Effects of grazing intensity on pollinator abundance and diversity, and on pollination services

Lázaro, Amparo; Tscheulin, Thomas; Devalez, Jelle; Nakas, Georgios; Petanidou, Theodora

doi:10.1111/een.12310

Cited by 75 publications

(71 citation statements)

References 86 publications

(178 reference statements)

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“…As far as we know, this is the first study considering the degree of grazing instead of the qualitative description of the community as ungrazed vs. grazed (or highly grazed) to study changes in the structure plantflower visitor networks. In a previous study on the same communities (Lázaro et al, 2016), we found hump-shaped relationships between grazing intensity and the abundance and diversity for most flower visitor groups, and therefore, our general expectation is that intermediate grazing might increase the conservation value to plant-flower visitor networks in these sites. Specifically, we tested (1) whether intermediate grazing intensity increases the size, generalization, modularity, diversity, and evenness of interactions in the plantflower visitor networks, and (2) whether the number of interactions and selectiveness of different taxa in the networks changes with grazing intensity, particularly, whether at higher grazing intensities, ground-nesting bees increase number of interactions and decrease selectiveness compared to other bees.…”

Section: Moderation Is Best: Effects Of Grazing Intensity On Plant-flsupporting

confidence: 55%

“…In this area, sheep grazing (and to a lesser extent goat grazing) occurs throughout the year but is considerably more intense during spring. There is a large variability in the intensity of grazing among these sites, and we found hump-shaped relationships between grazing intensity and the abundance and diversity of plants and of most flower visitor groups in them (Lázaro et al, 2016).…”

Section: Study Sitesmentioning

confidence: 64%

“…4B). Fabaceae and Lamiaceae are visited mainly by bees which are more positively influenced by grazing compared to the other guilds (Lázaro et al, 2016); thus, an increase in the abundance of bees may result in a larger number of interactions in the species of these families. On the other hand, the strong decrease in the degree of Brassicaceae is related to a decrease in the abundance of this family as grazing intensity increased (slope: −11.04 ± 3.14; t = −3.52, P = 0.0004) and may reflect its susceptibility to grazing.…”

Section: Does Grazing Affect the Specialization Of Flower Visitor Andmentioning

confidence: 99%

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Moderation is best: effects of grazing intensity on plant-flower visitor networks in Mediterranean communities

Lázaro¹,

Tscheulin²,

Devalez³

et al. 2015

Ecological Applications

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Abstract. The structure of pollination networks is an important indicator of ecosystem stability and functioning. Livestock grazing is a frequent land use practice that directly affects the abundance and diversity of flowers and pollinators and, therefore, may indirectly affect the structure of pollination networks. We studied how grazing intensity affected the structure of plant-flower visitor networks along a wide range of grazing intensities by sheep and goats, using data from 11 Mediterranean plant-flower visitor communities from Lesvos Island, Greece. We hypothesized that intermediate grazing might result in higher diversity as predicted by the Intermediate Disturbance Hypothesis, which could in turn confer more stability to the networks. Indeed, we found that networks at intermediate grazing intensities were larger, more generalized, more modular, and contained more diverse and even interactions. Despite general responses at the network level, the number of interactions and selectiveness of particular flower visitor and plant taxa in the networks responded differently to grazing intensity, presumably as a consequence of variation in the abundance of different taxa with grazing. Our results highlight the benefit of maintaining moderate levels of livestock grazing by sheep and goats to preserve the complexity and biodiversity of the rich Mediterranean communities, which have a long history of grazing by these domestic animals.

