Fruit characteristics of invasive bitou bush, Chrysanthemoides monilifera (Asteraceae), and a comparison with co-occurring native plant species

Bitou bush, Chrysanthemoides monilifera (L.) Norlindh ssp. rotundata (DC.) Norlindh, is an invasive weed of coastal vegetation types in eastern Australia. It produces fleshy fruits, which are dispersed by birds and mammals. Compared with a range of vertebrate-dispersed fruits of native plant species that co-occur with naturalised C. monilifera, or occur elsewhere in south-eastern Australia, C. monilifera fruits and endocarps are intermediate in all dimensions and in the ratio of endocarp to pulp. C. monilifera fruits contain moderate quantities of sugars, but low quantities of protein and fat relative to many native fruits. Phenology, however, substantially distinguishes C. monilifera from co-occurring native plant species. C. monilifera produces fruits throughout the year, with the peak of production occurring in autumn to winter, a time when few native species in coastal vegetation produce fruits. Additionally, 9 of the 12 native species that do fruit, at least partly, over this period, differ substantially from C. monilifera in fruit morphology. C. monilifera, along with other invasive species, has substantially altered the temporal pattern of fruit availability in coastal vegetation. These fruiting characteristics have rendered C. monilifera fruits attractive to frugivores and have contributed to its successful spread.

Download Full-text

Emerging fungal pathogen of an invasive grass: Implications for competition with native plant species

PLoS ONE ◽

10.1371/journal.pone.0237894 ◽

2021 ◽

Vol 16 (3) ◽

pp. e0237894

Author(s):

Amy E. Kendig ◽

Vida J. Svahnström ◽

Ashish Adhikari ◽

Philip F. Harmon ◽

S. Luke Flory

Keyword(s):

Invasive Species ◽

Plant Species ◽

Fungal Pathogen ◽

Native Species ◽

Grass Species ◽

Leaf Spot Disease ◽

Native Plant ◽

Invasive Grass ◽

Native Plant Species ◽

Species Specific

Infectious diseases and invasive species can be strong drivers of biological systems that may interact to shift plant community composition. For example, disease can modify resource competition between invasive and native species. Invasive species tend to interact with a diversity of native species, and it is unclear how native species differ in response to disease-mediated competition with invasive species. Here, we quantified the biomass responses of three native North American grass species (Dichanthelium clandestinum, Elymus virginicus, and Eragrostis spectabilis) to disease-mediated competition with the non-native invasive grass Microstegium vimineum. The foliar fungal pathogen Bipolaris gigantea has recently emerged in Microstegium populations, causing a leaf spot disease that reduces Microstegium biomass and seed production. In a greenhouse experiment, we examined the effects of B. gigantea inoculation on two components of competitive ability for each native species: growth in the absence of competition and biomass responses to increasing densities of Microstegium. Bipolaris gigantea inoculation affected each of the three native species in unique ways, by increasing (Dichanthelium), decreasing (Elymus), or not changing (Eragrostis) their growth in the absence of competition relative to mock inoculation. Bipolaris gigantea inoculation did not, however, affect Microstegium biomass or mediate the effect of Microstegium density on native plant biomass. Thus, B. gigantea had species-specific effects on native plant competition with Microstegium through species-specific biomass responses to B. gigantea inoculation, but not through modified responses to Microstegium density. Our results suggest that disease may uniquely modify competitive interactions between invasive and native plants for different native plant species.

Download Full-text

Urban conservation gardening in the decade of restoration

10.32942/osf.io/p2syu ◽

2021 ◽

Author(s):

Ingmar Staude ◽

Josiane Segar ◽

Corey Thomas Callaghan ◽

Emma Ladouceur ◽

Jasper Meya ◽

...

