Thursday, May 29, 2008 - 3:45 PM
605

Leaf decomposition and benthic invertebrate colonization in summer-deployed leaf packs of japanese knotweed (Fallopia japonica), american sycamore (Platanus occidentalis), tulip poplar (Liriodendron tulipifera) and sugar maple (Acer saccharum)

Bruce Edinger1, Gregory J. Pond2, Margaret E. Passmore2, and Jedediah Robson1. (1) Natural Sciences and Mathematics, West Liberty State College, Campus Service Center #139, Route 88 North, West Liberty, WV 26074, (2) Environmental Assessment and Innovation Division, U.S. Environmental Protection Agency, 1060 Chapline St., Wheeling, WV 26003

Exotic Japanese knotweed invades riparian areas.  To evaluate whether knotweed litter may impact benthic invertebrate communities, 96 six-gram leaf packs were placed in a second order stream riffle to measure decomposition and invertebrate colonization.  After four regular intervals leaf packs were retrieved, invertebrates identified and leaves dried.  Leaf breakdown rate (k, negative slope of the linear regression of the loge of percent remaining leaf mass versus days of decay) was second highest for knotweed at 0.0379 (0.0134 for sycamore, 0.0268 for sugar maple and 0.0717 for tulip poplar).  Average total invertebrate abundance/pack after 15 days varied from 42.3 (tulip poplar) to 55.7 (knotweed), but species comparisons were not statistically significant (paired t-tests).  Thirty day total abundance averaged 83 individuals/pack overall; species comparisons lacked significance.  Average taxa richness/pack ranged from 17 to 20 after 30 days, but knotweed richness didn’t differ significantly from the other species.  After 15 days Gammarus (the dominant shredder) was twice as abundant in knotweed and sycamore than in maple and poplar leaf packs, but these differences moderated after 30 days.  Knotweed had the highest or near highest abundances of baetids, ephemerellids, leuctrids, hydropsychids, elmids and athericids, but not of empidids (these seven families and chironomids predominated).


Web Page: Japanese knotweed, decomposition, leaf pack

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