Experimental studies of seed predation in old-fields

Area of Science:

• Ecology
• Plant-Animal Interactions
• Community Ecology

Background:

• Post-dispersal seed predation significantly impacts plant population dynamics.
• Old-field habitats are crucial ecosystems supporting diverse plant and animal communities.
• Understanding seed removal rates is vital for predicting plant species success and distribution.

Purpose of the Study:

• To quantify seed loss rates to post-dispersal predators (ants and rodents) in old-field habitats.
• To investigate the influence of habitat type and seed density on predation.
• To determine if seed predators exhibit selective foraging behavior.

Main Methods:

• Field experiments in southwestern Michigan old-field habitats.
• Testing seed removal rates for 4-6 biennial plant species across varying densities and habitat types.
• Utilizing exclosure experiments to identify predator species and their seed preferences.

Main Results:

• Seed removal was significantly higher in vegetated habitats (1-20% daily loss) compared to disturbed soil.
• Rodents preferentially consumed larger seeds (e.g., Tragopogon dubius), while ants targeted smaller seeds.
• Seed density had a minimal effect on predation rates; predation was spatially patchy.

Conclusions:

• Post-dispersal seed predation is a significant factor in old-field ecosystems.
• Selective foraging by ants and rodents, coupled with spatially variable predation, influences the distribution and abundance of old-field herbs.
• Estimated seed loss rates are generally lower than in arid environments but can be substantial for certain species.