Keyword(s):

Plant Species ◽

Native Species ◽

Species Conservation ◽

Plant Conservation ◽

Native Plant ◽

Nature Protection ◽

Urban Conservation ◽

Native Plant Species ◽

Native Seed ◽

Conservation Gardening

Global commitments to species conservation have failed to halt systematic widespread declines in plant species. Current policy interventions, such as protected areas and legal species legislation, remain insufficient, and there is an urgent need to engage novel approaches and actors in conservation. Here, we propose that urban conservation gardening, namely the cultivation of declining native plant species in public and private green spaces, can be one such approach. Conservation gardening can address key (a)biotic drivers of species decline, act as a critical dispersal pathway and increase the occupancy of declining native species. We identify policy mechanisms to upscale conservation gardening to a mainstream activity by reforming the existing horticultural market into an innovative nature protection instrument. This involves incentivizing the integration of the native seed sector, leveraging existing certification and labelling schemes, promoting consumer access, as well as building citizen-science projects to foster public engagement. Mainstreamed conservation gardening can be an economically viable, sustainable, and participatory measure that complements traditional approaches to plant conservation.

Download Full-text

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.

Download Full-text

Slash Pile Burn Scar Restoration: Tradeoffs between Abundance of Non-Native and Native Species

Forests ◽

10.3390/f11080813 ◽

2020 ◽

Vol 11 (8) ◽

pp. 813

Author(s):

Ian Sexton ◽

Philip Turk ◽

Lindsay Ringer ◽

Cynthia S. Brown

Keyword(s):

Plant Species ◽

Native Species ◽

Invasive Plant ◽

Chemical Properties ◽

Rocky Mountain ◽

Native Plant ◽

Burn Scar ◽

Native Plant Species ◽

Burned Areas ◽

Soil Scarification

The accumulation of live and dead trees and other vegetation in forests across the western United States is producing larger and more severe wildfires. To decrease wildfire severity and increase forest resilience, foresters regularly remove excess fuel by burning woody material in piles. This common practice could also cause persistent ecosystem changes such as the alteration of soil physical and chemical properties due to extreme soil heating, which can favor invasion by non-native plant species. The abundance and species richness of native plant communities may also remain depressed for many years after burning has removed vegetation and diminished propagules in the soil. This adds to the vulnerability of burned areas to the colonization and dominance by invasive species. Research into the use of revegetation techniques following pile burning to suppress invasion is limited. Studies conducted in various woodland types that investigated revegetation of pile burn scars have met with varying success. To assess the effectiveness of restoring pile burn scars in Rocky Mountain National Park, Colorado, we monitored vegetation in 26 scars, each about 5 m in diameter, the growing season after burning. Later that summer, we selected 14 scars for restoration that included soil scarification, seed addition, and pine duff mulch cover. We monitored the scars for four years, pre-restoration, and three years post-restoration and found that the cover of seeded species exceeded the surrounding unburned areas and unseeded controls. The restoration seeding suppressed cover of non-native species as well as native species that were not seeded during restoration. Our results suggest that restoration of pile burn scars could be a useful tool to retard the establishment of invasive plant species when there are pre-existing infestations near scars. However, this must be weighed against the simultaneous suppression of native species recruitment. Monitoring for periods more than three years will help us understand how long the suppression of native and non-native species by restoration species may persist.

Download Full-text

Tests of Hexazinone and Tebuthiuron for Control of Exotic Plants in Kauai, Hawaii

Forests ◽

10.3390/f10070576 ◽

2019 ◽

Vol 10 (7) ◽

pp. 576

Author(s):

Wang ◽

Awaya ◽

Zhu ◽

Motooka ◽

Nelson ◽

...

Keyword(s):

