Plant-Pollinator Networks in Savannas of Burkina Faso, West Africa

Katharina Stein,Kathrin Stenchly,Stefan Porembski,Dethardt Goetze,Panagiotis Theodorou,Larba Hubert Balima,Karl Eduard Linsenmair,Drissa Coulibaly

doi:10.3390/d13010001

Abstract

West African savannas are severely threatened with intensified land use and increasing degradation. Bees are important for terrestrial biodiversity as they provide native plant species with pollination services. However, little information is available regarding their mutualistic interactions with woody plant species. In the first network study from sub-Saharan West Africa, we investigated the effects of land-use intensity and climatic seasonality on plant–bee communities and their interaction networks. In total, we recorded 5686 interactions between 53 flowering woody plant species and 100 bee species. Bee-species richness and the number of interactions were higher in the low compared to medium and high land-use intensity sites. Bee- and plant-species richness and the number of interactions were higher in the dry compared to the rainy season. Plant–bee visitation networks were not strongly affected by land-use intensity; however, climatic seasonality had a strong effect on network architecture. Null-model corrected connectance and nestedness were higher in the dry compared to the rainy season. In addition, network specialization and null-model corrected modularity were lower in the dry compared to the rainy season. Our results suggest that in our study region, seasonal effects on mutualistic network architecture are more pronounced compared to land-use change effects. Nonetheless, the decrease in bee-species richness and the number of plant–bee interactions with an increase in land-use intensity highlights the importance of savanna conservation for maintaining bee diversity and the concomitant provision of ecosystem services.

Highlights

Insect pollination is a key ecosystem service as the reproduction of many wild flowering plants depends on pollinating insects, especially bees [1,2]
We found that climate seasonality affected plant- and bee-species richness and their mutualistic network architecture
Community composition of bees and flowering plants did not differ between land-use intensity sites

Summary

Introduction

Insect pollination is a key ecosystem service as the reproduction of many wild flowering plants depends on pollinating insects, especially bees [1,2]. The effects of land-use intensity on flowering-plant and insect-pollinator communities may influence their interaction patterns, and the architecture of their mutualistic networks [8,9]. In addition to land-use change, climate seasonality in tropical regions may affect plant and bee diversity and further influence their mutualistic network architecture [10]. Network thinking has been integrated into conservation, restoration, and management [12,13] This integration offers promising tools to cope with the urgent challenge to understand and mitigate the effects of environmental change and species loss on crucial ecological processes such as pollination [14,15,16,17]. A review by Vizentin-Bugoni et al [18] highlights an uneven global distribution of plant–pollinator network studies biased towards nontropical areas

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