Litter inputs and plant interactions affect nectar sugar content
Article first published online: 1 FEB 2011
© 2011 The Authors. Journal of Ecology © 2011 British Ecological Society
Journal of Ecology
Volume 99, Issue 3, pages 828–837, May 2011
How to Cite
Baude, M., Leloup, J., Suchail, S., Allard, B., Benest, D., Mériguet, J., Nunan, N., Dajoz, I. and Raynaud, X. (2011), Litter inputs and plant interactions affect nectar sugar content. Journal of Ecology, 99: 828–837. doi: 10.1111/j.1365-2745.2011.01793.x
- Issue published online: 15 APR 2011
- Article first published online: 1 FEB 2011
- Received 19 May 2010; accepted 4 January 2011 Handling Editor: Sedonia Sipes
- above-ground–below-ground interactions;
- floral display;
- plant–plant interactions;
- plant–pollinator interactions;
- plant–soil interactions
1. Declines in availability of plant resources to pollinators are a major cause of pollinator loss. The management of plant communities to enhance floral resources is often proposed as a way to sustain pollinator populations. Nectar, the main energetic resource for pollinators, plays a central role in behaviour and composition of pollinator communities. Abiotic and biotic factors are known to influence nectar traits at both the species and community levels, but the impact of plant community composition itself has never been investigated.
2. Below-ground interactions in plant communities can induce changes in plant development through (i) plant-derived litter amendment of the soil and (ii) competition for soil resources between plants. We tested how plant below-ground interactions affect above-ground nectar traits involved in plant attractiveness to pollinators.
3. A short-term pot experiment was carried out with three temperate grassland species Mimulus guttatus, Lamium amplexicaule, and Medicago sativa, showing distinct litter stoichiometry and competitive abilities for soil resources. Litter amendment (none, mono and tri-specific litter) and plant interaction treatments (monocultures, two- and three-species mixtures) were crossed in a factorial design.
4. Litter amendment to the soil led to an increase in total nectar sugar content in L. amplexicaule plants but not in the two other species. We also found that the presence of M. guttatus, a competitive species, reduced the total nectar sugar content in L. amplexicaule through a concomitant decrease in nectar volume per flower and in floral display size, but not in other species. Species-specific responses of nectar traits to variation in soil nitrogen availability were thus observed, suggesting consequences for plant species and community attractiveness to pollinators. However, we did not find evidence that the legume M. sativa affected nectar traits of any neighbouring plants.
5. Synthesis. Our results demonstrate that litter inputs and competition between plants for soil resources can alter nectar traits linked to plant attractiveness to pollinators. This supports the idea that below-ground plant–plant interactions for soil resources can influence above-ground plant–plant interactions for pollination services. This offers promising perspectives in studying the role of below-ground–above-ground interactions on higher trophic levels.