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Weed Ecology and Management

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Research - Landscape Position Effects on Weed Seed Predation

Weed seed predators are a significant source of weed mortality in agroecosystems, and as such provide an ecosystem service that may reduce the weed pressure experienced by farmers.  As part of a multi-tactic ecologically based weed management strategy, weed seed predation may reduce the need for herbicide application in conventional farming systems, and mechanical weed control in organic systems, mitigating the costs and negative environmental impacts of these practices.

Common seed predators in include mice and other small mammals, birds, and invertebrates including ants, crickets, and carabid beetles.  Postdispersal weed seed predation can be substantial, but is highly variable.  Seed predation is likely regulated by diverse and complex interacting factors including habitat characteristics within and adjacent to crop fields, space, and time.  Master’s student Sonja Birthisel is conducting research to compare the relative importance of these sources of variability to regulating seed predation rates.  Understanding these sources of variability is the first step toward our larger goal of helping farmers utilize this ecosystem service for seed predation on their farms.

Sample scheme: we placed a virtual grid over 21 acres of diverse crop and non-crop habitat at the Peacemeal Farm in Dixmont, ME.  Within each cell we randomly selected the latitude/longitude coordinates of one sample site, for a total of 240 sites.  This spatially explicit design allows us to measure the effect of space on seed predation.

Field assistant Krissy Birthisel measures Leaf Area Index.  At each sample site, we recorded the habitat type (crop, meadow, mowed grass, softwood forest, or riparian forest), and measured LAI and other habitat attributes to determine their effects on seed predation.

White throated sparrow feeding on one of our seed assays.  We installed two seed assays (dishes containing a know number of seeds) at each sample site to measure seed predation.  One was left open to all seed predators (shown).  The other was covered with a cage to exclude mammals and birds, allowing us to measure the contribution of invertebrates to total seed predation.

Image Description: Grid showing seed placement

Image Description: Field Assistant taking measurments

Image Description: Bird feeding on weed seeds

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Contact Information

Weed Ecology and Management
205 Roger Clapp Greenhouse
Orono, Maine 04469
Phone: 207.581.2933 | Fax: 207.581.2999E-mail:
The University of Maine
Orono, Maine 04469
A Member of the University of Maine System