Impact of Earthworm Activity on Weed Seed Bank Characteristics.

Earthworm burrowing and feeding can impact the soil seed bank, potentially influencing plant community composition. Specific impacts, however, depend on the size and ecological habit of the particular earthworm as well as the seed characteristics. Studies of the specific earthworms and weed species commonly found in Inland Pacific Northwest (IPNW) agroecosystems are lacking, and may lead to new, more ecologically based management approaches such as introducing particular earthworm species shown to be detrimental to specific weeds. Mesocosm experiments with endogeic (Aporrectodea trapezoides) and anecic (Lumbricus terrestris) species will be conducted.  Weed species of concern within the region will be selected for study and will include a diversity of seed size, shape and germination requirements.  The overall impact of earthworm burrowing and feeding activity on seed germination rates and seed burial will be discussed.