamomi infection. Intra-specific variation in susceptibility can be utilised in the long-term management of threatened flora populations and needs to be a high research priority. Current control strategies for conservation of flora threatened by P. cinnamomi integrate hygiene and ex situ conservation with disease control using fungicide. Application of the fungicide phosphite has proven effective in slowing progress of P. cinnamomi in infested, threatened communities. However, variation in plant species responses to phosphite application is a major factor influencing effective control of P. cinnamomi in native communities. A greater understanding of the mechanisms of action of phosphite in plant species showing different responses to the fungicide may provide options for prescription modification to increase phosphite effectiveness in a range of plant species. The range of responses to P. cinnamomi infection and phosphite application described for Lambertia taxa suggests that the genus would make an ideal model system to elucidate the mechanisms of resistance to P. cinnamomi and the effectiveness of phosphite against the pathogen.

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Potential susceptibility of Australian native plant species to branch dieback and bole canker diseases caused by Phytophthora ramorum

Plant Pathology ◽

10.1111/j.1365-3059.2011.02513.x ◽

2011 ◽

Vol 61 (2) ◽

pp. 234-246 ◽

Cited By ~ 6

Author(s):

K. B. Ireland ◽

D. Hüberli ◽

B. Dell ◽

I. W. Smith ◽

D. M. Rizzo ◽

...

Keyword(s):

Plant Species ◽

Phytophthora Ramorum ◽

Native Plant ◽

Native Plant Species ◽

Australian Native Plant ◽

Branch Dieback

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Decoupled recovery of ecological communities after reclamation

PeerJ ◽

10.7717/peerj.7038 ◽

2019 ◽

Vol 7 ◽

pp. e7038 ◽

Cited By ~ 2

Author(s):

Zachary A. Sylvain ◽

David H. Branson ◽

Tatyana A. Rand ◽

Natalie M. West ◽

Erin K. Espeland

Keyword(s):

Plant Species ◽

Plant Communities ◽

Oil And Gas ◽

Plant Cover ◽

Reference Conditions ◽

Soil Conditions ◽

Ecological Communities ◽

Native Plant ◽

Ecosystem Recovery ◽

Nematode Communities

Grassland restoration is largely focused on creating plant communities that match reference conditions. However, these communities reflect only a subset of the biodiversity of grassland systems. We conducted a multi-trophic study to assess ecosystem recovery following energy development for oil and gas extraction in northern US Great Plains rangelands. We compared soil factors, plant species composition and cover, and nematode trophic structuring between reclaimed oil and gas well sites (“reclaims”) that comprise a chronosequence of two—33 years since reclamation and adjacent, undeveloped rangeland at distances of 50 m and 150 m from reclaim edges. Soils and plant communities in reclaims did not match those on undeveloped rangeland even after 33 years. Reclaimed soils had higher salt concentrations and pH than undeveloped soils. Reclaims had lower overall plant cover, a greater proportion of exotic and ruderal plant cover and lower native plant species richness than undeveloped rangeland. However, nematode communities appear to have recovered following reclamation. Although total and omni-carnivorous nematode abundances differed between reclaimed well sites and undeveloped rangeland, community composition and structure did not. These findings suggest that current reclamation practices recover the functional composition of nematode communities, but not soil conditions or plant communities. Our results show that plant communities have failed to recover through reclamation: high soil salinity may create a persistent impediment to native plant growth and ecosystem recovery.

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A century of ecosystem change: human and seabird impacts on plant species extirpation and invasion on islands

PeerJ ◽

10.7717/peerj.2208 ◽

2016 ◽

Vol 4 ◽

pp. e2208 ◽

Cited By ~ 6

Author(s):

Thomas K. Lameris ◽

Joseph R. Bennett ◽

Louise K. Blight ◽

Marissa Giesen ◽

Michael H. Janssen ◽

...

Keyword(s):

Species Richness ◽

Exotic Species ◽

Plant Species ◽

Plant Communities ◽

Soil Depth ◽

Rapid Change ◽

Ecosystem Change ◽

Native Plant ◽

Native Plant Species ◽

Species Cover

We used 116 years of floral and faunal records from Mandarte Island, British Columbia, Canada, to estimate the indirect effects of humans on plant communities via their effects on the population size of a surface-nesting, colonial seabird, the Glaucous-winged gull (Larus glaucescens). Comparing current to historical records revealed 18 extirpations of native plant species (32% of species historically present), 31 exotic species introductions, and one case of exotic introduction followed by extirpation. Contemporary surveys indicated that native species cover declined dramatically from 1986 to 2006, coincident with the extirpation of ‘old-growth’ conifers. Because vegetation change co-occurred with an increasing gull population locally and regionally, we tested several predictions from the hypothesis that the presence and activities of seabirds help to explain those changes. Specifically, we predicted that on Mandarte and nearby islands with gull colonies, we should observe higher nutrient loading and exotic plant species richness and cover than on nearby islands without gull colonies, as a consequence of competitive dominance in species adapted to high soil nitrogen and trampling. As predicted, we found that native plant species cover and richness were lower, and exotic species cover and richness higher, on islands with versus without gull colonies. In addition, we found that soil carbon and nitrogen on islands with nesting gulls were positively related to soil depth and exotic species richness and cover across plots and islands. Our results support earlier suggestions that nesting seabirds can drive rapid change in insular plant communities by increasing nutrients and disturbing vegetation, and that human activities that affect seabird abundance may therefore indirectly affect plant community composition on islands with seabird colonies.

