Tuesday, November 6, 2007
215-12
Annual and Cumulative Litter Decay in Clearcut, Closed Forest, and Wetland Sites Across Canada.
John A. Trofymow1, Erin Thompson2, Alan Cameron1, David Paré1, Mike Lavigne1, Larry Flanagan3, Tim Moore4, Brian Amiro5, Carolyn Smyth1, and Alice Solyma1. (1) Canadian Forest Service, 506 Burnside Rd. W, Victoria, BC V8Z 1M5, Canada, (2) Environment Canada, 11 Innovation Blvd, Saskatoon, SK S7N3H5, Canada, (3) University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada, (4) McGill University, 805 Sherbrooke St. West, Montreal, QC H3A 2K6, Canada, (5) University of Manitoba, Winnipeg, MB R3T 2N2, Canada
A litter decomposition study was established in 16 sites at 7 stations of the Fluxnet Canada Research Network. These sites included paired mature and clearcut forest sites at 5 upland stations (BC, SK, ON, QC, NB) as well as one site at each of two wetland stations (AW, QW) . All sites are instrumented for in situ measurements of soil moisture and temperature. Litterbags were prepared using one of four standard material types (aspen leaves -AL, black spruce needles BS, Douglas fir needles DF and birch wood sticks BW). Six replicate plots were located at each site, each plot contained sufficient numbers of surface litterbags of each material type to allow for four annual collections (2004 – 2007). As well unconfined birch chopsticks were placed at three depths down the soil profile (surface, 5cm, 15cm) and replaced annually to examine the effects of interannual variability on decay. Cumulative litter decay after three years litters ranked aspen<BS<DF<BW and most litters decay more in clearcut than forests, other than birchwood at one site (QC). Decay of surface birch sticks were similar and interannual variability was less than variability down the soil profile. The effects of clearcut varied with site, on wetter sites surface BW decayed faster in clearcuts than closed forest, however this was reversed in drier sites. At lower soil depths on drier sites, decay was more rapid in clearcuts than closed forest. Work is continuing to relate insitu microclimates to decay rates.