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The influence of elevated atmospheric CO 2 on fine root dynamics in an intact temperate forest
Author(s) -
Pritchard Seth G.,
Rogers Hugo H.,
Davis Micheal A.,
Van Santen Edzard,
Prior Stephen A.,
Schlesinger William H.
Publication year - 2001
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1046/j.1354-1013.2001.00457.x
Subject(s) - temperate climate , ecosystem , environmental science , cycling , productivity , temperate forest , temperate rainforest , forest ecology , atmospheric sciences , horticulture , agronomy , chemistry , botany , ecology , biology , forestry , geology , macroeconomics , economics , geography
Root dynamics are important for plant, ecosystem and global carbon cycling. Changes in root dynamics caused by rising atmospheric CO 2 not only have the potential to moderate further CO 2 increases, but will likely affect forest function. We used FACE (Free‐Air CO 2 Enrichment) to expose three 30‐m diameter plots in a 13‐year‐old loblolly pine ( Pinus taeda ) forest to elevated (ambient + 200 µL L −1 ) atmospheric CO 2 . Three identical fully instrumented plots were implemented as controls (ambient air only). We quantified root dynamics from October 1998 to October 1999 using minirhizotrons. In spite of 16% greater root lengths and 24% more roots per minirhizotron tube, the effects of elevated atmospheric CO 2 on root lengths and numbers were not statistically significant. Similarly, production and mortality were also unaffected by the CO 2 treatment, even though annual root production and mortality were 26% and 46% greater in elevated compared to ambient CO 2 plots. Average diameters of live roots present at the shallowest soil depth were, however, significantly enhanced in CO 2 ‐enriched plots. Mortality decreased with increasing soil depth and the slopes of linear regression lines (mortality vs. depth) differed between elevated and ambient CO 2 treatments, reflecting the significant CO 2 by depth interaction. Relative root turnover (root flux/live root pool) was unchanged by exposure to elevated atmospheric CO 2 . Results from this study suggest modest, if any, increases in ecosystem‐level root productivity in CO 2 ‐enriched environments.