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Direct and Indirect Influence of Non-Native Neighbours on Pollination and Fruit Production of a Native Plant.

Montero-Castaño A, Vilà M - PLoS ONE (2015)

Bottom Line: Overall, Hedysarum increased pollinator visitation rates to Leopoldia target plants as a result of direct and indirect effects acting in the same direction.Due to its floral display, Hedysarum exerted a direct magnet effect attracting visits to native target plants, especially those made by the honeybee.Hedysarum overall also increased the fructification of Leopoldia target plants, even though such an increase was the result of other indirect effects compensating for the observed negative indirect effect mediated by the decrease of floral diversity.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Ecología Integrativa, Estación Biológica de Doñana (EBD), Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain.

ABSTRACT

Background: Entomophilous non-native plants can directly affect the pollination and reproductive success of native plant species and also indirectly, by altering the composition and abundance of floral resources in the invaded community. Separating direct from indirect effects is critical for understanding the mechanisms underlying the impacts of non-native species on recipient communities.

Objectives: Our aims are: (a) to explore both the direct effect of the non-native Hedysarum coronarium and its indirect effect, mediated by the alteration of floral diversity, on the pollinator visitation rate and fructification of the native Leopoldia comosa and (b) to distinguish whether the effects of the non-native species were due to its floral display or to its vegetative interactions.

Methods: We conducted field observations within a flower removal experimental setup (i.e. non-native species present, absent and with its inflorescences removed) at the neighbourhood scale.

Results: Our study illustrates the complexity of mechanisms involved in the impacts of non-native species on native species. Overall, Hedysarum increased pollinator visitation rates to Leopoldia target plants as a result of direct and indirect effects acting in the same direction. Due to its floral display, Hedysarum exerted a direct magnet effect attracting visits to native target plants, especially those made by the honeybee. Indirectly, Hedysarum also increased the visitation rate of native target plants. Due to the competition for resources mediated by its vegetative parts, it decreased floral diversity in the neighbourhoods, which was negatively related to the visitation rate to native target plants. Hedysarum overall also increased the fructification of Leopoldia target plants, even though such an increase was the result of other indirect effects compensating for the observed negative indirect effect mediated by the decrease of floral diversity.

No MeSH data available.


Neighbourhood treatments.The non-native Hedysarum is represented in black and the native species, whether Leopoldia or others, are represented in grey. Target Leopoldia plants are represented inside dashed squares. Arrows represent the different comparisons done to assess the overall effect of Hedysarum (A); the effects mediated by Hedysarum floral display (B); and the effects due to Hedysarum vegetative parts (vegetative interaction) (C).
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pone.0128595.g002: Neighbourhood treatments.The non-native Hedysarum is represented in black and the native species, whether Leopoldia or others, are represented in grey. Target Leopoldia plants are represented inside dashed squares. Arrows represent the different comparisons done to assess the overall effect of Hedysarum (A); the effects mediated by Hedysarum floral display (B); and the effects due to Hedysarum vegetative parts (vegetative interaction) (C).

Mentions: Within the 1 m radius around Leopoldia target plants we randomly established three neighbourhood treatments according to the presence of Hedysarum: (i) Control, Hedysarum plants absent; (ii) Invaded, Hedysarum flowering plants present; and (iii) Removal, Hedysarum plants with clipped inflorescences but intact vegetative parts present (Fig 2). Overall, there were 14 Leopoldia target plants without non-native neighbours (Control); 11 Leopoldia target plants with Hedysarum individuals in their neighbourhoods (Invaded) and 18 Leopoldia target plants with manually clipped Hedysarum inflorescences in their neighbourhood (Removal). Clipping was conducted as often as it was necessary, usually every 3–4 days, in order to ensure that no new inflorescences were able to bloom during the sampling season. Hedysarum cover did not differ between Invaded and Removal treatments (N = 29, t = -0.171, P-value = 0.866). The presence and abundance of the other floral resources in the neighbourhood, including non-target Leopoldia individuals, were not manipulated in any of the treatments.


