Ecosystem services of pollinator diversity: a review of the relationship with pollen limitation of plant reproduction

Recent work on the ecosystem service of biodiversity suggests that higher pollinator diversity could lower pollen limitation, but these two aspects of plant-pollinator communities have only rarely been causally connected. Here we present a review of studies that produced quantitative assessments of both pollinator diversity and evenness as well as pollen limitation of focal plant species. Although pollen limitation is expected to be lower when pollinator diversity is high, our analysis suggests this relationship is weak. The relationship may be obscured when features of the plant species (e.g., average level of specialization) are confounded with features of the plant communities (e.g., habitat). We encourage researchers investigating pollen limitation to consider including measures of diversity of the floral visitors, and their effectiveness. These data would permit a more powerful test of the relationships among these variables and improve our understanding of the critical elements of stable plant-pollinator networks. Key words: ecosystem services, pollination, pollen, insects, flowering plants, pollinator diversity. Un travail recent sur les services rendus aux ecosystemes par la biodiversite suggere qu'une plus grande diversite de pollinisateurs pourrait reduire la limitation par le pollen, mais on a rarement etabli la relation de cause a effet de ces deux aspects de la relation plantes-pollinisateurs communautes. Les auteurs presentent une revue des etudes ayant produit des evaluations quantitatives a la fois de la diversite des pollinisateurs et l'uniformite et de la limitation par le pollen d'especes vegetales determinees. Bien que l'on s'attende a ce que la limitation par le pollen soit plus faible en presence d' une forte diversite de pollinisateurs, les auteurs constatent que cette relation est faible. La relation est possiblement masquee lorsque les particularites de l'espece vegetale (p. ex., degre moyen de specialisation) se confondent avec les particularites des communautes vegetales (p. ex., habitat). On encourage les chercheurs sur la limitation par le pollen a considerer des mesures inclusives de la diversite des visiteurs floraux, et leur efficacite. Ces donnees fourniraient une evaluation plus forte des relations entre ces variables et amelioreraient notre comprehension des elements critiques des reseaux stables plante-pollinisateur. Mots-cles : services aux ecosystemes, pollinisation, pollen, insectes, plantes a fleurs, diversite des pollinisateurs. [Traduit par la Redaction]
Introduction Pollen limitation (PL), the reduction in plant reproductive success as a result of inadequate quantity or quality of pollen deposition, is widespread among flowering plants. Previous reviews have calculated [...]