Long-term effects of elevated carbon dioxide concentration on sour orange tree specific gravity and anatomy

Exposure to elevated levels of atmospheric CO₂ for a period of 17 years resulted in small but statistically significant decreases in wood basic specific gravity and number of rays per millimeter. Other anatomical characteristics (percentages of tissues, number of vessels per square millimeter, vessel diameters, and fiber wall thickness) were unaffected by treatment. Differences due to distance from pith were important, but cardinal direction (north, south, east, west) was not.