The role of plant-plant facilitation in non-native plant invasions.

Author(s):  
Lohegrin A. Cavieres ◽  
◽  

Biological invasions are one the most important drivers of the current environmental changes generating important biodiversity losses. Although several hypotheses have been proposed to understand the mechanisms underpinning biological invasions, most of them relate to negative interactions among native and invasive species, where the capacity for many invasive species to reduce diversity is often attributed to a greater competitiveness. However, neighbouring species can also show facilitative interactions, where the presence of one species can facilitate another directly by improving environmental conditions or indirectly through negative effects on a third party species. This chapter reviews the scientific literature on plant invasion, seeking examples of where facilitative interactions either among native and non-native plant species or among non-native species were demonstrated. There are several examples of native species that directly facilitate a non-native species, while examples of native species having a negative effect either on a native or a non-native species that compete with a target non-native, generating a net indirect facilitative effect of the native on the target non-native, are less numerous. Direct facilitation among non-native species has been reported as part of the 'invasional meltdown' phenomenon (Chapter 8, this volume). There are cases where non-native species can have a negative effect on a native species that competes with a target non-native, generating a net indirect facilitative effect among the non-natives. Finally, a non-native species can have a direct facilitative effect on native species, which might have important implications in restoration.

Author(s):  
Lohengrin A. Cavieres ◽  
◽  

Biological invasions are one the most important drivers of the current environmental changes generating important biodiversity losses. Although several hypotheses have been proposed to understand the mechanisms underpinning biological invasions, most of them relate to negative interactions among native and invasive species, where the capacity for many invasive species to reduce diversity is often attributed to a greater competitiveness. However, neighbouring species can also show facilitative interactions, where the presence of one species can facilitate another directly by improving environmental conditions or indirectly through negative effects on a third party species. This chapter reviews the scientific literature on plant invasion, seeking examples of where facilitative interactions either among native and non-native plant species or among non-native species were demonstrated. There are several examples of native species that directly facilitate a non-native species, while examples of native species having a negative effect either on a native or a non-native species that compete with a target non-native, generating a net indirect facilitative effect of the native on the target non-native, are less numerous. Direct facilitation among non-native species has been reported as part of the 'invasional meltdown' phenomenon (Chapter 8, this volume). There are cases where non-native species can have a negative effect on a native species that competes with a target non-native, generating a net indirect facilitative effect among the non-natives. Finally, a non-native species can have a direct facilitative effect on native species, which might have important implications in restoration.


Author(s):  
Lohengrin A. Cavieres

Abstract Biological invasions are one the most important drivers of the current environmental changes generating important biodiversity losses. Although several hypotheses have been proposed to understand the mechanisms underpinning biological invasions, most of them relate to negative interactions among native and invasive species, where the capacity for many invasive species to reduce diversity is often attributed to a greater competitiveness. However, neighbouring species can also show facilitative interactions, where the presence of one species can facilitate another directly by improving environmental conditions or indirectly through negative effects on a third party species. This chapter reviews the scientific literature on plant invasion, seeking examples of where facilitative interactions either among native and non-native plant species or among non-native species were demonstrated. There are several examples of native species that directly facilitate a non-native species, while examples of native species having a negative effect either on a native or a non-native species that compete with a target non-native, generating a net indirect facilitative effect of the native on the target non-native, are less numerous. Direct facilitation among non-native species has been reported as part of the 'invasional meltdown' phenomenon (Chapter 8, this volume). There are cases where non-native species can have a negative effect on a native species that competes with a target non-native, generating a net indirect facilitative effect among the non-natives. Finally, a non-native species can have a direct facilitative effect on native species, which might have important implications in restoration.


PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0237894
Author(s):  
Amy E. Kendig ◽  
Vida J. Svahnström ◽  
Ashish Adhikari ◽  
Philip F. Harmon ◽  
S. Luke Flory

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.


2006 ◽  
Vol 28 (1) ◽  
pp. 27 ◽  
Author(s):  
A. C. Grice

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.


