Exotic plants accumulate and share herbivores yet dominate communities via rapid growth

AbstractHerbivores may facilitate or impede exotic plant invasion, depending on their direct and indirect interactions with exotic plants relative to co-occurring natives. However, previous studies investigating direct effects have mostly used pairwise native-exotic comparisons with few enemies, reached conflicting conclusions, and largely overlooked indirect interactions such as apparent competition. Here, we ask whether native and exotic plants differ in their interactions with invertebrate herbivores. We manipulate and measure plant-herbivore and plant-soil biota interactions in 160 experimental mesocosm communities to test several invasion hypotheses. We find that compared with natives, exotic plants support higher herbivore diversity and biomass, and experience larger proportional biomass reductions from herbivory, regardless of whether specialist soil biota are present. Yet, exotics consistently dominate community biomass, likely due to their fast growth rates rather than strong potential to exert apparent competition on neighbors. We conclude that polyphagous invertebrate herbivores are unlikely to play significant direct or indirect roles in mediating plant invasions, especially for fast-growing exotic plants.

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Asymmetric pathogen spillover favors exotic plants over natives

10.22541/au.162064926.63740751/v1 ◽

2021 ◽

Author(s):

Lauren Waller ◽

Warwick Allen ◽

Amanda Black ◽

Jonathan Tonkin ◽

Jason Tylianakis ◽

...

Keyword(s):

Next Generation Sequencing ◽

Native Plants ◽

Exotic Plants ◽

Apparent Competition ◽

Pathogenic Microorganisms ◽

Indirect Benefit ◽

Plant Soil ◽

Soil Feedback ◽

Competitive Hierarchies ◽

Generation Sequencing

Exotic plants can escape from specialist pathogenic microorganisms in their new range, but may simultaneously accumulate generalist pathogens. This creates the potential for pathogen spillover, which could alter plant-competitive hierarchies via apparent competition. To assess the potential for and consequences of pathogen spillover in invaded communities, we conducted a community-level plant-soil feedback experiment in experimental communities that ranged in the extent of exotic dominance, using next-generation sequencing to characterize sharing of putatively-pathogenic, root-associated fungi (hereafter, ‘pathogens’). Exotic plants outperformed natives in communities, despite being subject to stronger negative plant-soil feedbacks in monoculture and harboring higher relative abundance of pathogens. Exotic plants made more general associations with pathogens, making them more prone to sharing pathogens with natives and exerting apparent competition. These data suggest that exotic plants accumulate generalist pathogens that are shared with native plants, conferring an indirect benefit to exotic, over native plants.

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Similarity in fine-to-total root mass ratio leads to comparative plant-soil feedbacks between co-occurring native and invasive plants

Journal of Plant Ecology ◽

10.1093/jpe/rtaa075 ◽

2020 ◽

Author(s):

Xuefei Tang ◽

Chunqiang Wei ◽

Lunlun Gao ◽

Bingbing Jia ◽

Xinmin Lu

Keyword(s):

Invasive Plants ◽

Plant Traits ◽

Plant Biomass ◽

Plant Invasions ◽

Soil Biota ◽

Root Mass ◽

Native Plant ◽

Mass Ratio ◽

Plant Soil

Abstract Aims Soil biota can affect plant-plant interactions and non-native plant invasions via plant-soil feedback (PSF). Understanding the drivers underlying interspecific variations in PSF is important for predicting the role of soil biota in non-native plant invasions. Recent studies found that PSF could be predicted by plant traits. The success of plant invasions is also linked with plant traits, suggesting a potential linkage between PSF and plant invasion via plant traits, but has not yet been tested. Here, we compared PSF between six phylogenetically-paired co-occurring native and invasive plants, and explored the potential linkage between PSF with plant root traits. Methods We conducted a two-phase PSF experiment. Field collected soils were conditioned by the six plant species for three months firstly, then seedlings of these plants were grown in living or sterilized soils that had been conditioned by conspecific vs. heterospecific (the congener/confamilial species) individuals. We estimated effects of biota in conspecific (con-specific PSF) or heterospecific (hetero-specific PSF) soils relative to sterilized soils, and the relative effects of biota in conspecific vs. heterospecific soils (PSF-away) on plant biomass. Important findings In general, soil biota suppressed plant growth, and there were no differences in con-specific PSF, hetero-specific PSF and PSF-away between native and invasive plants. PSF increased with rising plant fine-to-total root mass ratio in the presence of soil biota, and its value was comparable between native and invasive plants. Our results indicate that similarity in plant fine-to-total root mass ratio that predicted PSF may have partially led to the comparable PSFs between these native and invasive plants. Studies exploring the linkages among plant traits, PSF and plant invasions with more plants, in particular phylogenetically-distant plants, are needed to improve our understanding of the role of soil biota in plant invasions.

