Effects of hydrologic changes on aboveground production and surface water chemistry in two boreal peatlands in Alberta: Implications for global warming |
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Authors: | Thormann Markus N Bayley Suzanne E Szumigalski Anthony R |
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Institution: | (1) Department of Biological Sciences, CW-405, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada;(2) #339, 78 College Avenue West, Guelph, Ontario, N1G 4S7, Canada |
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Abstract: | Aboveground net primary production (NPP) and surface water chemistryvariables were monitored in a lacustrine sedge fen and
a bog for four years.There were no significant differences in precipitation, mean growing seasonannual temperature, and number
of growing degree days from 1991 to 1994. Themean annual water levels in the lacustrine sedge fen differed significantly,whereas
they were similar in the bog during these four years. We measured 15surface water variables in the lacustrine sedge fen and
the bog, and foundthat only two correlated significantly with water level fluctuations. In thelacustrine sedge fen, calcium
correlated positively (r2= 0.56) and nitrate correlated negatively (r2 =0.20) with water levels. In the bog, potassium correlated positively(r2 = 0.88) and total dissolved phosphorus correlatednegatively (r2 = 0.62) with water levels. The remainingchemical variables showed no significant correlations with water levelfluctuations.
Net primary production of the different vegetation strataappeared to respond to different environmental variables. In the
lacustrinesedge fen, graminoid production was explained to a significant degree bywater levels (r2 = 0.53), whereas shrub production wasexplained to a significant degree by surface water chemistry variables, suchas nitrate
(r2 = 0.74) and total phosphorus(r2 = 0.22). In the bog, temperature was the onlyvariable that explained moss production to a significant degree(r2 = 0.71), whereas ammonium explained graminoidproduction (r2 = 0.66) and soluble reactive phosphorusexplained shrub production to significant degrees (r2 =0.71). There are few direct data on the impact of climatic warming in borealwetlands, although paleoecological and 2×CO2 model datahave provided some indications of past and possibly future changes invegetation composition, respectively. Our
results suggest that thelacustrine sedge fen may succeed to a bog dominated by Sphagnum spp. andPicea mariana, whereas the
bog may succeed to an upland-type forestecosystem.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | bog fen water levels aboveground plant production surface water chemistry global warming |
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