Bibliography on CO₂ Effects on Vegetation and Ecosystems: 1990-1999 Literature (ORNL/CDIAC-129)

How the bibliography was developed

All citations for this bibliography were downloaded from the Science Citation Index of the Institute for Scientific Information. The first search term used was CO₂ and elev*. The downloaded citations were manually screened for relevance to the bibliography and approximately 60% were retained. This first search term accounted for 76% of the citations in the final bibliography. The second search term, CO₂ and enrich*, identified an additional 20% of citations relative to the use of the first search term alone and accounted for another 16% of the citations in the bibliography; 30% of the citations downloaded by using the second search term were incorporated into the bibliography. The third search term, CO₂ and enhanc*, identified an additional 5% of citations relative to the first and second search terms and accounted for only 4% of the citations in the bibliography; 15% of the citations downloaded by using the third search term were incorporated into the bibliography. Finally, the fourth search term, CO₂ and global change, also identified an additional 5% of citations relative to the first, second, and third search terms and accounted for 4% of the citations in the bibliography; 80% of the citations downloaded by using the fourth search term were incorporated into the bibliography. In all, approximately 20,000 citations were downloaded, of which about 2700 were retained in the bibliography.

Studies were retained for the bibliography based on the information provided in the title, keywords provided by the authors, and information in the abstract, if provided. If the authors included "elevated CO₂" or some variant thereof in any of these fields, and the paper referred to plants, related organisms, or ecosystems, then it was always included. Papers that referred to CO₂ treatments only in the abstract may have been inadvertently excluded during the sorting procedure. Studies of global change that did not include a CO₂ component were not included.

The papers retained for the bibliography included the following categories:

1. Direct effects of CO₂ on plant species and related organisms, including algae, aquatic vegetation, and lichens. This category includes some low-CO₂ studies. Studies that explicitly examined CO₂ compensation point were also included. Studies of global change that did not include a CO₂ component were excluded.
2. Effects of CO₂ on plant-soil interactions, including effects on mycorrhizae and other soil biota, and including decomposition studies.
3. Ecosystem-level studies, i.e., those examining whole-system responses to CO₂, particularly carbon and nutrient fluxes.
4. Studies examining trophic interactions other than soil-microbial studies. These were studies that explicitly examined effects of elevated CO₂ on plant-animal interactions in systems in which all trophic levels were exposed to elevated CO₂, and included herbivory and production of secondary compounds. Studies of insects alone were excluded.
5. Mathematical models that explicitly dealt with an elevated CO₂ effect on terrestrial ecosystems. Models that did not include a CO₂ component were excluded, as were those that were focused on oceanic or exclusively benthic or pelagic systems. General circulation and related climate-only models were excluded.
6. Review papers dealing with global change and explicitly including elevated CO₂ effects were included.
7. Methods papers dealing explicitly with techniques appropriate to the kinds of studies included in this bibliography were included.
8. Effects of elevated CO₂ on intact post-harvest vegetation, particularly fleshy fruits but including grains. These papers examined effects on spoilage and plant-insect interactions. Studies examining effects of CO₂ on processed foods were excluded. The putative relevance is simply a broad approach to effects of CO₂ on vegetation and its components parts.
9. Paleo studies that explicitly directed their results or discussion to effects of elevated CO₂ and global change in a current and future context.

All or nearly all citations in this database are published in journals. The search procedure did not identify books or chapters in books that might be appropriate to include in this bibliography.

The keywords retained in the bibliography are those provided by the Institute for Scientific Information. The editors of this bibliography have not changed the keywords downloaded from the Science Citation Index, other than to correct a few obvious typographical errors and delete a few obviously invalid keywords. Thus, the user should be careful in using these keywords, such as by checking for all possible variants of a keyword (e.g., singular versus plural, specific versus general, and variant spellings).

Acknowledgements

The editors and CDIAC would like to acknowledge the following individuals for their assistance with this project: Mr. James Testa at the Institute for Scientific Information, for granting permission to make this information publicly available; and N. Ceja, M. Howell, T. Johnson, P. Moran-Palma, and G. Zwerling at The Ohio State University.

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