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Exotic vertebrate and invertebrate herbivores differ in their impacts on native and exotic plants: a meta-analysis

Biological Invasions ◽

10.1007/s10530-009-9622-1 ◽

2009 ◽

Vol 12 (2) ◽

pp. 407-419 ◽

Cited By ~ 30

Author(s):

Ayub M. O. Oduor ◽

José M. Gómez ◽

Sharon Y. Strauss

Keyword(s):

Meta Analysis ◽

Exotic Plants ◽

Invertebrate Herbivores

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Direct Biotic Plant–soil Feedback Promotes Dodonaea Viscosa Growth in a Dry-hot Valley, China

10.21203/rs.3.rs-316055/v1 ◽

2021 ◽

Author(s):

Xuemei Wang ◽

Bangguo Yan ◽

Liangtao Shi ◽

Gangcai Liu

Keyword(s):

Nutrient Cycling ◽

Soil Biota ◽

Shoot Biomass ◽

Total Biomass ◽

Conditioning Phase ◽

Dodonaea Viscosa ◽

Soil Sterilization ◽

Plant Soil ◽

Soil Feedback ◽

Feedback Phase

Abstract Biotic plant-soil feedback has been widely studied, and may be particularly important in resource-poor areas. However, the roles of soil nutrient cycling in affecting plant growth in this process still remained unclear. The aim of this study was to explore the roles of soil biota in regulating nutrient cycling by conducting a two-phase feedback experiment in a dry-hot valley, with a conditioning phase during which there were Dodonaea viscosa or no D. viscosa growing in the soil, and a feedback phase in which the effect of the conditioned soil biota on D. viscosa performance was measured. The growth of D. viscosa significantly reduced soil N after the conditioning phase. However, D. viscosa showed a positive plant-soil feedback. In the feedback phase, the D. viscosa conditioned soil promoted the stem diameter, leaf area, and leaf dry mass content of D. viscosa. Total biomass was also significantly higher in D. viscosa conditioned soil than that in not conditioned soil. In contrast, soil sterilization had a negative effect on the growth of D. viscosa, with a significant reduction in plant biomass, especially in D. viscosa conditioned soil, and soil sterilization significantly increased the root: shoot biomass ratio and litter mass. Furthermore, we showed that although the biota-driven changes in enzyme activities correlated with the leaf N and P amount especially P amount, the enzyme activity was not the main reason to promote D. viscosa growth in the conditioned soil.

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Conspecific and heterospecific plant–soil biota interactions of Lonicera japonica in its native and introduced range: implications for invasion success

Plant Ecology ◽

10.1007/s11258-021-01180-y ◽

2021 ◽

Author(s):

Md. N. Uddin ◽

Takashi Asaeda ◽

Animesh Sarkar ◽

Viraj P. Ranawakage ◽

Randall W. Robinson

Keyword(s):

Soil Biota ◽

Invasion Success ◽

Lonicera Japonica ◽

Plant Soil ◽

Introduced Range

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How direct and indirect non-native interactions can promote plant invasions, lead to invasional meltdown and inform management decisions.

Plant invasions: the role of biotic interactions ◽

10.1079/9781789242171.0153 ◽

2020 ◽

pp. 153-176

Author(s):

Sara E. Kuebbing

Keyword(s):

Native Species ◽

Native Plants ◽

Full Range ◽

Invasion Biology ◽

Apparent Competition ◽

Indirect Interactions ◽

Competitive Interactions ◽

Invasional Meltdown ◽

Soil Microbial ◽

Facilitative Interactions

Abstract In 1999, Daniel Simberloff and Betsy Von Holle introduced the term 'invasional meltdown'. The term and the concept have been embraced and critiqued but have taken a firm hold within the invasion biology canon. The original formulation of the concept argued two key points: first, biologists rarely study how non-natives interact with one another. Second, nearly all the conceptual models about the success and impact of invasive species are predicated on the importance of competitive interactions and an implicit assumption that non-natives should interfere with establishment, spread and impact of other non-natives. In response, Simberloff and Von Holle called for more research on invader interactions and proposed an alternative consequence of non-native species interactions - invasional meltdown - where facilitative interactions among non-natives could increase the invasion rate or ecological impacts in invaded systems. This chapter outlines the primary pathways in which direct and indirect interactions among non-natives could lead to invasional meltdown. It provides examples of how different types of interactions among non-natives could lead to net positive effects on the invasion success of non-native plants or the impact of non-native plants on invaded ecosystems. Direct effects are by far the most commonly explored form of non-native- non- native interaction, primarily focusing on plant mutualisms with pollinators, seed dispersers or soil microbial mutualists. There are, however, also examples of non-native plants that benefit from commensal and even herbivorous interactions with other non-natives. Indirect interactions among non-natives are very infrequently studied. Although examples are scarce, non-natives may indirectly benefit other non-native plants through trophic cascades, apparent competition and indirect mutualisms. It remains unclear whether indirect effects are important pathways to invasional meltdown. More work is needed on studying ecosystems that are invaded by multiple non-native species and we need to consider the full range of interactions among non-natives that could either stymie or promote their spread, population growth and impact. Only then can we address how common facilitative interactions are relative to competitive interactions among non-natives or provide robust suggestions on how to manage ecosystems.

