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Volume 2 Number 3:  1 February 1999

Editorial
State of Union Speech Ill Reflects State of Nature: Knowing that government policy initiatives are not always based on sound science, we listened attentively to President Clinton's 1999 State of the Union speech, hoping for the best, but expecting the worst.  And as fate -- or Al Gore -- would have it, the President's address more than exceeded our expectations...

Journal Reviews
An Urban CO2 Dome: Carbon dioxide concentrations measured across various transects of a major metropolitan area reveal a region of enhanced CO2 concentration in the central portion of the city, where CO2 levels may be as much as 50% greater than surrounding rural values.

Temporal Variability of Urban CO2 Concentrations: Measurements of near-surface atmospheric carbon dioxide concentrations in the Phoenix metropolitan area revealed that elevated summertime concentrations within the city are of similar extent and magnitude as those of winter, suggesting that Phoenix's urban CO2 dome is largely independent of mean climatic conditions.

A 2000-Year History of Drought: Two thousand years of drought history were examined for the central United States, revealing that severe droughts of long-lasting duration are a regular feature of the climate of this region.

Room for Maneuvering: Assessing our current understanding of climate change, the author concludes that "a very important issue in the global warming debate remains unresolved."

Regional Climate Change: This News Focus item highlights the importance of regional land-use activities on regional climate, as well as the inability of current generation general circulation models to ascertain their influences on global climate.

Effects of Atmospheric CO2 on Plantago lanceolata: Plantago lanceolata seedlings grown for six weeks at 800 ppm CO2 displayed biomass increases that were much greater than those obtained from seedlings grown at 400 ppm CO2.  Elevated CO2 did not affect the amount of root exudation into the soil, but it did affect the amount of carbon transferred there by increasing root biomass.

Effects of Elevated CO2, Soil Nitrogen and Phosphorus on Growth and Fungal Colonization of Pine Trees: Ponderosa pine seedlings grown for twelve months at atmospheric CO2 concentrations of 525 and 700 ppm exhibited large increases in root, shoot, and total dry weights, relative to control plants grown at ambient CO2.  In addition, elevated CO2 dramatically increased the total number of ectomycorrhizal fungi associated with their roots.

Effects of CO2 on Fungi and Pine: Elevated CO2 significantly increased Scots pine seedling dry mass after four months, regardless of concomitant inoculation with various mycorrhizal fungi.  For inoculated plants, elevated CO2 accelerated hyphal growth, increased hyphal tips associated with roots, and led to the establishment of greater mycorrhizal networks throughout the growth media.

Effects of CO2 on Temperate Forest Regeneration: Two years of elevated CO2 exposure increased total plant biomass by 31% in regenerating temperate forest mesocosms composed of intact soil chunks removed from a New England study site.  It also led to increases in the percentage of ectomycorrhizal root tip colonization for every tree species within the mesocosms, implying that their abilities to acquire soil nutrients should increase as the CO2 content of the air continues to rise.

Effects of Fungi on Prairie Plants: Total plant dry weight significantly increased for perennial warm-season C4 grasses and perennial forbs inoculated with arbuscular mycorrhizal fungi, while perennial cool-season C3 grasses and annual forbs were basically insensitive to fungal symbiosis.