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High soil carbon dioxide concentrations inhibit root respiration of Douglas fir
Author(s) -
QI JINGEN,
MARSHALL JOHN D.,
MATTSON KIM G.
Publication year - 1994
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1994.tb02989.x
Subject(s) - respiration , carbon dioxide , zoology , chemistry , soil respiration , soil water , horticulture , respiration rate , gas analyzer , botany , environmental chemistry , biology , ecology , organic chemistry
summary Total and basal respiration ( R t and R b , respectively) of intact and undisturbed roots of one‐year‐old Douglas fir seedlings, Pseudotsuga menziesii var. glauca [Beissn] Franco, were measured at experimentally varied soil carbon dioxide concentrations ([CO 2 ]). Use of specially designed root boxes and a CO 2 gas‐flow compensating system designed around an infrared gas analyzer (IRGA) allowed controlled delivery of CO 2 to roots and simultaneous measurements of CO 2 released by roots. Root respiration rate responded to each inlet [CO 2 ], independent of whether the previous concentration had been higher or lower, within two to three hours (paired t test = 0.041, P = 0.622, and n = 13). Total and basal respiration rates decreased exponentially as soil [CO 2 ] rose from 130 ppm, well below atmospheric [CO 2 ], to 7015 ppm, a concentration not uncommon in field soils. Analyses of variance (ANOVA) showed that the effects of soil [CO 2 ] on rates of total and basal root respiration were statistically significant. Root respiration rates decreased by 4 to 5 nmol CO 2 g −1 dry weight of roots s −1 for every doubling of [CO 2 ] according to the following equations: ln( R 1 ) (nmol CO 2 g −1 s −1 ) = 5.24–0.30*ln[CO 2 ] with r = 0.78, P < 0.0001, and n = 70; and ln( R b ) (nmol CO 2 g −1 s −1 ) = 6.29–0.52 * ln[CO 2 ] with r = 0.82, P < 0.0001, and n = 35. The sensitivity of root respiration to [CO 2 ] suggests that some previous laboratory measurements of root respiration at atmospheric [CO 2 ], which is 3 to 10‐fold lower than [CO 2 ] in field soils, overestimated root respiration in the field. Further, the potential importance of soil [CO 2 ] indicates that it should be accounted for in models of below‐ground carbon budgets.