CO2 and Trees: City Trees vs. Country Trees

Photosynthetic plants tend to react a certain way toward CO2--the more CO2, the faster they grow. It sounds like a feedback, to me. Looking at the country/city tree cousins:

“In the country, the trees were about up to my waist. In the city, they were almost over my head — it's really dramatic,” said Jillian W. Gregg, the study's lead author.

“No matter what soil I grew them in they always grew twice as large in New York City,” said Gregg, who said she was initially perplexed by the unexpected results. ____Source___via _M4GW__H/T_TomNelson

Another look at trees grown in different concentrations of CO2:

In May of 1999, four oak (Quercus ellipsoidalis) acorns were planted in each of 24 plots in each of six experimental FACE rings, three of which were maintained at an elevated atmospheric CO2 concentration of 550 ppm and three of which were maintained at the air's ambient CO2 concentration of 360 ppm. Half of the plots in each ring were weeded during the first three summers of the experiment; and in the summer of 2000, half of the plots received regular watering while the other half received no water during a 3.5-week period.

...In the words of the six Minnesota researchers, "the results showed that under hot and dry conditions, elevated CO2 can act like a nurse plant for tree seedlings growing in bare and unshaded areas, increasing seedling survival and growth, and thereby expanding the establishment window for trees encroaching into a grassland environment." In the specific situation investigated in their experiment, for example, they concluded that "increasing atmospheric levels of CO2 may be able to kick-start oak establishment into Cedar Creek's old fields."___CO2 Science_via_M4GW

CO2 is the gaseous fuel that feeds the ecosystem. Doubling atmospheric CO2 is less of a threat to the planet than halving atmospheric CO2 would be. The Biosphere is expandable, as long as there is enough sunlight and CO2. What is the optimal CO2 for earth? It depends. How much life do you want?