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How a network approach has advanced the field of plant invasion ecology.

Plant invasions: the role of biotic interactions ◽

10.1079/9781789242171.0018 ◽

2020 ◽

pp. 324-339

Author(s):

Carine Emer ◽

◽

Sérgio Timóteo ◽

◽

Keyword(s):

Species Interactions ◽

Plant Invasion ◽

Native Species ◽

Invasion Biology ◽

Plant Invasions ◽

Network Approach ◽

Native Plant Species ◽

Functional Roles ◽

Network Approaches ◽

Plant Herbivore

Every organism on Earth, whether in natural or anthropogenic environments, is connected to a complex web of life, the famous 'entangled bank' coined by Darwin in 1859. Non-native species can integrate into local 'banks' by establishing novel associations with the resident species. In that context, network ecology has been an important tool to study the interactions of non-native species and the effects on recipient communities due to its ability to simultaneously investigate the assembly and disassembly of species interactions as well as their functional roles. Its visually appealing tools and relatively simple metrics gained momentum among scientists and are increasingly applied in different areas of ecology, from the more theoretical grounds to applied research on restoration and conservation. A network approach helps us to understand how plant invasions may or may not form novel species associations, how they change the structure of invaded communities, the outcomes for ecosystem functionality and, ultimately, the implications for the conservation of ecological interactions. Networks have been widely used on pollination studies, especially from temperate zones, unveiling their nested patterns and the mechanisms by which non-native plants integrate into local communities. Yet, very few papers have used network approaches to assess plant invasion effects in other systems such as plant-herbivore, plant-pathogen or seed-dispersal processes. Here we describe how joining network ecology with plant invasion biology started and how it has developed over the last few decades. We show the extent of its contribution, despite contradictory results and biases, to a better understanding of the role of non-native plant species in shaping community structure. Finally, we explore how it can be further improved to answer emerging questions.

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Exotic plant invasion and understorey species richness: a comparison of two types of eucalypt woodland in agricultural Western Australia

Pacific Conservation Biology ◽

10.1071/pc980021 ◽

1998 ◽

Vol 4 (1) ◽

pp. 21 ◽

Cited By ~ 10

Author(s):

Max Abensperg-Traun ◽

Lyn Atkins ◽

Richard Hobbs ◽

Dion Steven

Keyword(s):

Species Richness ◽

Exotic Species ◽

Plant Species ◽

Plant Invasion ◽

Native Plants ◽

Exotic Plants ◽

Exotic Plant ◽

Native Plant ◽

Road Verge ◽

Exotic Plant Invasion

Exotic plants are a major threat to native plant diversity in Australia yet a generic model of the invasion of Australian ecosystems by exotic species is lacking because invasion levels differ with vegetation/soil type and environmental conditions. This study compared relative differences in exotic species invasion (percent cover, spp. richness) and the species richness of herbaceous native plants in two structurally very similar vegetation types, Gimlet Eucalyptus salubris and Wandoo E. capillosa woodlands in the Western Australian wheatbelt. For each woodland type, plant variables were measured for relatively undisturbed woodlands, woodlands with >30 years of livestock grazing history, and woodlands in road-verges. Grazed and road-verge Gimlet and Wandoo woodlands had significantly higher cover of exotic species, and lower species richness of native plants, compared with undisturbed Gimlet and Wandoo. Exotic plant invasion was significantly greater in Gimlet woodlands for both grazed (mean 78% cover) and road-verge sites (mean 42% cover) than in comparable sites in Wandoo woodlands (grazed sites 25% cover, road-verge sites 19% cover). There was no significant difference in the species richness of exotic plants between Wandoo and Gimlet sites for any of the three situations. Mean site richness of native plants was not significantly different between undisturbed Wandoo and undisturbed Gimlet woodlands. Undisturbed woodlands were significantly richer in plant species than grazed and road-verge woodlands for both woodland types. Grazed and road-verge Wandoo sites were significantly richer in plant species than communities in grazed and road-verge Gimlet. The percent cover of exotics was negatively correlated with total (native) plant species richness for both woodland types (Wandoo r = ?0.70, Gimlet r = ?0.87). Of the total native species recorded in undisturbed Gimlet, 83% and 61% were not recorded in grazed and road-verge Gimlet, respectively. This compared with 40% and 33% for grazed and road-verge Wandoo, respectively. Grazed Wandoo and grazed Gimlet sites had significantly fewer native plant species than did road-verge Wandoo and road-verge Gimlet sites. Ecosystem implications of differential invasions by exotic species, and the effects of grazing (disturbance) and other factors influencing susceptibility to exotic plant invasion (landscape, competition and allelopathy) on native species decline are discussed. Exclusion of livestock and adequate methods of control and prevention of further invasions by exotic plants are essential requirements for the conservation of these woodland systems.

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