Carbon-based Secondary Compounds at Elevated CO<sub>2</sub>

From literature sources we compiled the data on carbon-based-secondary compounds CBSC (phenolics and terpenoids) and biomass of 17 plant species grown at different CO2 concentrations under low and high nutrient availabilities. With a low nutrient availability a possible inverse correlation was found between the biomass and CBSC changes. On the contrary, under a high nutrient availability, both the CBSC and biomass increased with elevated CO2. The wide variation in the CBSC production among species and compounds (larger responses in phenolics than in terpenoids) indicates that the allocation to CBSC may not completely be governed by changes in CO2 and nutrient availabilities per se. Yet the comparison shows that elevated CO2 generally loads the carbon into CBSC [their leaf concentration increased an overall average of 14 % at 700 umol(CO2) mol-r] which may improve our understanding of the carbon storage and cycling in ecosystems under the "global change" of climate.