Researching the Effects of
Rising Atmospheric CO2 on Plant Communities

It has been well established that rising CO2 will stimulate plant growth. Indeed, climate change associated with rising atmospheric CO2 has already altered ecosystem carbon balance through rising temperature, increased growing season, and increased atmospheric water content. Studies in native ecosystems have shown that while grasslands show a relative small stimulation of shoot growth, woody plants respond vigorously to elevated CO2.

How much additional carbon will be added to terrestrial ecosystems as a result of the CO2 fertilization effect will depend on feedbacks of environmental factors on the major resources of nutrients, water and light. Additionally the interaction between plant physiological responses to elevated CO2 and environmental factors in native species and in ecosystem processes is not well understood.

Rising atmospheric CO2 has the potential to stimulate carbon accumulation in ecosystems through direct effects on photosynthesis and growth of plants. But because growth of native species is often limited by the supply of water and nutrients, particularly nitrogen, it is not clear whether, in the long-term of years to decades, CO2 stimulation of plant growth would add significant amounts of anthropogenic carbon as soil carbon to ecosystems. Moreover, the possibility that additional carbon would be sequestered in long-term, carbon pools in the soil has not been determined in native ecosystems.

We are attempting to determine the impact of elevated atmospheric CO2 on the mechanisms that regulate carbon dioxide assimilation, biomass allocation, organic decomposition, ecosystem and plant respiration, nutrient mineralization, and carbon storage and export regulate ecosystem carbon balance.