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The natural world. Looking pretty for 3.5b years.

1 in a 1000 & Blue Oaks

Author: Hugh Bollinger/Monday, September 14, 2015/Categories: natural history, sustainability, environment

Years ago, I ran a research project in Colorado at timberline to answer a question---when did old forest fires occur. The study required the development of a time-line for a series of major fires across multiple locations, many before historical fire or other records ever existed. The study required core samples to be taken from surviving trees using a steel borer, one of the prime tools of  dendrochronology . The rings from the core samples were tediously counted to confirm the length time the trees had re-grown since being damaged. thus determining a date for the timberline fire.

Trees add a growth ring each year. They are almost like pages from a book since the width of the ring responds to the tree's environment that year. If it has been a wet year, growth rings are wide; is it has been dry they are narrow, and it is very cold during the growing season there may be barely any ring at all. The dating of wood samples using dendrochronology is a powerful tool in ma
ny fields: archaeologists use cores to date ancient building timbers; ecologists use them to determine years that are wet or dry, hot or cold, and climate researchers use them to construct paleo-climates over century's-long time frames.

A report just released by  Nature climate change  tells a disturbing story about the current drought now hitting California---by using tree-rings from an endemic oak tree, the California Blue Oak ( Quercus douglasii ).

    
      California Blue Oak (Quercus douglasii) and its Coastal and Sierra Occurrence (credit: Wikicommons)

Combining tree-rings from earlier studies, the researchers reconstructed annual spring snowpacks in the Sierra Nevada mountains back to the year 1500. Valerie Trouet, article author and a tree-ring expert at the Laboratory of Tree Ring Research ( LTRR ) said the blue-oak trees rings hold particularly good records because “they are super-sensitive to winter precipitation”.

     
       
Sierra Nevada Snowpack and Tree-ring Comparison (credit: Laboratory of Tree-ring Research )

According to the article, by comparing tree-ring data with actual snowpack measurements over a contemporary 50 year time span shows:

"The historical data suggest that this year's low snowpack reading was an extreme event, likely unmatched in the past 500 years."  

and:

"This year’s snowpack is “strongly exceptional” exceeding the 95 percent confidence interval for 1,000-year return period. In other words, over 1,000 years, there is only a 5 percent chance of the snowpack being this low." 

The question remains as to what California will look like well before another 1000 years passes if a drought of this intensity continues like the past few years.

WHB








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