HR: 0800h
AN: H51H-0864    [Abstracts]
TI: Moisture and Climatic Forcings on Sphagnum Productivity in a Cutover Peatland
AU: * Thompson, D K
EM: thompsdk@mcmaster.ca
AF: School of Geography and Earth Sciences, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
AU: Waddington, J M
EM: wadding@mcmaster.ca
AB: Gross ecosystem production (GEP) was measured at a sub-boreal ombotrophic peatland (Cacouna Bog) 15 km NE of Riviere-du-Loup, Quebec, in the summers of 2005 and 2006. The Cacouna bog was extensively mined between 1940 and 1970 using the block cut method. The combination of exposed, high bulk density peat and low water table (c. 30 cm) has produced a succession vegetation community of ericaceous shrubs, invasive trees, and only c. 10% Sphagnum moss cover. Chamber-based measurements were made at three locations arranged longitudinally along a cut trench. Volumetric water content (VWC) and temperature probes at four depths, tensiometers, and a meteorological station provided high temporal resolution moisture and climatic data. June to August precipitation in 2005 was 167 mm below the 30-year mean; in 2006, the deviation was only 17 mm below normal. The cool and dry summer of 2005 depressed VWC by 10-20 %, soil water tension by 20-40 mb, and maximum GEP by 5-10 g C m^-2 d^-1 as compared to 2006. Instantaneous GEP did not decline during prolonged rain-free periods in August 2005 where soil tensions exceeded –100 mb, within the hypothetical range of hyaline cell drainage and reduced GEP. The response of these Sphagnum cushions points to a resilience to hydrologic stress at intermediate age (35 years since establishment) not otherwise observed in younger Sphagnum cushions less than 5 years since establishment. These findings have implications on the parameterization of sensitivity to moisture stress in bog growth models, and to management of restored and naturally regenerating peatlands.
DE: 0428 Carbon cycling (4806)
DE: 0476 Plant ecology (1851)
DE: 0497 Wetlands (1890)
DE: 1813 Eco-hydrology
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: 2007 Fall Meeting