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Real-World Increases in Air's CO2 Concentration Help Real-World Trees Better Bounce Back from Real-World Droughts
Knapp, P.A., Soule, P.T. and Grissino-Mayer, H.D.  2001.  Post-drought growth responses of western juniper (Juniperus occidentalis var. occidentalis) in central Oregon.  Geophysical Research Letters 28: 2657-2660.

What was done
The authors developed tree-ring index chronologies from several hundred cores obtained from western juniper stands in four Research Natural Areas (RNAs) and one proposed RNA in central Oregon.  They then picked the first third of the record (1896-1930, when the air's CO2 concentration rose from 295 to 306 ppm) and the last third of the record (1964-1998, when the air's CO2 concentration rose from 320-367 ppm) to compare the trees' ability to recover from drought in the two periods of different atmospheric CO2 concentration.  They also determined, as important ancillary information, that there was no significant trend in winter/spring precipitation for the 1896-1998 period, nor for either the early or late period.

What was learned
The authors found that juniper trees recovered better from the effects of drought in the 1994-1998 period, when the average CO2 concentration of the air was 343 ppm, than in the 1896-1930 period, when the average CO2 concentration of the air was 300 ppm, noting that "greater recovery following drought in the late period is consistent with the expected ameliorating influences of atmospheric CO2 under stressful conditions," which they attributed to a CO2-induced increase in tree water use efficiency in the late period and for which they cited much corroborative information.

What it means
Stating that their results "suggest the ability of western juniper to recover from drought during the 20th century has increased," the authors indicate that this phenomenon may be the driving force behind the observation that "western juniper has continued to expand its range during the 20th century."  We agree, concluding that the ongoing rise in the air's CO2 content portends more of the same good news for the 21st century, as the great CO2-induced "greening of the earth" continues.

As an aside, it is interesting to note that in spite of the tremendous biological devastation climate alarmists claim should accompany what they have already described as the most dramatic warming of the past millennium, the real-world of nature -- where not adversely influenced by any direct deleterious activities of man -- is doing just the opposite: it is thriving.