ISSN:
1573-5036
Keywords:
carbon
;
CO2 enrichment
;
nitrogen
;
particulate organic matter
;
roots
;
tallgrass prairie
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract We determined the effects of elevated [CO2] on the quantity and quality of below-ground biomass and several soil organic matter pools at the conclusion of an eight-year CO2 enrichment experiment on native tallgrass prairie. Plots in open-top chambers were exposed continuously to ambient and twice-ambient [CO2] from early April through late October of each year. Soil was sampled to a depth of 30 cm beneath and next to the crowns of C4 grasses in these plots and in unchambered plots. Elevated [CO2] increased the standing crops of rhizomes (87%), coarse roots (46%), and fibrous roots (40%) but had no effect on root litter (mostly fine root fragments and sloughed cortex material 〉500 μm). Soil C and N stocks also increased under elevated [CO2], with accumulations in the silt/clay fraction over twice that of particulate organic matter (POM; 〉53 μm). The mostly root-like, light POM (density ≤1.8 Mg m-3) appeared to turn over more rapidly, while the more amorphous and rendered heavy POM (density 〉1.8 Mg m-3) accumulated under elevated [CO2]. Overall, rhizome and root C:N ratios were not greatly affected by CO2 enrichment. However, elevated [CO2] increased the C:N ratios of root litter and POM in the surface 5 cm and induced a small but significant increase in the C:N ratio of the silt/clay fraction to a depth of 15 cm. Our data suggest that 8 years of CO2 enrichment may have affected elements of the N cycle (including mineralization, immobilization, and asymbiotic fixation) but that any changes in N dynamics were insufficient to prevent significant plant growth responses.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1004771805022
