New Ecosystem Carbon Exchange in Two Experimental Grassland Ecosystems

• Published in: Global change biology Vol. 10; no. 4; p. 498
• Main Authors: Verburg, Paul SJ, Arnone, John A, Obrist, Daniel, Schorran, David E, Evans, RDavid, Leroux-Swarthout, Debbie, Johnson, Dale W
• Format: Journal Article
• Language: English
• Published: 01.04.2004
• ISSN: 1354-1013

Results are presented from a 2-yr study in which net ecosystem exchange was measured directly in two experimental grassland ecosystems using the Desert Research Institute's Ecologically Controlled Enclosed Lysimeter Laboratories. Cheatgrass Bromus tectorum grassland ecosystems were constructed using soil originating from the Konza prairie, the isotopic composition of which is different from that of cheatgrass, which allowed the contribution of plants to belowground C flows to be measured directly. Results show that it took 62 d from seeding for the C balance to become positive, and after harvest, the ecosystem C balance rapidly approached zero, indicating that the grass did not contribute substantially to overall ecosystem C sequestration. Net ecosystem production was larger for the fertilized then for the unfertilized period due to a longer period during which maximum net ecosystem exchange was attained. Soil organic-matter decomposition was stimulated by the presence of plants, but fertilization lowered soil organic-matter decomposition, especially during the first three months after planting. During the unfertilized growing period, C leaching losses were 16% of the losses through soil respiration.