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Biological nitrification inhibition by root exudates of native species,Hibiscus splendensandSolanum echinatum

PeerJ ◽

10.7717/peerj.4960 ◽

2018 ◽

Vol 6 ◽

pp. e4960 ◽

Cited By ~ 1

Author(s):

Chelsea K. Janke ◽

Laura A. Wendling ◽

Ryosuke Fujinuma

Keyword(s):

Plant Species ◽

Root Exudates ◽

Native Species ◽

N Uptake ◽

Nitrification Inhibition ◽

Native Plant ◽

Native Plant Species ◽

Potential Nitrification ◽

Australian Native Plant ◽

Biological Nitrification

Australian native species grow competitively in nutrient limited environments, particularly in nitrogen (N) limited soils; however, the mechanism that enables this is poorly understood. Biological nitrification inhibition (BNI), which is the release of root exudates into the plant rhizosphere to inhibit the nitrification process, is a hypothesized adaptive mechanism for maximizing N uptake. To date, few studies have investigated the temporal pattern and components of root exudates by Australian native plant species for BNI. This study examined root exudates from two Australian native species,Hibiscus splendensandSolanum echinatum,and contrasted with exudates ofSorghum bicolor, a plant widely demonstrated to exhibit BNI capacity. Root exudates were collected from plants at two, four, and six weeks after transplanting to solution culture. Root exudates contained three types of organic acids (OAs), oxalic, citric and succinic acids, regardless of the species. However, the two Australian natives species released larger amount of OAs in earlier development stages thanS. bicolor. The total quantity of these OAs released per unit root dry mass was also seven-ten times greater for Australian native plant species compared toS. bicolor. The root exudates significantly inhibited nitrification activity over six weeks’ growth in a potential nitrification assay, withS. echinatum(ca. 81% inhibition) >S. bicolor(ca. 80% inhibition) >H. splendens(ca. 78% inhibition). The narrow range of BNI capacity in the study plants limited the determination of a relationship between OAs and BNI; however, a lack of correlation between individual OAs and inhibition of nitrification suggests OAs may not directly contribute to BNI. These results indicate that Australian native species generate a strongly N conserving environment within the rhizosphere up to six weeks after germination, establishing a competitive advantage in severely N limited environments.

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Assessing antioxidant status during cryopreservation of Australian native plant species

Cryobiology ◽

10.1016/j.cryobiol.2016.09.029 ◽

2016 ◽

Vol 73 (3) ◽

pp. 405

Author(s):

B. Funnekotter ◽

E. Bunn ◽

R.L. Mancera

Keyword(s):

Plant Species ◽

Antioxidant Status ◽

Native Plant ◽

Native Plant Species ◽

Australian Native Plant

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Plant communities along the Eerste River, Western Cape, South Africa: Community descriptions and implications for restoration

Koedoe ◽

10.4102/koedoe.v55i1.1099 ◽

2013 ◽

Vol 55 (1) ◽

Cited By ~ 6

Author(s):

Clifton S. Meek ◽

Dave M. Richardson ◽

Ladislav Mucina

Keyword(s):

Ecosystem Services ◽

Plant Species ◽

Plant Communities ◽

Riparian Vegetation ◽

Riparian Zone ◽

Cape Floristic Region ◽

Conservation Value ◽

Western Cape ◽

Native Plant ◽

Alien Plant

Riparian plant communities fulfil many functions, including the provision of corridors linking protected areas and other zones of high conservation value. These habitats across much of South Africa’s Cape Floristic Region, especially in the lowlands, have been heavily impacted and degraded by human activities. There is increasing interest in the restoration of degraded riparian zones and the ecosystem services they provide to enhance the conservation value of landscapes. Previous studies of riparian vegetation in the Cape Floristic Region focused on pristine headwater systems, and little is known about human-impacted communities that make up most of the riparian vegetation in downstream areas. More information is needed on the composition of these plant communities to establish a baseline for management intervention. The riparian zone of the Eerste River in South Africa’s Western Cape province provides a good opportunity to study the features of riparian vegetation along the entire gradient, from pristine vegetation in a protected area through different levels of human-mediated degradation. Riparian vegetation was surveyed in 150 plots along the entire length of the Eerste River (ca. 40 km). Data were analysed using the vegetation classification and analysis software package JUICE. Final groupings were plotted onto a two-dimensional detrended correspondence analysis plane to check the position of the communities in the reduced multidimensional space. Ten distinct plant communities were identified, including several novel communities dominated by alien plant species. Descriptions of each plant community are presented. Diagnostic, constant and dominant species are listed and the major structural and ecological characteristics of each community are described.Conservation implications: Major changes to hydrological and soil properties, nutrient dynamics and disturbance regimes and plant species composition along sections of the riparian zone mean that restoration of many of these habitats to their historic condition is not feasible. However, several native plant species that provide key ecosystem services persist in and adjacent to transformed communities, offering substantial opportunities for restoration to achieve certain goals.

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