![Sample our Environment & Sustainability journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5935/TOC-Subject-Sample-2021-Environment-Sustainability.jpg"})
Abstract
The CO 2 fertilization hypothesis stipulates that rising atmospheric CO 2 has a positive effect on tree growth due to increasing availability of carbon. The objective of this paper is to compare the recent literature related to both field CO 2 -enriched experiments with trees and empirical dendrochronological studies detecting CO 2 fertilization effects in tree-rings. This will allow evaluation of tree growth responses to atmospheric CO 2 enrichment by combining evidence from both ecophysiology and tree-ring research. Based on considerable experimental evidence of direct CO 2 fertilization effect (increased photosynthesis, water use efficiency, and above- and belowground biomass), and predications from the interactions of enriched CO 2 with temperature, nitrogen and drought, we propose that warm, moderately drought-stressed ecosystems with an ample nitrogen supply might be the most CO 2 responsive ecosystems. Empirical tree-ring studies took the following three viewpoints on detecting CO 2 fertilization effect in tree-rings: 1) finding evidence of CO 2 fertilization effect in tree-rings, 2) attributing growth enhancement to favorable climate rather than atmospheric CO 2 enrichment, and 3) considering that tree growth enhancement might be caused by synergistic effects of several factors such as favorable climate change, CO 2 fertilization, and anthropogenic atmospheric deposition (e.g., nitrogen). At temperature-limiting sites such as high elevations, nonfindings of CO 2 fertilization evidence could be ascribed to the following possibilities: 1) cold temperatures, a short season of cambial division, and nitrogen deficiency that preclude a direct CO 2 response, 2) old trees past half of their maximum life expectancy and consequently only a small increase in biomass increment due to CO 2 fertilization effect might be diminished, 3) the elimination of age/size-related trends by statistical detrending of tree-ring series that might remove some long-term CO 2 -related trends in tree-rings, and 4) carbon partitioning and growth within a plant that is species-specific. Our review supports the atmospheric CO 2 fertilization effect hypothesis, at least in trees growing in semi-arid or arid conditions because the drought-stressed trees could benefit from increased water use efficiency to enhance growth.
ACKNOWLEDGMENTS
We thank Dr. Feng Xiahong for providing , Blackwell Publishing for the granted permission to reproduce and , New Phytologist for the granted permission to reproduce . Venceslas Goudiaby for formatting the manuscript, and Dr. Young-In Park for his helpful comments on the early draft. Particular thanks are due to Dr. Paolo Cherubini (WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Switzerland), Dr. Martin Lechowicz (Mcgill University, Canada), Dr. Xianzhong Wang (Indiana University-Purdue University Indianapolis, USA), and editor Dr. Dennis J. Gray for their critical and valuable comments and suggestions on the early manuscript. This work was funded by the Canada Chair in Forest Ecology and Management hold by Dr. Yves Bergeron at the University of Quebec at Abitibi-Témiscamingue, Quebec, Canada.