Plant and Soil 165: 115-127, 1994.
Effects of elevated CO2 and nitrogen fertilization pretreatments on decomposition on
tallgrass prairie leaf litter
Paul R. Kemp1, Deborah G. Waldecker 2, Clenton E. Owensby3, James F. Reynold1 and Ross A. Virginia4
1 Department of Botany, The Phytotron, Duke University, Durham, NC 27706, USA,
22 Department of Biology, San Diego State University, San Diego, CA 92182, USA,
3 Department of Agronomy, Kansas State University, Manhattan, KS 66506, USA and
44 Environmental Studies Program, Dartmouth College, Hanover NH 03755, USA
Key words: Andropogon gerardii, carbon chemistry, carbon dioxide, litter quality,
Poa pratensis, Sorghastrum nutans
Abstract
Standing dead and green foliage litter was collected in early November 1990 from Andropogon gerardii (C4), Sorghastrum nutans (C4), and Poa pratensis (C3) plants that were grown in
large open-top chambers under ambient or twice ambient CO2 and with or without nitrogen
fertilization (45 kg N ha-1 ). The litter was placed in fine mesh bags on the soil surface
of pristine prairie adjacent to the growth treatment plots and allowed to decay under
natural conditons. Litter bags were retrieved at fixed intervals and litter was analyzed
for mass loss, carbon chemistry, and total Kjeldahl nitrogen and phosphorus. The results
indicate that growth treatments had a relatively minor effect on the initial chemical
composition of the litter and its subsequent rate of decay or chemical composition.
This suggests that a large indirect effect Of CO2 on surface litter decomposition in
the tallgrass prairie would not occur by way of changes in chemistry of leaf litter.
However, there was a large difference in characteristics of leaf litter decomposition
among the species. Poa leaf litter had a different initial chemistry and decayed more
rapidly than C4 grasses. We conclude that an indirect effect Of CO2 on decomposition
and nutrient cycling could occur if CO2 induces changes in the relaive aboveground
biomass of the prairie species.
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