Positive effects of low grazing intensity on East African bee assemblages mediated by increases in floral resources

Lasway, Julius V.; Steffan‐Dewenter, Ingolf; Njovu, Henry K.; Kinabo, Neema R; Eardley, Connal; Pauly, Alain; Peters, Marcell K.

doi:10.1016/j.biocon.2022.109490

Cited by 7 publications

(15 citation statements)

References 65 publications

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“…Furthermore, this finding was supported by our results indicating that heavy grazing significantly reduced the seed set in plants receiving the open-pollinated treatment, but there was no significant difference in seed set between the control and moderate grazing plots. Understanding the mechanisms through which different grazing intensities may affect pollinator visiting is critical for informed management decisions and plant-pollinator conservation planning [35]. Our findings are important for understanding the effect of different grazing intensities on floral display, pollinator visits and the pollination success of C. microphylla.…”

Section: Plant Pollination Efficiency Under Different Grazing Intensi...mentioning

confidence: 80%

“…Grazing disturbance tends to decrease vegetation cover and plant height and changes to floral display can also reflect plant adaptation to grazing disturbance [4,23,34] Changes in pollinator richness with the intensity of livestock grazing was mediated by the effect of grazing on the floral resources [35]. Many studies have indicated that floral display may influence pollinator visitation frequency and the efficiency of resource transfer [16,21].…”

Section: Plant Pollination Efficiency Under Different Grazing Intensi...mentioning

confidence: 99%

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Effect of grazing disturbance on floral display, pollen limitation and plant pollination efficiency in the desert steppe

et al. 2022

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Background Grazing disturbance usually affects floral display and pollination efficiency in the desert steppe, which may cause pollen limitation in insect-pollinated plants. Effective pollination is essential for the reproductive success of insect-pollinated plants and insufficient pollen transfer may result in pollen limitation. Caragana microphylla Lam is an arid region shrub with ecological importance. Few studies have been conducted on how grazing disturbance influences pollen limitation and pollination efficiency of C. microphylla. Here, we quantify the effect of different grazing intensities on floral display, pollinator visitation frequency and seed production in the Urat desert steppe. Results In C. microphylla, supplemental hand pollination increased the seed set, and pollen limitation was the predominant limiting factor. As the heavy grazing significantly reduced the seed set in plants that underwent open-pollination, but there was no significant difference in the seed set between plants in the control plots and plants in the moderate grazing plots. Furthermore, there was a higher pollinator visitation frequency in plants in the control plots than in plants in the heavy grazing plots. Conclusions We found that pollinator visitation frequency was significantly associated with the number of open flowers. Our findings also demonstrated that seed production is associated with pollinator visitation frequency, as indicated by increased seed production in flowers with higher pollinator visitation frequency. Therefore, this study provides insight into the effect of different grazing intensities on floral display that are important for influencing pollinator visitation frequency and pollination efficiency in desert steppes.

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Section: Plant Pollination Efficiency Under Different Grazing Intensi...mentioning

confidence: 80%

Section: Plant Pollination Efficiency Under Different Grazing Intensi...mentioning

confidence: 99%

Effect of grazing disturbance on floral display, pollen limitation and plant pollination efficiency in the desert steppe

et al. 2022

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“…In each study site, all plant species visited by bees during random walks were recorded. This measure corresponds to the plant species used by foraging bees as an alternative to the assessment of the total number of plant species on sites (Classen et al, 2020; Lasway, Steffan‐Dewenter, et al, 2022; Tucker & Rehan, 2017). Plant species were recorded as bees visited blooms of flowering plants, that is, in case, we observed a bee walking or landing on a flower (not just flying over it) (Tucker & Rehan, 2017).…”

Section: Methodsmentioning

confidence: 99%

Agricultural intensification with seasonal fallow land promotes high bee diversity in Afrotropical drylands

Lasway

Peters

Njovu

et al. 2022

Journal of Applied Ecology

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The exponential increase in the human population in tandem with increased food demand has caused agriculture to be the global‐dominant form of land use. Afrotropical drylands are currently facing the loss of natural savannah habitats and agricultural intensification with largely unknown consequences for bees. Here we investigate the effects of agricultural intensification on bee assemblages in the Afrotropical drylands of northern Tanzania. We disentangled the direct effects of agricultural intensification and temperature on bee richness from indirect effects mediated by changes in floral resources. We collected data from 24 study sites representing three levels of management intensity (natural savannah, moderate intensive and highly intensive agriculture) spanning an extensive gradient of mean annual temperature (MAT) in northern Tanzania. We used ordinary linear models and path analysis to test the effects of agricultural intensity and MAT on bee species richness, bee species composition and body‐size variation of bee communities. We found that bee species richness increased with agricultural intensity and with increasing temperature. The effects of agricultural intensity and temperature on bee species richness were mediated by the positive effects of agriculture and temperature on the richness of floral resources used by bees. During the off‐growing season, agricultural land was characterized by an extensive period of fallow land holding a very high density of flowering plants with unique bee species composition. The increase in bee diversity in agricultural habitats paralleled an increasing variation of bee body sizes with agricultural intensification that, however, diminished in environments with higher temperatures. Synthesis and applications. Our study reveals that bee assemblages in Afrotropical drylands benefit from agricultural intensification in the way it is currently practiced. However, further land‐use intensification, including year‐round irrigated crop monocultures and excessive use of agrochemicals, is likely to exert a negative impact on bee diversity and pollination services, as reported in temperate regions. Moreover, several bee species were restricted to natural savannah habitats. To conserve bee communities and guarantee pollination services in the region, a mixture of savannah and agriculture, with long periods of fallow land should be maintained.

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“… Despite being used in the analysis of the research article by Lasway et al [1] , the dataset can also be used as a basis for decision making by policymakers, ecologists, and researchers interested in linking regional and global datasets to draw major conclusions. Using data on bees and associated forage resources [2] , ecologists can better understand bee-plant interaction networks under which generalist and specialist bee foragers can be identified.…”

Section: Value Of the Datamentioning

confidence: 99%

A dataset of occurrence of wild bees and their interaction with foraging plants along a livestock grazing gradient of northern Tanzania

et al. 2023

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Positive effects of low grazing intensity on East African bee assemblages mediated by increases in floral resources

Cited by 7 publications

References 65 publications

Effect of grazing disturbance on floral display, pollen limitation and plant pollination efficiency in the desert steppe

Effect of grazing disturbance on floral display, pollen limitation and plant pollination efficiency in the desert steppe

Agricultural intensification with seasonal fallow land promotes high bee diversity in Afrotropical drylands

A dataset of occurrence of wild bees and their interaction with foraging plants along a livestock grazing gradient of northern Tanzania

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