Invasive Plants ◽

Loblolly Pine ◽

Native Species ◽

Native Plants ◽

Early Period ◽

Metrosideros Polymorpha ◽

Native Plant ◽

Weed Species ◽

Invasive Weed ◽

Native Plant Species

Non-native plant species have become serious pests in Hawaii’s delicate island ecosystems. It is necessary to control invasive plants. The herbicides hexazinone and tebuthiuron were evaluated for defoliation efficacy to control several major invasive plants and for non-target effects on native plants at Site I in a rainforest at 1200 m elevation and Site II in a mesic area at 640 m elevation on the island of Kauai, Hawaii. The invasive weed species in the sites included daisy fleabane (Erigeron karvinskianus DC.), faya tree (Myrica faya Ait.), strawberry guava (Psidium cattleyanum Sabine), banana passion fruit (Passiflora mollissima Bailey), vaseygrass (Paspalum urvillei Steud.), and highbush blackberry (Rubus argutus Link. 1822). Native plants included ohia lehua (Metrosideros polymorpha Gaudich.), naupaka (Scaevola cerasifolia Labill.), pilo (Hedyotis mannii), hona (Urera glabra (Hook. & Arn.)), aalii (Dodonaea viscosa Jacq.), and amau (Sadleria sp.). The results showed that broadcast applications of hexazinone granules and tebuthiuron pellets were effective on some of those invasive species. Herbicidal tolerance varied among the native species. For example, D. viscosa showed high tolerance to hexazinone. S. cerasifolia was susceptible to hexazinone, but not to tebuthiuron. The inconsistent defoliation of Sadleria sp. occurred among different applications rates of the two herbicides. M. polymorpha, particularly when it was small, could tolerate hexazinone and tebuthiuron. U. glabra was severely injured by the two herbicides. H. mannii was moderately tolerant to hexazinone, but fairly sensitive to tebuthiuron. The invasive loblolly pine (Pinus taeda L.) was highly tolerant to hexazinone, but was very sensitive to tebuthiuron. M. faya was very sensitive to hexazinone, but very tolerant to tebuthiuron. P. cattleyanum was sensitive to both herbicides. Six and nine months after hexazinone and tebuthiuron treatment, respectively, native plants were transplanted into the Sites to observe injury from residual herbicides. Approximately less than 10% mortality was observed for the out-planted native species three months after planting (MAP), indicating that the native species showed less injury in the early period of transplant. The mortality of the three endangered species Kauai hau kuahiwi (Hibiscadelphis distans), Kauai delissea (Delissea rhytidosperma H.Mann) and kawawaenohu (Alsinidendron lynchnoides), however, increased as the MAP increased. Overall, broadcast treatments of hexazinone and tebuthiuron at rates higher than 1 kg active ingredient per hectare would be problematic. The dissipation half-life values of hexazinone and tebuthiuron in the 1-15 cm layer of soils at the two sites were approximately 7 days and greater than 180 days, respectively.

Download Full-text

Native plant species richness on Eastern Polynesia’s remote atolls

Progress in Physical Geography Earth and Environment ◽

10.1177/0309133315615804 ◽

2015 ◽

Vol 40 (1) ◽

pp. 112-134 ◽

Cited By ~ 1

Author(s):

Sébastien Larrue ◽

Jean-François Butaud ◽

Pascal Dumas ◽

Stéphane Ballet

Keyword(s):

Species Richness ◽

Sea Level ◽

Plant Species ◽

Native Species ◽

Abiotic Factors ◽

Plant Species Richness ◽

Native Plant ◽

Volcanic Island ◽

Native Plant Species ◽

Native Species Richness

Which abiotic factors influence the number of native plant species on remote atolls is an important question to understand better the spatial pattern of the species observed on these low and vulnerable coral islands. However, this issue is still very poorly documented, often due to human degradation, partial botanical surveys or the difficult geographic access of remote atolls for researchers. The remote atolls of Eastern Polynesia, which are among the most isolated in the world, are of great interest for studies of native species’ distribution due to their isolation, low human density and urbanisation. In this study, we selected 49 remote atolls of Eastern Polynesia with complete botanical surveys to test the relative influence of eight abiotic factors on native plant species richness (i.e. indigenous and endemic species). Abiotic factors used as potential predictors included atoll area (km2), shoreline length (km), atoll elevation (m) and index of isolation (UNEP), but also the coastal index of the atoll ( Ic), the distance to the nearest similar atoll (km), the distance to the nearest large volcanic island ≥ 1000 km2 (here, Tahiti as a potential stepping-stone island) and the distance to the nearest raised atoll ≥ 15 m a.s.l. (here, Makatea or Henderson as a potential refugium during sea-level highstands). Spearman’s rank correlation, linear regression analysis and frequency diagrams were used to assess the relative influence of these factors on native species richness. No relationship was found between the species richness and the index of isolation or the distance to the nearest similar atoll. Atoll area and distance to the nearest raised atoll of Makatea explained 47.1% and 40%, respectively, of the native species richness variation observed on the remote atolls. The distance to the volcanic island of Tahiti and the coastal index explained 36.9% and 27.3% of the variation, while elevation and shoreline length explained 23.3% and 18.4% of the variation, respectively. Native species richness on the atolls surveyed increased with the increasing atoll area, elevation and shoreline length, but decreased with the increasing distance to the nearest raised atoll of Makatea and the large volcanic island of Tahiti. This supports the view that the spatial pattern of native species richness observed on the remote atolls was strongly influenced by (i) atoll area but also by (ii) the distance to the raised atoll of Makatea, and (iii) the distance to the volcanic island of Tahiti. This finding suggests that the raised atoll may be viewed as a refugium during sea-level highstands while the large volcanic island played the role of stepping-stone island, both islands influencing the dispersal of native species on remote atolls and attenuating the isolation effect in the study area.

