Effects of elevated atmospheric CO₂ on plant root system: A review

Living in an environment with increasing carbon dioxide concentration for long, the structure and function of plant will be affected, reflecting not only in the aboveground part, but also in the underground part, especially in the fine roots length, diameter, biomass, turnover, and spatial distribution. The changes of plant root system's structure and function will in return affect the carbon dynamics in the matter cycling of plant aboveground part and related ecosystem as well as the dynamics of soil carbon pool. At present, the researches on the effects of elevated CO₂ on root system mainly include two aspects, i.e., the effects on root structure (diameter, branch, length, and number), and those on root physiology (turnover, biomass, and carbon allocation). However, there still exist shortages in this field. For example, the regulation mechanisms of root system under elevated CO₂ condition and the dynamic changes of matter cycling and energy flow induced by the elevated CO₂ are less understood, and less convincing evidences are obtained to illustrate whether elevated CO₂ promotes the turnover of root. For the future, the researches of root turnover and carbon allocation under elevated CO₂ condition, co-effects of elevated CO₂ and other environmental factors on root system, and comparisons of the effects of elevated CO₂ under different site conditions should be strengthened.