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Interactions between plant growth and soil nutrient cycling under elevated CO 2 : a meta‐analysis
Author(s) -
De GRAAFF MARIEANNE,
Van GROENIGEN KEESJAN,
SIX JOHAN,
HUNGATE BRUCE,
Van KESSEL CHRIS
Publication year - 2006
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 - 10.1111/j.1365-2486.2006.01240.x
Subject(s) - mineralization (soil science) , cycling , soil respiration , nutrient , carbon dioxide , soil carbon , nutrient cycle , ecosystem , agronomy , respiration , soil organic matter , biomass (ecology) , chemistry , environmental chemistry , organic matter , terrestrial ecosystem , carbon cycle , soil water , zoology , environmental science , botany , ecology , biology , soil science , forestry , organic chemistry , geography
Abstract free air carbon dioxide enrichment (FACE) and open top chamber (OTC) studies are valuable tools for evaluating the impact of elevated atmospheric CO 2 on nutrient cycling in terrestrial ecosystems. Using meta‐analytic techniques, we summarized the results of 117 studies on plant biomass production, soil organic matter dynamics and biological N 2 fixation in FACE and OTC experiments. The objective of the analysis was to determine whether elevated CO 2 alters nutrient cycling between plants and soil and if so, what the implications are for soil carbon (C) sequestration. Elevated CO 2 stimulated gross N immobilization by 22%, whereas gross and net N mineralization rates remained unaffected. In addition, the soil C : N ratio and microbial N contents increased under elevated CO 2 by 3.8% and 5.8%, respectively. Microbial C contents and soil respiration increased by 7.1% and 17.7%, respectively. Despite the stimulation of microbial activity, soil C input still caused soil C contents to increase by 1.2% yr −1 . Namely, elevated CO 2 stimulated overall above‐ and belowground plant biomass by 21.5% and 28.3%, respectively, thereby outweighing the increase in CO 2 respiration. In addition, when comparing experiments under both low and high N availability, soil C contents (+2.2% yr −1 ) and above‐ and belowground plant growth (+20.1% and+33.7%) only increased under elevated CO 2 in experiments receiving the high N treatments. Under low N availability, above‐ and belowground plant growth increased by only 8.8% and 14.6%, and soil C contents did not increase. Nitrogen fixation was stimulated by elevated CO 2 only when additional nutrients were supplied. These results suggest that the main driver of soil C sequestration is soil C input through plant growth, which is strongly controlled by nutrient availability. In unfertilized ecosystems, microbial N immobilization enhances acclimation of plant growth to elevated CO 2 in the long‐term. Therefore, increased soil C input and soil C sequestration under elevated CO 2 can only be sustained in the long‐term when additional nutrients are supplied.