Title: Enhanced litter input rather than changes in litter chemistry drive soil carbon and nitrogen cycles under elevated CO₂: a microcosm study

Author: Lui, Lingli; King, John S.; Booker, Fitzgerald L.; Giardina, Christian P.; Allen, H. Lee; Hu, Shuijin

Year: 2009

Publication: Global Change Biology. 15: 441-453.

Abstract: Elevated CO₂ has been shown to stimulate plant productivity and change litter chemistry. These changes in substrate availability may then alter soil microbial processes and possibly lead to feedback effects on N availability. However, the strength of this feedback, and even its direction, remains unknown. Further, uncertainty remains whether sustained increases in net primary productivity will lead to increased longterm C storage in soil. To examine how changes in litter chemistry and productivity under elevated CO₂ influence microbial activity and soil C formation, we conducted a 230-day microcosm incubation with five levels of litter addition rate that represented 0, 0.5, 1.0, 1.4 and 1.8 x litterfall rates observed in the field for aspen stand growing under control treatments at the Aspen FACE experiment in Rhinelander, WI, USA. Litter and soil samples were collected from the corresponding field control and elevated CO₂ treatment after trees were exposed to elevated CO₂ (560 ppm) for 7 years.