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Volume 2 Number 22:  15 November 1999

Editorial
"Noticed the Weather Lately?": "Noticed the Weather Lately?"  This innocuous question introduces a one-page "HOTEARTH" advertisement in the 25 October 1999 New Republic...

Journal Reviews
Grasslands as Sinks for Atmospheric CO2: In a model study that incorporates the known effects of atmospheric CO2 enrichment on the growth and decomposition rates of perennial ryegrass, the authors demonstrate that the net enhancement in carbon sequestration that is caused by these phenomena is more than sufficient to make up for the CO2 that is released to the atmosphere by the decomposition-enhancing effect of warming.  They thereby demonstrate that the oft-stated concept of CO2-induced global warming being self-amplified by enhanced CO2 emissions produced by rising temperatures is invalid.

CO2 Effects on Decomposition of Soybean and Sorghum Tissues: The decomposition of plant tissues grown in atmospheres of ambient and elevated atmospheric CO2 concentration was found to be independent of CO2 treatment, suggesting to the authors that more carbon would be stored in agricultural soils in an "elevated CO2 world."

CO2 Effects on Decomposition Rates of Native Plants: A study of the quality and decomposition rates of leaf litter produced under ambient and elevated CO2 conditions in two grassland ecosystems and a tropical rainforest suggests that these phenomena are not affected by the rising CO2 content of the atmosphere.

Carbon Sequestration by Perennial Ryegrass Exposed to Elevated CO2 and Temperature: In a study of perennial ryegrass grown in large containers at two different levels of soil nitrogen, soil water, atmospheric temperature and atmospheric CO2 concentration, it was found that soil carbon storage was significantly enhanced by the elevated CO2 concentration of the air, even in the face of elevated temperature, which is often claimed to have just the opposite effect on soil carbon storage.

CO2-Induced Changes in Leaf Carbon and Nitrogen Status of Alpine Plants: An experimental investigation of the effects of atmospheric CO2 enrichment on the chemical composition of green and senesced leaf litter in an alpine ecosystem shows that changes induced in some of the green foliage of the ecosystem's component species disappears by the time the leaves senesce.

Effects of Long-Term Elevated CO2 Exposure on a Noxious Weed: After 19 months of atmospheric CO2 enrichment, a noxious weedy species known as bracken, did not exhibit any increase in biomass production, regardless of soil fertility.  In fact, when simultaneously grown under low nutrient conditions, atmospheric CO2 enrichment actually decreased the average frond area of this fern, suggesting that this fast-growing species will not proliferate and out-compete slower-growing species for limiting resources as the CO2 content of the air continues to rise.

Genotypic Responses of a Perennial Grass to Elevated CO2 and Temperature: After one year of treatment exposure, neither atmospheric CO2 enrichment nor elevated air temperatures significantly affected biomass production in ten related populations of a perennial grass collected from various European locations.  In addition, because there were no significant interactions found between population climate of origin and response to elevated CO2, the rising CO2 content of the air will likely maintain the genotypic diversity that exists within this species.

Effects of Short-Term Atmospheric CO2 Enrichment on Melon: Short-term atmospheric CO2 enrichment of five hours per day increased net photosynthetic rates in melon plants, regardless of irrigation solution salinity.  In addition, elevated CO2 reduced the negative effects of salinity on shoot growth, leaf growth, and leaf chlorophyll content, and increased fruit yield at all salinity levels.

Effects of Elevated CO2 on Dry Mass Partitioning in Three Species: Short-term atmospheric CO2 enrichment of 50 days or less significantly increased total dry mass of three plant species growing in a hydroponic system.  Although elevated CO2 increased shoot to root ratios for all three species in this experiment, it had little impact on dry mass partitioning when plant size was taken into account.

Effects of Atmospheric CO2 Enrichment on Subtropical and Tropical Fruit Trees: This mini-review of the scientific literature demonstrates that the rising CO2 content of the air will stimulate photosynthetic carbon fixation in leaves of subtropical and tropical fruit trees.  In addition, such trees will likely exhibit greater fruit yields, as the atmospheric CO2 concentration continues to rise.