20 research outputs found
Response of soil biota to elevated atmospheric CO 2 in poplar model systems
We tested the hypotheses that increased belowground allocation of carbon by hybrid poplar saplings grown under elevated atmospheric CO 2 would increase mass or turnover of soil biota in bulk but not in rhizosphere soil. Hybrid poplar saplings ( Populus × euramericana cv. Eugenei) were grown for 5 months in open-bottom root boxes at the University of Michigan Biological Station in northern, lower Michigan. The experimental design was a randomized-block design with factorial combinations of high or low soil N and ambient (34 Pa) or elevated (69 Pa) CO 2 in five blocks. Rhizosphere microbial biomass carbon was 1.7 times greater in high-than in low-N soil, and did not respond to elevated CO 2 . The density of protozoa did not respond to soil N but increased marginally ( P  < 0.06) under elevated CO 2 . Only in high-N soil did arbuscular mycorrhizal fungi and microarthropods respond to CO 2 . In high-N soil, arbuscular mycorrhizal root mass was twice as great, and extramatrical hyphae were 11% longer in elevated than in ambient CO 2 treatments. Microarthropod density and activity were determined in situ using minirhizotrons. Microarthropod density did not change in response to elevated CO 2 , but in high-N soil, microarthropods were more strongly associated with fine roots under elevated than ambient treatments. Overall, in contrast to the hypotheses, the strongest response to elevated atmospheric CO 2 was in the rhizosphere where (1) unchanged microbial biomass and greater numbers of protozoa ( P  < 0.06) suggested faster bacterial turnover, (2) arbuscular mycorrhizal root length increased, and (3) the number of microarthropods observed on fine roots rose.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42279/1/442-113-2-247_81130247.pd
Interactive Effects of Atmospheric CO 2 and Soil-N Availability on Fine Roots of Populus tremuloides
GAS EXCHANGE, LEAF NITROGEN, AND GROWTH EFFICIENCY OFPOPULUS TREMULOIDESIN A CO2-ENRICHED ATMOSPHERE
Recommended from our members
Correspondence
Presents letters to the editor referencing articles and topics discussed in previous issues. "The Power of Pets," which discussed the passion of U.S. citizen for pets; "Not Two Cents," which focused on foreign policy writings by Thomas Friedman; "Kinder Cuts," which suggested the need for the U.S. administration to focus on balancing the budget and practicing fiscal responsibility