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Root production and turnover and carbon budgets of two contrasting grasslands under ambient and elevated atmospheric carbon dioxide concentrations
Author(s) -
FITTER A. H.,
GRAVES J. D.,
WOLFENDEN J.,
SELF G. K.,
BROWN T. K.,
BOGIE D.,
MANSFIELD T. A.
Publication year - 1997
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 - 10.1046/j.1469-8137.1997.00804.x
Subject(s) - peat , carbon dioxide , gleysol , agronomy , biomass (ecology) , grassland , soil respiration , chemistry , respiration , nitrogen , zoology , soil water , environmental science , botany , biology , soil science , ecology , organic chemistry
summary Monoliths of two contrasting vegetation types, a species‐rich grassland on a brown earth soil over limestone and species‐poor community on a peaty gley, were transferred to solardomes and grown under ambient (350 μ 1 −1 ) and elevated (600 μ11 −1 ) CO 2 for 2 yr. Shoot biomass was unaltered but root biomass increased by 40–50% under elevated CO 2 . Root production was increased by elevated CO 2 in the peat soil, measured both as instantaneous and cumulative rates, but only the latter measure was increased in the limestone soil. Root growth was stimulated more at 6 cm depth than at 10 cm in the limestone soil. Turnover was faster under elevated CO 2 in the peat soil, but there was only a small effect on turnover in the limestone soil. Elevated CO 2 reduced nitrogen concentration in roots and might have increased mycorrhizal colonization. Respiration rate was correlated with N concentration, and was therefore lower in roots grown at elevated CO 2 . Estimates of the C budget of the two communities, based upon root production and on net C uptake, suggest that C sequestration in the peat soil increases by c. 0.2 kg C m −2 yr −1 (= 2 t ha yr −1 ) under elevated CO 2 .