Canadian Forest Service Publications
Soil respiration responses to temperature are controlled more by roots than by decomposition in balsam fir ecosystems. 2003. Lavigne, M.B.; Boutin, R.; Foster, R.J.; Goodine, G.; Bernier, P.Y.; Robitaille, G. Canadian Journal of Forest Research 33: 1744-1753.
Issued by: Atlantic Forestry Centre
Catalog ID: 22975
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Concern exists that soil respiration (Rs) will increase with global warming, thereby reducing the sink strength of forest ecosystems for carbon (C) or making them sources. We measured Rs at three balsam fir (Abies balsamea (L.) Mill.) sites on a climatic gradient from 1997 to 2000 to assess potential responses to global warming. Mean annual Rs varied from 0.67 kg C.m-2.year-1 at the cool site, to 1.19 kg C.m-2.year-1 at the midtransect site, to 1.52 kg. C.m-2.year-1 at the warm site. Trenched plots were installed in 1999 to partition Rs into root respiration (Rr) and heterotrophic respiration (Rh). Differences in trenched-plot respiration (Rt) among sites were much less than differences in Rs, because trenching reduced Rs at the warm site more than at the cool site. Annual Rt was 22% less than annual Rs at the cool site, 36% less at the midtransect site, and 50% less at the warm site. After making adjustments for extraordinary decomposition of killed roots in trenched plots, it was estimated that annual Rh varied little among sites (0.40 kg C.m-2.year-1 at the cool site to 0.54 kg C.m-2.year-1 at the warm site), but annual Rt varied substantially among sites (0.24 kg C.m-2.year-1 at the cool site to 0.98 kg C.m-2.year-1 at the warm site). We conclude that Rs varied among sites, because climatically driven differences in primary productivity caused greater Rt and greater detrital production for Rh.