2012 ◽  
Vol 18 (2) ◽  
pp. 123 ◽  
Author(s):  
E Reddy ◽  
D H Van Vuren ◽  
P G Scowcroft ◽  
J B Kauffman ◽  
L Perry

Seven exclosure sites located on Mauna Kea, Hawaii and established in the 1960s and 70s were sampled to characterize long-term response of the mamane (Sophora chrysophylla) forest to protection from feral sheep grazing, and to assess impacts of non-native plant species and recurrent sheep presence on forest recovery. The forest provides essential habitat for an endangered bird, the palila (Loxoides bailleui). Vegetation was sampled inside exclosures during 1972–1976, 1998, and 2009, and also outside exclosures during 2009. Patterns of response varied among exclosures, but overall, mamane trees and native shrubs showed increasing cover between the 1970s and 1998, then a slowed rate of increase in cover or a decline between 1998 and 2009. Cover of native herbaceous vegetation showed variable trends between the 1970s and 1998, and then appeared to decline between 1998 and 2009. Mamane height class distributions inside exclosures indicated that recruitment was initially high but then declined as heights shifted toward larger size classes, and presumably an older age distribution. We found limited evidence of a negative effect of non-native species on forest regrowth, but the effect was not consistent over time or among sites. Recurrent sheep presence outside exclosures negatively affected mamane canopy density and perhaps tree density at all sites, and mamane condition at some sites. Our results indicate that the mamane forest has shown substantial regrowth inside exclosures at some sites, especially those protected the longest. However, these exclosures represent a small portion of the mamane forest. Sheep presence continues to impact mamane recovery outside exclosures, and thus habitat quality for the palila.


2012 ◽  
Vol 5 (4) ◽  
pp. 494-505 ◽  
Author(s):  
Nicholas R. Jordan ◽  
Laura Aldrich-Wolfe ◽  
Sheri C. Huerd ◽  
Diane L. Larson ◽  
Gary Muehlbauer

AbstractDiversified grasslands that contain native plant species can produce biofuels, support sustainable grazing systems, and produce other ecosystem services. However, ecosystem service production can be disrupted by invasion of exotic perennial plants, and these plants can have soil-microbial “legacies” that may interfere with establishment and maintenance of diversified grasslands even after effective management of the invasive species. The nature of such legacies is not well understood, but may involve suppression of mutualisms between native species and soil microbes. In this study, we tested the hypotheses that legacy effects of invasive species change colonization rates, diversity, and composition of arbuscular-mycorrhizal fungi (AMF) associated with seedlings of co-occurring invasive and native grassland species. In a glasshouse, experimental soils were conditioned by cultivating three invasive grassland perennials, three native grassland perennials, and a native perennial mixture. Each was grown separately through three cycles of growth, after which we used T-RFLP analysis to characterize AMF associations of seedlings of six native perennial and six invasive perennial species grown in these soils. Legacy effects of soil conditioning by invasive species did not affect AMF richness in seedling roots, but did affect AMF colonization rates and the taxonomic composition of mycorrhizal associations in seedling roots. Moreover, native species were more heavily colonized by AMF and roots of native species had greater AMF richness (number of AMF operational taxonomic units per seedling) than did invasive species. The invasive species used to condition soil in this experiment have been shown to have legacy effects on biomass of native seedlings, reducing their growth in this and a previous similar experiment. Therefore, our results suggest that successful plant invaders can have legacies that affect soil-microbial associations of native plants and that these effects can inhibit growth of native plant species in invaded communities.


2021 ◽  
Author(s):  
Liping Shan ◽  
Ayub M.O. Oduor ◽  
Wei Huang ◽  
Yanjie Liu

Invasive plant species often exhibit greater growth and lower anti-herbivory defense than native plant species. However, it remains unclear how nutrient enrichment of invaded habitats may interact with competition from resident native plants to affect growth and defense of invasive plants. In a greenhouse experiment, we grew five congeneric pairs of invasive and native plant species under two levels of nutrient availability (low vs. high) that were fully crossed with simulated herbivory (clipping vs. no-clipping) and competition (alone vs. competition). Invasive plants produced more gibberellic acid, and grew larger than native species. Nutrient enrichment caused a greater increase in total biomass of invasive plants than of native plants, especially in the absence of competition or without simulated herbivory treatment. Nutrient enrichment decreased leaf flavonoid contents of invasive plants under both simulated herbivory conditions, but increased flavonoid of native plants under simulated herbivory condition. Nutrient enrichment only decreased tannins production of invasive species under competition. For native species, it enhanced their tannins production under competition, but decreased the chemicals when growing alone. The results indicate that the higher biomass production and lower flavonoids production in response to nutrient addition may lead to competitive advantage of invasive species than native species.


