Monday, November 5, 2007
19-14

Earthworm abundances and distributions in endophyte- infected fescue pastures in northern Arkansas.

Ashley Rashe1, Mary C. Savin2, and Peter Tomlinson2. (1) Univ. of Arkansas CSES Club, RR5 Box 5220, Shell Knob, MO 65747, (2) Crop, Soil and Environmental Sciences Dept., University of Arkansas, 115 Plant Science Building, Fayetteville, AR 72701

The ecology of organisms that co-evolve within an ecosystem is likely to be distinct from that involving organisms recently introduced into an area. To better understand the relationship of exotic and native earthworms in endophyte-infected fescue, earthworm population sizes and distributions in tall fescue pastures were catalogued. Earthworms in two toxic and two novel endophyte-infected fescue fields in Fayetteville, Arkansas were sampled weekly from January through July in 2007. Each type of endophyte-infected pasture was established in 1997 and 2003. Sampling methods included a dig-and-sort approach and chemical extraction using a mustard solution. Although variable, sampling time was a significant factor in the number of worms collected. Earthworm abundances across all replicates and sampling times ranged from zero to 520 worms/m2. Maximum abundances decreased from 520 to 410 to 110 worms/m2 from the winter to spring to summer, respectively, showing a seasonal trend of declining numbers. Year of pasture establishment and type of fungal endophyte infection did not appear to impact earthworm abundances. Due to the low numbers of worms collected using mustard solution, chemical extraction was discontinued in May. Earthworms were identified to assess the diversity of native and exotic earthworms. Determining earthworm species may correlate to plant productivity and above and belowground quality of the site. Differentiation of worm populations among ecosystems may improve studies of how worms alter nutrient availability.

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