Under elevated CO2 photosynthesis was 15-50% higher than in chamber controls depending on the weather conditions of the growing seasons. When measured at 360 ppm CO2 both elevated CO2 and elevated CO2 + O3 treatments decreased net photosynthesis, stomatal conductance and also transpiration, indicating downregulation of photosynthesis at elevated CO2

The need to assess the role of terrestrial ecosystems in the global C cycle and the potential change of this role as the atmospheric concentration of CO2 increases attracted considerable scientific attention over the recent decade. In order to assess ecosystem responses as a whole and to evaluate the potential role of forests and tree communities as a carbon sinks, the below-ground response to increasing levels of CO2 must be addressed

There is still limited amount of information about the long-term and interactive effects of increased CO2 and O3 levels on larger forest trees growing under natural or semi-natural conditions. Elevated CO2 and O3 might affect the quality and quantity of leaf litter produced and thus change litter decomposition rates and nutrient cycling in the forest ecosystems severely. In this long-term field experiment we studied the effects of realistically increased CO2 and O3 levels on fine root and mycorrhiza growth in ozone-tolerant and ozone-sensitive silver birch clones by root ingrowth core method. We measured rhizosphere soil CO2 efflux plus assessed the total fungal biomass of fine roots and soil by ergosterol analysis

This paper summarizes the data on growth response and N uptake in open-top chambers planted with ponderosa pine (Pinus ponderosa Laws.) treated with both N (0, 10, and 20 g N msub-2 yrsub-1 as ammonium sulfate ) and CO2. Both N and elevated CO2 caused increased growth. The effects of N on growth response to elevated CO2 were assessed in various ways and various interpretations could be drawn depending on which metric was used, including a negative effect of N on growth response to CO2. These calculations suggest that expressing growth as percentages can be misleading, especially when done on a grams per tree basis

Atmospheric carbon dioxide (CO2) and ozone (O3) are increasing by 1-2% per year and are expected to double by the year 2100 compared to the end of the last millennium. Carbon dioxide at twice the current atmospheric concentrations has the potential to increase the productivity of forest trees while increasing ozone is expected to cause significant reductions in growth. The present study was undertaken to investigate the effects of CO2 and O3, singly or in combination, on growth and allocation of two European silver birch (Betula pendula Roth) clones under field conditions to verify the future predicitons in regard to silver birch. Our data show that growth of clone 80 was benefitted by ambient CO2 singly and in combination with ambient O3. Clone 4 was more responsive to ambient O3 than clone 80 which is opposite to results from previous pot experiments with these clones