Plant-pollinator interactions in High Ardenne heathlands
(2017)
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- Authors
- Supervisors
- Jacquemart, Anne-Laure
- Abstract
- Evidence of pollinator decline has accumulated worldwide. The modifications of the landscape matrix like landscape use changes or destruction and degradation of habitats are factors explaining this decline. In this context, the aim of this study is to characterize the plant-pollinator interactions in a type of fragmented landscape, high Ardenne heathlands, and to analyse the effect of floral availability on the main pollinators. Particular attention was paid to the pairs of partners “ericaceous-bumblebee species” because they constitute the majority of interactions in heathlands. The originality of this thesis is to focus on plant-pollinator interactions during the whole flowering period, in a largely neglected biotope, with an interest in the conservation of both plant species and their pollinators. Interactions were described on the one hand based on plant point of view by measuring the relative importance of each visitor for plant pollination, and on the other hand, based on pollinator point of view, especially bumblebees, by studying the nutritional composition of collected floral resources. Influences of spatial and temporal variations of floral resources, from shrub scale to landscape scale, were taken into consideration. Our results show that abundance of the main pollinators, bumblebees, was determined by floral availability at the landscape scale (proportion of flower-rich biotopes) but not by heathland patch scale (heathland patch size). These results may be explained by movements of these generalist pollinators among landscape matrix components. Bumblebees collected pollen from heathland plant species (Ericaceae) from heathland edges (<i>Salix</i> x <i>multinervis</i>, <i>Cytisus scoparius</i>) and from surrounding biotopes (<i>Trifolium pratense</i> or <i>Filipendula ulmaria</i>). The proportion of different plant species in bumblebee diet and the fidelity for ericaceous species were not correlated with pollen composition i.e. polypeptide, amino acid and sterol concentrations. It reflected a multifactorial choice combining floral resource characteristics and the abundance and availability of these resources in the landscape. For example, the spruce plantation cover, a flower-poor biotope, was positively correlated with the abundance of the bumblebees visiting ericaceous flowers. The ericaceous species were visited more strongly when floral resources at the landscape scale were rare. Conversely, a negative correlation between the proportion of spruce plantations and the proportion of individuals collecting pollen on ericaceous species was observed. The reproductive success of the ericaceous species could be decreased in landscapes dominated by spruce plantations because the pollination effectiveness was dependent on the type of resource collected by visitors. By identifying effective pollinators, key plant species for pollinators and landscape factors influencing pollinator communities, the results of this thesis provide a basis for conserving plant-pollinator interactions in heathlands. Our results showed that the survival of ericaceous pollinators depends more on floral resource management at the landscape scale than the management of floral resources restricted to protected areas.
- Affiliations
UCLouvain SST/ELI/ELIA - Agronomy
Citations
Moquet, L. (2017). Plant-pollinator interactions in High Ardenne heathlands. https://hdl.handle.net/2078.5/180097