Figure 1. The relationship between tree growth and cool-season precipitation. The blue line shows the tree-ring growth index for El Malpais National Monument, New Mexico and the red line depicts precipitation recorded by rain gauges in New Mexico Climate Division 4. Notice that while the tree-rings do a good job of matching dry winters, they do not quite match the wet years. Above a certain threshold, precipitation is no longer limiting to tree growth. Also note the very dry conditions during the 1950s and the post-1976 wet period.
Source: Tree-ring chronology developed by Dr. Henri Grissino-Mayer. Chronology data available from the International Tree-Ring Data Bank (http://www.ngdc.noaa.gov/paleo/ftp-treering.html).
