Paleo Slide Set: Tree Rings: Ancient Chronicles of Environmental Change
Baldcypress (Taxodium distichum) in Bayou DeView, Arkansas.

Information about a particular climate variable can be maximized through 
careful site selection. For example, if one is interested in how rainfall 
has varied over time, a steep, rocky, dry, south-facing slope in an arid 
environment may be selected to find trees under maximum water stress. 
In such cases, ring width is a strong proxy for precipitation. 
In the previous slide, the foxtail pines in the cold environment 
near upper treeline are sensitive to summer temperatures and growing 
season length. They will likely reflect these variables in their ring-width 
patterns. In this slide, the baldcypress growing in a swamp is, surprisingly, 
a good recorder of spring rainfall in the southeastern United States. 
High rainfall is related to high dissolved-oxygen levels, which promote 
baldcypress growth. The baldcypress root system, responsible for uptake 
of water and nutrients, also appears to be very sensitive to water level.

Photo Credits:
Dave Stahle
Department of Geography, University of Arkansas, Fayetteville, AR