You are here:
EFFECTS OF ELEVATED CO2 AND OTHER ENVIRONMENTAL STRESSES ON WESTERN CONIFER SEEDLINGS
Citation:
Olszyk, D M., D T. Tingey, M G. Johnson, P T. Rygiewicz, AND T G. Pfleeger. EFFECTS OF ELEVATED CO2 AND OTHER ENVIRONMENTAL STRESSES ON WESTERN CONIFER SEEDLINGS. Presented at Air Pollution Workshop, State College, PA, April 15-18, 2002.
Description:
The future productivity of forests will be affected by increased levels of atmospheric CO2 which will likely be associated with climate change and regional air pollutants such as O3. We have conducted two long-term experiments to determine the effects of elevated CO2 and other stresses on tree productivity and the cycling of N and C within trees, litter, and soil In the first experiment, Douglas-fir was treated with elevated CO2 and/or elevated temperature for four years. In the second experiment ponderosa pine was treated elevated CO2 and/or O3 for three years. Seedlings in both experiments were grown in mesocosms where climatic and edaphic factors could be controlled and/or monitored. Native Douglas-fir or ponderosa pine forest soils and litter which were naturally low in N were used. In both experiments, elevated CO2 increased leaf photosynthesis and associated water use efficiency, decreased leaf N concentrations, and altered leaf carbohydrate concentrations; but had no effect on overall plant growth or biomass allocation. There were few interactions between elevated CO2 and either elevated temperature or O3 on any plant parameter. Thus, even though both Douglas-fir and ponderosa pine seedlings took up more C with elevated CO2, seedling growth was not affected, at least in part because low soil N was a limiting factor. Furthermore, the lack of seedling response to elevated CO2 was not modified by the concurrent temperature increase or moderate O3 stress in these studies.