Pollinator networks, alien species and the conservation of rare plants:Trinia glaucaas a case study

Abstract

Summary 1.Despite the essential role of pollination in the maintenance of many rare plant species, conservation management plans rarely consider the service of pollination. 2. This study identifies the main pollinators of a rare English plant species, Trinia glauca (Apiaceae), and provides recommendations for its conservation. A community-level approach is used, whereby a visitation network is constructed to identify the direct and indirect links between T. glauca and other members of the plant-visitor community. 3. A field experiment that excluded the main visitor species from female T. glauca showed that ants were the main pollinators of T. glauca . The network revealed that over the field season, 33% of the ants' visits to flowers were to alien plants, with Cotoneaster horizontalis making a particularly high contribution (58%) during the T. glauca flowering period. 4. The removal of alien plants is a part of the conservation management of T. glauca , and we simulated the likely consequences of this form of habitat management on T. glauca pollination, any effects being mediated by shared pollinators. Although positive or neutral effects are possible, a negative effect is also possible, whereby the removal of alien plants leads to a crash in ant populations, potentially reducing pollinator visits to T. glauca by up to 85·2%. 5. Synthesis and applications . Conserving the pollinators of rare plants is essential if their conservation is to be sustainable in the long term. Our data indicate that T. glauca is pollinated by ants and demonstrate that ants can also feed on alien plants, particularly during the flowering season of this rare plant. We suggest that management measures involving the removal of alien plants should consider the possible negative impacts on rare plants through changes in pollinator populations. In this case, a staged removal is likely to prove the best conservation approach, allowing the pollinators' response to be assessed before any serious negative effects occur.

Myophily in the critically endangered umbelliferous plant Ostericum palustre Besser (Apiaceae)

“…(Carvalheiro et al 2008). We also observed ants, in particular, individuals of M. rubra, visiting flowers of O. palustre.…”

“…Thysanoptera), and those insects smaller than 1 mm, were excluded from the analyses. Despite their well-documented inefficiency as pollinators (Puterbaugh 1998; Beattie and Hughes 2002), we did not exclude ants from our analysis, since recently, they have been reported to pollinate some umbelliferous plants (Carvalheiro et al 2008;Cursach and Rita 2012a, b).…”

“…However, even in the case of generalist species, their reproductive biology may be threatened by habitat fragmentation, as demonstrated for another endangered member of the family, namely, Seseli farrenyi Molero & Pujadas (Rovira et al 2004). Furthermore, in recent years, the pollination systems of a number of species of Apiaceae have been investigated, and these have proved to be less generalized than anticipated, exhibiting at least ecological and/or functional specialization (Lindsey 1984;Zych 2007;Carvalheiro et al 2008;Niemirski and Zych 2011). This may also be the case for O. palustre with profound effects on preservation of this rare species.…”

Indirect interactions between crops and natural vegetation through flower visitors: the importance of temporal as well as spatial spillover

“…For example, rare plant species have been found to rely on more common species via shared pollinators (Gibson et al, 2006), illustrating the importance to the system of species previously considered to be mere weeds. Similarly, rare plant species may also share pollinators with alien invasive species (Carvalheiro et al, 2008), and such knowledge can allow management to mitigate for the removal of alien species from the system while ensuring continued pollination of rare species.…”

Network topology of stable isotope interactions in a sub-arctic raptor guild

“…Unipartite projections of trophic interactions can hold useful information regarding intraguild processes, such as competition and facilitation among species (Miranda et al 2013), as well as ecosystem properties of consumer guilds (Dunne et al 2002;Jordán 2009). They may also aid in identifying ecologically important species (Jordán et al 2006) and to identify species most likely to be influenced by ecosystem perturbations such as biological invasions (Carvalheiro et al 2008). The relative importance of individual species can be quantified through centrality indices, which for trophic networks describe the number of other species with which a species share resources (Estrada 2007).…”