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Pollination, seed set and seed predation on a landscape scale
I Steffan-Dewenter1, U Münzenberg, T Tscharntke
1Agroecology, University of Göttingen, Waldweg 26, D-37073 Göttingen, Germany. isteffa@gwdg.de
Proceedings. Biological Sciences
|August 17, 2001
Summary
Landscape complexity impacts pollination and seed predation in Centaurea jacea. Increased landscape complexity boosted bee activity and seed predation, but not overall seed set, due to counterbalancing effects.
Area of Science:
- Ecology
- Pollination Biology
- Landscape Ecology
Background:
- Landscape structure influences ecological interactions.
- Pollination and seed predation are key factors affecting plant reproductive success.
- Understanding these interactions in complex landscapes is crucial for conservation.
Purpose of the Study:
- To investigate the combined effects of pollination and seed predation on the seed set of Centaurea jacea.
- To determine how landscape complexity, measured by semi-natural habitats, affects these interactions.
- To explore the spatial scales at which pollinators and seed predators respond to landscape structure.
Main Methods:
- Field study across 15 landscapes with varying structural complexity.
- Standardized measurements of flower visitation, seed predation, and seed set in Centaurea jacea patches.
- Analysis of landscape complexity at eight spatial scales (250-3000 m).
Main Results:
- Both bee visitation and seed predation increased with landscape complexity (proportion of semi-natural habitats).
- Overall seed set per flower head did not increase with landscape complexity, likely due to opposing pollination and predation effects.
- Seed set in undamaged heads correlated positively with flower visits, but landscape complexity did not directly correlate with seed set.
- Pollinator numbers responded to smaller landscape scales (up to 1000 m), while seed predators responded to larger scales (up to 2500 m).
Conclusions:
- The relationship between landscape complexity and plant reproductive success is complex, influenced by the balance between pollination and seed predation.
- Different species (honeybees vs. wild bees) and functional groups (pollinators vs. predators) perceive and respond to landscape structure at different spatial scales.
- Conservation strategies must consider these scale-dependent responses to effectively manage plant-pollinator and plant-herbivore interactions in heterogeneous landscapes.