Direct and Indirect Influence of Non-Native Neighbours on Pollination and Fruit Production of a Native Plant.

Montero-Castaño A, Vilà M - PLoS ONE (2015)

Neighbourhood treatments.The non-native Hedysarum is represented in black and the native species, whether Leopoldia or others, are represented in grey. Target Leopoldia plants are represented inside dashed squares. Arrows represent the different comparisons done to assess the overall effect of Hedysarum (A); the effects mediated by Hedysarum floral display (B); and the effects due to Hedysarum vegetative parts (vegetative interaction) (C).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482463&req=5

pone.0128595.g002: Neighbourhood treatments.The non-native Hedysarum is represented in black and the native species, whether Leopoldia or others, are represented in grey. Target Leopoldia plants are represented inside dashed squares. Arrows represent the different comparisons done to assess the overall effect of Hedysarum (A); the effects mediated by Hedysarum floral display (B); and the effects due to Hedysarum vegetative parts (vegetative interaction) (C).
Mentions: Within the 1 m radius around Leopoldia target plants we randomly established three neighbourhood treatments according to the presence of Hedysarum: (i) Control, Hedysarum plants absent; (ii) Invaded, Hedysarum flowering plants present; and (iii) Removal, Hedysarum plants with clipped inflorescences but intact vegetative parts present (Fig 2). Overall, there were 14 Leopoldia target plants without non-native neighbours (Control); 11 Leopoldia target plants with Hedysarum individuals in their neighbourhoods (Invaded) and 18 Leopoldia target plants with manually clipped Hedysarum inflorescences in their neighbourhood (Removal). Clipping was conducted as often as it was necessary, usually every 3–4 days, in order to ensure that no new inflorescences were able to bloom during the sampling season. Hedysarum cover did not differ between Invaded and Removal treatments (N = 29, t = -0.171, P-value = 0.866). The presence and abundance of the other floral resources in the neighbourhood, including non-target Leopoldia individuals, were not manipulated in any of the treatments.

Bottom Line: Overall, Hedysarum increased pollinator visitation rates to Leopoldia target plants as a result of direct and indirect effects acting in the same direction.Due to its floral display, Hedysarum exerted a direct magnet effect attracting visits to native target plants, especially those made by the honeybee.Hedysarum overall also increased the fructification of Leopoldia target plants, even though such an increase was the result of other indirect effects compensating for the observed negative indirect effect mediated by the decrease of floral diversity.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Ecología Integrativa, Estación Biológica de Doñana (EBD), Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain.

ABSTRACT

Background: Entomophilous non-native plants can directly affect the pollination and reproductive success of native plant species and also indirectly, by altering the composition and abundance of floral resources in the invaded community. Separating direct from indirect effects is critical for understanding the mechanisms underlying the impacts of non-native species on recipient communities.

Objectives: Our aims are: (a) to explore both the direct effect of the non-native Hedysarum coronarium and its indirect effect, mediated by the alteration of floral diversity, on the pollinator visitation rate and fructification of the native Leopoldia comosa and (b) to distinguish whether the effects of the non-native species were due to its floral display or to its vegetative interactions.

Methods: We conducted field observations within a flower removal experimental setup (i.e. non-native species present, absent and with its inflorescences removed) at the neighbourhood scale.

Results: Our study illustrates the complexity of mechanisms involved in the impacts of non-native species on native species. Overall, Hedysarum increased pollinator visitation rates to Leopoldia target plants as a result of direct and indirect effects acting in the same direction. Due to its floral display, Hedysarum exerted a direct magnet effect attracting visits to native target plants, especially those made by the honeybee. Indirectly, Hedysarum also increased the visitation rate of native target plants. Due to the competition for resources mediated by its vegetative parts, it decreased floral diversity in the neighbourhoods, which was negatively related to the visitation rate to native target plants. Hedysarum overall also increased the fructification of Leopoldia target plants, even though such an increase was the result of other indirect effects compensating for the observed negative indirect effect mediated by the decrease of floral diversity.

No MeSH data available.