DB1018

A Comprehensive Database of Woody Vegetation Responses to Elevated Atmospheric CO₂

Peter S. Curtis, The Ohio State University

Prepared by: Antoinette L. Brenkert, CDIAC

DB1018 (1997)

This multiparameter database was compiled by Peter Curtis to perform a statistically rigorous synthesis of research results on the response by woody plants to increased atmospheric CO₂ levels. Eighty-four independent CO₂-enrichment studies, covering 65 species and 35 response parameters, met the necessary criteria for inclusion in the database, reporting mean response, sample size, and variance of the response (either as standard deviation or standard error). The data were retrieved from published literature and, in a few instances, from unpublished reports. Meta-analytical methods have been applied to part of this database.

This database allows the exploration of the effects of environmental factors (e.g., nutrient levels, light intensity, temperature), stress treatments (e.g., drought, heat, ozone, ultraviolet-B radiation), and experimental conditions (e.g., duration of CO₂ exposure, pot size, type of CO₂ exposure facility) on plant responses to elevated CO₂ levels.

Physiological "acclimation" or "downward regulation" of photosynthetic rates, stomatal conductance, dark respiration, and water-use efficiency of plants exposed to elevated CO₂ levels can be analyzed, keeping the following definitions in mind. "Acclimation" is, in general, defined as "diminishing enhancement of photosynthesis by elevated CO₂ with time." "Downward regulation" is defined as "the initial stimulation of enhanced photosynthesis and growth by atmospheric enrichment eroding with time." The phenomenon is also called "downward acclimation" (i.e., "following prolonged exposure to high CO₂, photosynthetic capacity measured at either elevated or ambient CO₂ partial pressure falls to below that of plants exposed only to ambient CO₂"). Only the longest lasting exposure experiment results on photosynthetic rates, stomatal conductance, dark respiration, and water use efficiency are included; however, multiple measurements over time from the same plant, are not included. Only responses of plant growth at ambient levels of CO₂ and plants grown at elevated CO₂ levels, measured at elevated CO₂-level concentrations, are included for evaluate of acclimation. Duration of experimental exposures are always reported.

This database is meant to be expanded in the future with the plant responses of nonwoody vegetation to elevated atmospheric CO₂.

kng 05/98