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Section: Moderation Is Best: Effects Of Grazing Intensity On Plant-flsupporting

confidence: 55%

Section: Study Sitesmentioning

confidence: 64%

Section: Does Grazing Affect the Specialization Of Flower Visitor Andmentioning

confidence: 99%

See 1 more Smart Citation

Moderation is best: effects of grazing intensity on plant-flower visitor networks in Mediterranean communities

Lázaro¹,

Tscheulin²,

Devalez³

et al. 2015

Ecological Applications

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“…Grazing can impact bee communities indirectly through changes to the floral community (Lazaro et al. ). Often, grazing reduces the availability of floral resources, unlike fire which can increase floral density (Moranz et al.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, early season grazing has been shown to be harmful to bee communities because fewer resources are blooming during this time (Lazaro et al. ). We observed similar patterns among pastures used in this research.…”

Section: Discussionmentioning

confidence: 99%

Plant–pollinator networks in grassland working landscapes reveal seasonal shifts in network structure and composition

et al. 2019

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Declines in native bee populations can limit pollination services that support native plant communities and global food production. Mitigating the impacts on pollinators and ecosystems requires conservation actions that promote biodiversity and remain practical for producers. We investigated plantpollinator interaction networks in working grassland landscapes, managed for cattle production and biodiversity, to advance conservation of pollinators in grazed systems. We compared and plotted interactions at the network level. We then used a regression framework to evaluate the influence of floristic availability on pollinator abundance in our system. Overall, we detected seasonal shifts at the network level, with increased specialization between flowers and bees occurring at the end of the sampling season. Furthermore, the response to floristic resources differed between honey bees (Apis mellifera) and native bees. While honey bee abundance increased with exotic floral abundance, native bee abundance showed no relationship with floral abundance and instead was positively associated with floral richness in our system. These findings could be an indication of seasonal shifts in bee activity and interactions with plants or a response to the subset of available resources in grazed systems. These interpretations, along with the detected difference in resource use between honey bees and native bees, suggest foraging preferences differ between these two groups and could influence conservation and management strategies. Furthermore, it demonstrates a need to consider how management practices could influence bee communities differentially across the growing season and suggests conservation actions should promote native floristic resources to benefit native bees.

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Rangeland sharing by cattle and bees: moderate grazing does not impair bee communities and resource availability

Shapira

Henkin

Dag

et al. 2020

Ecological Applications

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Rangelands are a dominant anthropogenic land use and a main driver of natural habitat loss worldwide. Land sharing, the integration of agricultural production and biodiversity conservation, may provide a platform for managing rangelands to fulfill multiple ecosystem services. However, livestock grazing can greatly affect biodiversity and little is known about its effects on providers of focal ecosystem services, such as pollinators. We investigated the effect of cattle grazing on bee communities and their foraging and nesting resources in Mediterranean rangelands. Specifically, we explored the effect of moderate cattle grazing on flowering plant abundance, species richness and composition, the diversity of nesting substrates, and consequently, the possible effects on wild bee and honey bee foraging activity, species diversity, and community composition. We conducted field research in the Mediterranean rangelands of Israel during the main bee activity season, in the spring of 2012 and 2013, comparing paired cattle‐grazed and ungrazed areas. The availability of floral and nesting resources for bees was unaffected or positively affected by grazing. Similarly, wild bee abundance, species richness, and composition were not affected by grazing, but were instead shaped by spatiotemporal factors. Nor was honey bee activity level impaired by grazing. The foraging preferences of bees, as well as flower species composition and peak bloom differed between grazed and ungrazed areas. Therefore, in our studied rangelands, grazing had its main effect on the foraging choices of honey bees and wild bees, rather than on their abundance and diversity. Moreover, our results indicate the potentially important role of ungrazed patches in increasing nectar and pollen diversity and availability in rangelands for both honey bees and wild bees in the spring. Hence, maintaining a mosaic of moderately grazed and ungrazed patches is expected to provide the greatest benefits for wild bee conservation and honey bee activity in Mediterranean rangelands. Our findings support the notion of rangeland sharing by cattle and bees in Mediterranean ecosystems under moderate grazing intensities, mimicking the coexistence of honey bees, wild bees, and cattle in Mediterranean ecosystems on an evolutionary timescale.

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Effects of grazing intensity on pollinator abundance and diversity, and on pollination services

Cited by 75 publications

References 86 publications

Moderation is best: effects of grazing intensity on plant-flower visitor networks in Mediterranean communities

Moderation is best: effects of grazing intensity on plant-flower visitor networks in Mediterranean communities

Plant–pollinator networks in grassland working landscapes reveal seasonal shifts in network structure and composition

Rangeland sharing by cattle and bees: moderate grazing does not impair bee communities and resource availability

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