Vertical stratification of plant-pollinator interactions in a temperate grassland

Abstract

11Visitation of plants by different pollinators depends on individual plant traits, spatial context, and other factors. A neglected aspect of small-scale variation of plant-pollinator interactions is the role of vertical position of flowers. We conducted a series of experiments to study vertical stratification of plant-pollinator interactions in a dry grassland. We observed flower visitors on cut inflorescences of Centaurea scabiosa and Inula salicina placed at different heights above ground in two types of surrounding vegetation: short and tall. Even at such a small-scale, we detected significant shift in total visitation rate of inflorescences in response to their vertical position. In short vegetation, inflorescences close to the ground were visited more frequently, while in tall vegetation, inflorescences placed higher received more visits. Moreover, we found major differences in the composition of the pollinator community on flowers at different heights. In a second experiment, we measured flower visitation rate in inflorescences of Salvia verticillata of variable height. Total flower visitation rate increased markedly with inflorescence height in this case. Data on seed set of individual plants provide evidence for a corresponding positive pollinator-mediated selection on increased inflorescence height. Overall, our results demonstrate strong vertical stratification of plant-pollinator interactions at the scale of mere decimetres. This may have important ecological as well as evolutionary implications.

Does phenology explain plant–pollinator interactions at different latitudes? An assessment of its explanatory power in plant–hoverfly networks in French calcareous grasslands

“…Indeed, their generalist behaviour, at the species level, could be the result of individually specialized diets, since most pollen retrieved on hoverfly individuals usually comes from a single plant taxon (Lucas et al ) and depends on flower availability and phenology (Cowgill et al , Colley and Luna , Lucas et al ). Moreover, some hoverflies have preferences regarding plant colour, morphology and inflorescence height (Branquart and Hemptinne , Colley and Luna , Lunau , Klecka et al , b).…”

Are plants in sown flower strips suitable for communities of wild bees? Pollination network approach in conservation biology

“…This may be partly caused by identical seed mix used for sown flower strips at all sites. How-ever, the beta-diversity of pollinators may be affected also be affected by phenology (Carvell et al 2006, Ouvrard et al, 2018) and heterogeneity of vegetation structure because pollinators tend to modify their preferences for flowers based on the characteristics of vegetation such as the composition of surrounding flowers (Janovský et al 2013) or the height of the surrounding vegetation (Klečka et al 2018a). Despite variable mowing regimes, such structural patterns of the vegetation were still more variable in semi-natural habitats than in sown flower strips.…”

“…Increasing the floral diversity of the sown flower strips would likely lead to an increase of the diversity of solitary bees (Wood et al 2017) and other pollinators. Most pollinators display preferences for various floral traits, such as flower size, colour, and shape (Junker et al 2013, Klečka et al 2018b), or vegetation structure, such as plant height (Klečka et al 2018a) and spatial clustering (Janovský et al 2013, Blaauw & Isaacs 2014, Akter et al 2017). Increasing the functional diversity of plants in the sown flower strips and their microhabitat heterogeneity might have beneficial effects on pollinator communities by providing suitable conditions for a broader range of species and by decreasing their competition with dominant species such as Apis mellifera (Forup & Memmott 2005, Hudewenz & Klein 2013).…”

Factors affecting fruit and seed production of Paeonia ostii “Feng Dan”, an economically important oil tree

“…Flower number, plant height and flower size are also likely to be correlated with the overall resource status of individual plants (Hodgins & Barrett, 2008; Weiner, 1988). Many studies have demonstrated that fruit and seed production could increase with increasing flower number, plant height or mean flower size of individual plants (Andersson, 1991; de Jong, Waser, Price, & Ring, 1992; Klecka, Hadrava, & Koloušková, 2018; Mitchell, 1994; Ohara & Higashi, 1994; Ruane, Rotzin, & Congleton, 2014).…”