Download Full-text

Cheatgrass invasion alters the abundance and composition of dark septate fungal communities in sagebrush steppe

Botany ◽

10.1139/cjb-2015-0237 ◽

2016 ◽

Vol 94 (6) ◽

pp. 481-491 ◽

Cited By ~ 5

Author(s):

Catherine A. Gehring ◽

Michaela Hayer ◽

Lluvia Flores-Rentería ◽

Andrew F. Krohn ◽

Egbert Schwartz ◽

...

Keyword(s):

Community Composition ◽

Plant Species ◽

Mycorrhizal Fungi ◽

Native Species ◽

Invasive Plant ◽

Soil Microbial Communities ◽

Sagebrush Steppe ◽

Native Plant ◽

Native Plant Species ◽

Dark Septate Fungi

Invasive, non-native plant species can alter soil microbial communities in ways that contribute to their persistence. While most studies emphasize mycorrhizal fungi, invasive plants also may influence communities of dark septate fungi (DSF), which are common root endophytes that can function like mycorrhizas. We tested the hypothesis that a widespread invasive plant in the western United States, cheatgrass (Bromus tectorum L.), influenced the abundance and community composition of DSF by examining the roots and rhizosphere soils of cheatgrass and two native plant species in cheatgrass-invaded and noninvaded areas of sagebrush steppe. We focused on cheatgrass because it is negatively affected by mycorrhizal fungi and colonized by DSF. We found that DSF root colonization and operational taxonomic unit (OTU) richness were significantly higher in sagebrush (Artemisia tridentata Nutt.) and rice grass (Achnatherum hymenoides (Roem. & Schult.) Barkworth) from invaded areas than noninvaded areas. Cheatgrass roots had similar levels of DSF colonization and OTU richness as native plants. The community composition of DSF varied with invasion in the roots and soils of native species and among the roots of the three plant species in the invaded areas. The substantial changes in DSF we observed following cheatgrass invasion argue for comparative studies of DSF function in native and non-native plant species.

Download Full-text

The impacts of invasive plant species on the biodiversity of Australian rangelands

The Rangeland Journal ◽

10.1071/rj06014 ◽

2006 ◽

Vol 28 (1) ◽

pp. 27 ◽

Cited By ~ 58

Author(s):

A. C. Grice

Keyword(s):

