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Impact of human disturbance on bee pollinator communities in savanna and agricultural sites in Burkina Faso, West Africa - PubMed

  • ️Mon Jan 01 2018

. 2018 Jun 17;8(13):6827-6838.

doi: 10.1002/ece3.4197. eCollection 2018 Jul.

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Impact of human disturbance on bee pollinator communities in savanna and agricultural sites in Burkina Faso, West Africa

Katharina Stein et al. Ecol Evol. 2018.

Abstract

All over the world, pollinators are threatened by land-use change involving degradation of seminatural habitats or conversion into agricultural land. Such disturbance often leads to lowered pollinator abundance and/or diversity, which might reduce crop yield in adjacent agricultural areas. For West Africa, changes in bee communities across disturbance gradients from savanna to agricultural land are mainly unknown. In this study, we monitored for the impact of human disturbance on bee communities in savanna and crop fields. We chose three savanna areas of varying disturbance intensity (low, medium, and high) in the South Sudanian zone of Burkina Faso, based on land-use/land cover data via Landsat images, and selected nearby cotton and sesame fields. During 21 months covering two rainy and two dry seasons in 2014 and 2015, we captured bees using pan traps. Spatial and temporal patterns of bee species abundance, richness, evenness and community structure were assessed. In total, 35,469 bee specimens were caught on 12 savanna sites and 22 fields, comprising 97 species of 32 genera. Bee abundance was highest at intermediate disturbance in the rainy season. Species richness and evenness did not differ significantly. Bee communities at medium and highly disturbed savanna sites comprised only subsets of those at low disturbed sites. An across-habitat spillover of bees (mostly abundant social bee species) from savanna into crop fields was observed during the rainy season when crops are mass-flowering, whereas most savanna plants are not in bloom. Despite disturbance intensification, our findings suggest that wild bee communities can persist in anthropogenic landscapes and that some species even benefitted disproportionally. West African areas of crop production such as for cotton and sesame may serve as important food resources for bee species in times when resources in the savanna are scarce and receive at the same time considerable pollination service.

Keywords: bee communities; cotton; sesame; species spillover; sub‐Saharan Africa.

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Figures

Figure 1
Figure 1

Map with land‐use and land cover data of the three study areas Nazinga (low disturbance intensity; DI), Bontioli (medium DI), and Dano (high DI) in 2014 and their location within Burkina Faso

Figure 2
Figure 2

Mean total abundance (a), estimated species richness (bootstrap estimator) (b), and Pielou's species evenness (c) of bee communities caught with pan traps in savannas with low (Nazinga, n = 4), medium (Bontioli, n = 4), and high (Dano, n = 4) disturbance intensity (DI) in Burkina Faso during the dry and rainy season of 2014 and 2015. Different letters indicate significant differences between groups with p ≤ 0.05. Ordination of species composition (NMDS; d) is based on a sample size of 16 savannas, cotton and sesame fields each. NMDS stress value of 0.12 and goodness of the fit of R 2 = 0.99 (nonmetric)

Figure 3
Figure 3

Relationship between abundance (log‐transformed), species richness (bootstrap estimator), and Pielou's species evenness of bee communities sampled in ten savannas during the rainy season 2014 and adjacent cotton fields (black dots, straight line) and sesame fields (white dots) in Burkina Faso. Regression line indicates significant relationship between parameters with p ≤ 0.05 calculated using GLS with Gaussian correlation where necessary (Supporting Information Table S1)

Figure 4
Figure 4

Diversity components of bee species communities under different disturbance intensities (a) and result of ordination (NMDS) of bee communities sampled in savannas (white dots; stress: 0.12, nonmetric fit, R 2 = 0.99) and adjacent cotton (dark gray dots; stress: 0.19, nonmetric fit, R 2 = 0.96) and sesame fields (light gray dots; stress: 0.16, nonmetric fit, R 2 = 0.97) under low (b), medium (c), and high (d) disturbance intensity in 2014 and 2015 in Burkina Faso

Figure 5
Figure 5

Multiple line and scatter plot with error bars (median and 95% confidence interval) of bee abundance per month (data were standardized prior to analysis) at 12 savanna sites of 1 ha each (filled circles) and 11 cotton and 11 sesame fields (empty circles) in the Southwest of Burkina Faso. Only abundances of bee species occurring at both savanna sites and crop fields in each region were considered (low disturbance—Nazinga: Figure 5a,d; medium disturbance—Bontioli: Figure 5b,e; high disturbance—Dano: Figure 5c,f). Bee data from the cotton fields could only be collected during the rainy seasons of both years from June to September during the flowering period of the crop, as fields lay fallow during the rest of the year. Bee data in sesame fields were collected in 2015 only; hence, the spillover is only plotted for the sampling period in 2015. The sampling period for the savanna‐cotton spillover started in January 2014 (Jan14), for the savanna‐sesame spillover in January 2015 (Jan15)

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References

    1. Aizen, M. A. , & Harder, L. D. (2009). The global stock of domesticated honey bees is growing slower than agricultural demand for pollination. Current Biology, 19, 915–918. 10.1016/j.cub.2009.03.071 - DOI - PubMed
    1. Arbonnier, M. (2000). Arbres, arbustes et lianes des zones sèches d′Afrique de l′Ouest. Paris, France: CIRAD, MNHN, UICN.
    1. Archer, C. R. , Pirk, C. W. W. , Carvalheiro, L. G. , & Nicolson, S. W. (2014). Economic and ecological implications of geographic bias in pollinator ecology in the light of pollinator declines. Oikos, 123, 401–407. 10.1111/j.1600-0706.2013.00949.x - DOI
    1. Ashman, T. , Knight, T. M. , Steets, J. A. , Amarasekare, P. , Burd, M. , Campbell, D. R. , … Wilson, W. G. (2004). Pollen limitation of plant reproduction: Ecological and evolutionary causes and consequences. Ecology, 85, 2408–2421. 10.1890/03-8024 - DOI
    1. Basu, P. , Parui, A. K. , Chatterjee, S. , Dutta, A. , Chakraborty, P. , Roberts, S. , & Smith, B. (2016). Scale dependent drivers of wild bee diversity in tropical heterogeneous agricultural landscapes. Ecology and Evolution, 6, 6983–6992. 10.1002/ece3.2360 - DOI - PMC - PubMed

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