Georg Thieme Verlag Stuttgart KG · New York
Effect of Seed Size on Seedling Growth Response to Elevated CO2 in Picea abies and Picea rubens
Received: February 10, 2007
Accepted: March 19, 2007
12 June 2007 (eFirst)
Several previous studies have observed that species and individuals with large seeds respond more positively to elevated CO2 than those with small seeds. We explored the reasons for this pattern by examining the relationship between seed size and CO2 response in Picea abies and P. rubens using growth analysis. The large seeded species (P. abies) responded more positively to elevated CO2 than the small seeded species (P. rubens). At the intraspecific level, P. abies individuals from large seeds responded more positively to elevated CO2 than individuals from small seeds, however, there was no significant intraspecific variation in CO2 response in P. rubens. The greater CO2 response of plants from large seeds was not simply the result of a larger starting capital compounded at the same rate as in plants from small seeds. Elevated CO2 increased relative growth rate to a greater extent in individuals from large seeds. This effect appears to be related to differences in time of establishment, source to sink ratio and nutrient availability with seed size. These results are significant not only in understanding the potential effect of rising atmospheric CO2 concentrations on plant populations, but also in understanding the factors affecting plant success at current atmospheric CO2 levels due to the elevation of CO2 within the litter layer that occurs at many germination sites.
Functional group - seed size - elevated CO2 - growth analysis - source : sink ratio - nitrogen availability.