Flowering a week later is dearly bought off by lower reproductive success – What influences pollination success in a cultural landscape?

Janovský, Z. (1), Tomšová, P. (2), Horčičková, E. (1), Uhlíková, N. (3), Gruberová, P. (4), Kmecová, K. (5), Smyčka, J. (1), Řičařová, V. (1), Herben, T. (1,6)

1) Dept. of Botany, Faculty of Science, Charles University in Prague
2) Dept. of Ecosystem Biology, Faculty of Science, University of South Bohemia, České Budějovice
3) Secondary Grammar School of Johannes Keppler, Prague 6, Prague
4) Secondary Grammar School Klatovy, Klatovy
5) Secondary Grammar School Znojmo, Znojmo
6) Institute of Botany, Czech Academy of Sciences, Průhonice

Dramatic changes of agricultural practices during the 20th century have led to substantial changes in pollinator diversity and abundances in cultural landscape. Much attention has been paid to crops, but less is known about wild plants. We examined how changes in pollinator abundance affected reproduction biology of two relatively common wild plant species, Achillea ptarmica and A. millefolium. We focused on effects of site quality and position (meadow/road verge sites), time of flowering (beginning/middle/end of a one month long flowering season) and pollinator abundance on plant reproductive output, measured as seed production and germinability.

Both species are predominantly pollinated by hoverflies, whose abundance considerably declined during the plant flowering season. The path analysis of all predictors (as well as plant-size covariates) revealed that pollinator abundance was positively related to both reproductive output measures. After accounting for all direct and indirect effects the influence of pollinator abundance was approximately 2,5 times greater than the influence of site quality. The plants flowering at different times in season did not differ in any of their characteristics. The only influence of timing in the season was through pollinator abundance, which accounted for two thirds of the influence of pollinators.

We conclude that timing of flowering is the key factor in our system. Since it isn’t shaped only by plants themselves (and e.g. microclimatic conditions) but also by timing of hay cut, our work discovers an important and sensitive link between landscape management and plant population biology.

Presentováno na konferenci populačně biologické sekce Německé ekologické společnosti (GfÖ) konané v Tartu ve dnech 9.-11.5.2013.

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