2015 ◽  
Vol 112 (14) ◽  
pp. 4387-4392 ◽  
Author(s):  
Chris D. Thomas ◽  
G. Palmer

Plants are commonly listed as invasive species, presuming that they cause harm at both global and regional scales. Approximately 40% of all species listed as invasive within Britain are plants. However, invasive plants are rarely linked to the national or global extinction of native plant species. The possible explanation is that competitive exclusion takes place slowly and that invasive plants will eventually eliminate native species (the “time-to-exclusion hypothesis”). Using the extensive British Countryside Survey Data, we find that changes to plant occurrence and cover between 1990 and 2007 at 479 British sites do not differ between native and non-native plant species. More than 80% of the plant species that are widespread enough to be sampled are native species; hence, total cover changes have been dominated by native species (total cover increases by native species are more than nine times greater than those by non-native species). This implies that factors other than plant “invasions” are the key drivers of vegetation change. We also find that the diversity of native species is increasing in locations where the diversity of non-native species is increasing, suggesting that high diversities of native and non-native plant species are compatible with one another. We reject the time-to-exclusion hypothesis as the reason why extinctions have not been observed and suggest that non-native plant species are not a threat to floral diversity in Britain. Further research is needed in island-like environments, but we question whether it is appropriate that more than three-quarters of taxa listed globally as invasive species are plants.


NeoBiota ◽  
2022 ◽  
Vol 71 ◽  
pp. 1-22
Author(s):  
Ming-Chao Liu ◽  
Ting-Fa Dong ◽  
Wei-Wei Feng ◽  
Bo Qu ◽  
De-Liang Kong ◽  
...  

Many studies have attempted to test whether certain leaf traits are associated with invasive plants, resulting in discrepant conclusions that may be due to species-specificity. However, no effort has been made to test for effects of species identity on invasive-native comparisons. Here, we compared 20 leaf traits between 97 pairs of invasive and native plant species in seven disturbed sites along a southwest-to-northeast transect in China using phylogenetically controlled within-study meta-analyses. The invasive relative to the native species on average had significantly higher leaf nutrients concentrations, photosynthetic rates, photosynthetic nutrients- and energy-use efficiencies, leaf litter decomposition rates, and lower payback time and carbon-to-nitrogen ratios. However, these differences disappeared when comparing weakly invasive species with co-occurring natives and when comparing invasives with co-occurring widespread dominant natives. Furthermore, the magnitudes of the differences in some traits decreased or even reversed when a random subset of strongly to moderately invasive species was excluded from the species pool. Removing rare to common natives produced the same effect, while exclusion of weakly to moderately invasives and dominant to common natives enhanced the differences. Our study indicates that the results of invasive-native comparisons are species-specific, providing a possible explanation for discrepant results in previous studies, such that we may be unable to detect general patterns regarding traits promoting exotic plant invasions through multi-species comparisons.


2021 ◽  
Author(s):  
Alexander Goetz ◽  
Ian Moffit ◽  
Anna A. Sher

Abstract Invasive species removal is a common focus in restoration ecology, but the ultimate goal of native plant species recovery and habitat recovery is often elusive. Control of invasive Tamarix spp. shrubs in the American Southwest has only sometimes led to increased native species cover; this is of particular concern for the protection of the endangered Southwestern willow flycatcher (Empidonax extimus trailii, abbr. SWFL) that nests readily in Tamarix when native Salix canopy is absent. If we can identify the conditions that lead to more native trees as well as habitat protection for the SWFL, we can prioritize restoration efforts more effectively and reduce conflict between conservation goals. To determine whether reduction in the invasive Tamarix led to more Salix cover (and thus no net loss in SWFL habitat), we compiled data on vegetation, soils, and geographic conditions in 260 sites where Tamarix had been subject to control efforts and 132 positive and negative reference sites. We found that (1) reduction in Tamarix only increased Salix cover in wetter sites, and was greater when a particular, low-disturbance removal method was used; however the increase did not typically compensate for the overall losses in canopy cover, and (2) Salix cover was generally highest in locations with low drought stress, as reflected by soil properties, distance to water, and climate. These results suggest that the presence and recovery of Salix is dependent on its relatively narrow environmental niche, in contrast with Tamarix’s broader one. Thus, although abundance of Salix and Tamarix was negatively correlated, this is likely because of Salix’s different niche, as much as or more than direct interspecific competition. Our findings demonstrate that removal of an invasive species does not necessarily lead to reestablishment of the native species they appeared to displace. We suggest that in the case of promoting habitat for SWFL and other birds, outcomes of restoration activity can be improved by focusing Tamarix removal efforts on sites more likely to promote Salix growth based on environmental characteristics.


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