Effects of soil temperature on the carbon exchange of taiga seedlings.: I. Root respiration

• Published in: Canadian Journal of Forest Research
• Main Authors: Lawrence, William T., Oechel, Walter C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1983
• Subjects: taiga; Alaska
• Online Access: http://dx.doi.org/10.1139/x83-114; http://www.nrcresearchpress.com/doi/pdf/10.1139/x83-114

Seedlings of Alnuscrispa (Ait.) Pursh, Populusbalsamifera L., Populustremuloides Michx., and Betulapapyrifera Marsh., hardwood species of the taiga of interior Alaska, were grown in sand in a controlled environment room at day–night temperatures of 25 and 20 °C, respectively, with a 20-h day length. After establishment, pots containing each species were placed under soil-temperature treatments of 5, 15, and 25 °C while maintaining extant air-temperature and light regimes. Both total and maintenance respiration of the roots were measured under these temperature treatments by monitoring the efflux of CO 2 from the potted soil mass. An estimate of root-growth respiration was calculated as the difference between total and maintenance respiration. Total root respiration increased from three- to five-fold as soil temperature increased over the 20 °C experimental range. Growth-respiration response was species specific, occurring only at 5 °C soil temperature in A. crispa, at both 15 and 25 °C in P. balsamifera, and at all three soil temperatures in P. tremuloides. Growth respiration of the roots was a nearly constant fraction of total root respiration within a species, averaging 0.17 mg CO 2 •h −1 •g root dry weight −1 in A. crispa and P. balsamifera, but nearly twice that, 0.33 mg CO 2 •h −1 •g root dry weight −1 , in P. tremuloides. Growth respiration was not determined for B. papyrifera.