Invasive Species ◽

Species Richness ◽

Plant Species ◽

Native Species ◽

Invasive Plant ◽

Plant Species Richness ◽

Native Plant ◽

Weed Species ◽

Ecological Processes ◽

Native Plant Species

Most parts of the Australian rangelands are at risk of invasion by one or more species of non-native plants. The severity of current problems varies greatly across the rangelands with more non-native plant species in more intensively settled regions, in climatic zones that have higher and more reliable rainfall, and in wetter and more fertile parts of rangeland landscapes. Although there is quantitative evidence of impacts on either particular taxonomic groups or specific ecological processes in Australian rangelands, a comprehensive picture of responses of rangeland ecosystems to plant invasions is not available. Research has been focused on invasive species that are perceived to have important effects. This is likely to down play the significance of species that have visually less dramatic influences and ignore the possibility that some species could invade and yet have negligible consequences. It is conceivable that most of the overall impact will come from a relatively small proportion of invasive species. Impacts have most commonly been assessed in terms of plant species richness or the abundance of certain groups of vertebrates to the almost complete exclusion of other faunal groups. All scientific studies of the impacts of invasive species in Australian rangelands have focused on the effects of individual invasive species although in many situations native communities are under threat from a complex of interacting weed species. Invasion by non-native species is generally associated with declines in native plant species richness, but faunal responses are more complex and individual invasions may be associated with increase, decrease and no-change scenarios for different faunal groups. Some invasive species may remain minor components of the vegetation that they invade while others completely dominate one stratum or the vegetation overall.

Download Full-text

Species diversity, composition and the regeneration potential of native plants at the Wainiveiota Mahogany Plantation, Viti Levu, Fiji Islands

The South Pacific Journal of Natural and Applied Sciences ◽

10.1071/sp12005 ◽

2012 ◽

Vol 30 (1) ◽

pp. 51 ◽

Cited By ~ 5

Author(s):

Senilolia H. Tuiwawa ◽

Gunnar Keppel

Keyword(s):

Plant Species ◽

Native Species ◽

Native Plants ◽

Line Transect ◽

Native Plant ◽

Regeneration Potential ◽

Native Plant Species ◽

Fiji Islands ◽

Lowland Rainforest ◽

Over Time

Mahogany (Swietenia macrophylla King) plantations cover a considerable area on the south-eastern parts of Viti Levu, Fiji. The understorey of these plantations often comprise a diverse, but undocumented, assemblage of native plant species. This study investigates the diversity, composition and regeneration potential of native plant species in the Wainiveiota mahogany plantation 40?50 years after establishment. Ten 10 m x 10 m plots were alternately placed at 10 m intervals perpendicular to a 200 m line transect. A total of 491 individual plants with dbh ≥ 1 cm, comprising 69 species, 51 genera and 34 families, were sampled. In addition to the exotic mahogany, there were 68 native (39 endemic, 24 indigenous and 5 identified to genus only) species recorded. Girronniera celtidifolia Gaud., Dillenia biflora (A.Gray) Martelli ex Dur. & Jacks and Barringtonia edulis Seem. had the highest recruitment and Endospermum macrophyllum (Muell.Arg.) Pax & Hoffm. was the dominant native species. Syzygium Gaertn. (Myrtaceae) was the most diverse genus and Myrtaceae the most diverse family. With 98% of the sapling recruitment consisting of native species, there is potential for re-establishment of a lowland rainforest dominated by native species over time.

Download Full-text

Effect of Competition from Native on Alien Species in a Multitrophic Setting

10.20944/preprints201910.0132.v1 ◽

2019 ◽

Author(s):

Eva Maria Malecore ◽

Mark van Kleunen

Keyword(s):

Alien Species ◽

Plant Species ◽

Native Species ◽

Niche Overlap ◽

Native Plant ◽

Closely Related Species ◽

Native Plant Species ◽

Phylogenetic Relatedness ◽

Multitrophic Interaction ◽

Target Plant

1. Darwin’s naturalization hypothesis predicts that alien species closely related to native species are less likely to naturalize because of strong competition due to niche overlap. Closely related species are likely to attract similar herbivores and to release similar plant volatiles following herbivore attack, thus could attract the same predators. However, the importance of phylogenetic relatedness on the interaction between alien and native plants has never been tested in a multitrophic context. 2. In a mesocosm experiment we grew six alien target plant species alone and in competition with nine native plant species of varying phylogenetic relatedness. To test the effects of multitrophic interactions on the performance of alien target species, we used enclosure cages to expose plants to the presence and absence of herbivorous arthropods, predatory arthropods and nematodes. 3. Surprisingly, biomass and number of flowering structures increased with presence of competitors for some of the alien species, but overall there was no consistent competition effect. Similarly, we found that none of the multitrophic-interaction treatments affected survival, biomass or number of flowering structures of the alien species. 4. We conclude there was no significant relationship between performance measures of the alien species and their phylogenetic relatedness to the native competitors.

Download Full-text