Title: Chemistry and decomposition of litter from Populus tremuloides Michaux grown at elevated atmospheric CO₂and varying N availability

Author: King, John S.; Pregitzer, Kurt S.; Zak, Donald R.; Kubiske, Mark E.; Ashby, Jennifer A.; Holmes, William E.

Year: 2001

Publication: Global change biology. Vol. 7 (2001).:p. 65-74.

Abstract: It has been hypothesized that greater production of total nonstructural carbohydrates (TNC) in foliage grown under elevated atmospheric carbon dioxide (CO₂) will result in higher concentrations of defensive compounds in tree leaf litter, possibly leading to reduced rates of decomposition and nutrient cycling in forest ecosystems of the future. To evaluate the effects of elevated atmospheric CO₂ on litter chemistry and decomposition, we performed a 111 day laboratory incubation with leaf litter of trembling aspen (Populus tremuloides Michaux) produced at 30Pa and 56 Pa CO₂ and two levels of soil nitrogen (N) avalibility. Decomposition was quantified as microbially respired CO₂ and dissolved organic carbon (DOC) in soil solution, and concentrations of nonstructural carbohydrates, N, carbon (C), and condensed tannins were monitored throughout the incubation. Growth under elevated atmospheric CO₂ did not significantly affect initial litter concentration of TNC, N, or condensed tannins. Rates of decomposition, measured as both microbially respired CO₂ and DOC did not differ between litter produced under ambient and elevated CO₂. Total C lost from the samples was 38mg g^-1 litter as DOC, suggesting short-term pulses of dissolved C in soil solution are important components of the terestrial C cycle. We conclude that litter chemistry and decomposition in trembling aspen are minimally affected by grwoth under higher concentrations of CO₂.