ScienceDaily (Aug. 4, 2009) — Pine trees grown for 12 years in air one-and-a-half times richer in carbon dioxide than today's levels produced twice as many seeds of at least as good a quality as those growing under normal conditions, a Duke University-led research team reported Aug. 3 at a national ecology conference.
http://www.sciencedaily.com/releases/2009/08/090803173246.htm