Response of Trees to CO₂ Increase

Abstract

Among the principal abiotic requirements for plant growth, namely, light, water, nutrients and carbon dioxide, CO₂ is an anthropogenic gas associated with potential global warming. Any change in the availability of the above abiotic elements will impact not only plants, but the entire living systems. The current annual rate of increase in CO₂ (~0.5 %) is expected to continue with concentrations exceeding 600 ppm by the end of this century from the current 380 ppm (Houghton et al. 2001). Such an increase in the CO₂ levels will certainly affect the globally important process of photosynthesis, which sustains the life on this planet. Hence this has been the subject of intensive research during the past half a century. Since this book is going to deal with only the impact of climate change on fruit trees, the reader is referred to a number of general publications on this subject (e.g. Koch and Mooney 1996; Murray 1997; Luo and Mooney 1999; Reddy and Hodges 2000; Karnosky et al. 2001; Ziska and Bunce 2006; Kallarackal and Roby 2012). It is important to remember that as the methodology for artificial CO₂ enrichment experiments is improving around the groups concentrating on this research, our understanding of the response of plants to elevated CO₂ has been changing. All methods used during the past, namely, chamber methods and Free-Air-Carbon dioxide-Enrichment (FACE) have both positive and negative attributes and hence data obtained through any method should be treated with caution. Moreover, there is much interaction of CO₂ with other biotic and abiotic factors, which is usually ignored in many studies.