Methods: 1990-1999 Bibliography on CO2 Effects on Vegetation and Ecosystems
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:
- 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.
- Effects of CO2 on plant-soil interactions, including effects on mycorrhizae and other soil biota, and including decomposition studies.
- Ecosystem-level studies, i.e., those examining whole-system responses to CO2, particularly carbon and nutrient fluxes.
- 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.
- 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.
- Review papers dealing with global change and explicitly including elevated CO2 effects were included.
- Methods papers dealing explicitly with techniques appropriate to the kinds of studies included in this bibliography were included.
- 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.
- Paleo studies that explicitly directed their results or discussion to effects of elevated CO2 and global change in a current and future context.
All citation information necessary to identify and locate a publication, including keywords and abstracts (when available), was imported into a PapyrusTM bibliographic database. Citations are identified by accession number, and are not sorted or internally categorized in any way in the PapyrusTM database (although they are sorted by author and year in the WordPerfect and ASCII listings). Because the database is electronic, searchable, and customizable by individual investigators, the formatting codes for subscripts, superscripts, or italics in PapyrusTM are not used. Wherever possible, the editors corrected spelling, punctuation, capitalization, and space errors found in the citations downloaded from Science Citation Index.
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).
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.