Last fall we had a huge fall of acorns. Now (end of summer another, light so far, fall of acorns that started about 4 weeks ago (middle of summer). I called Max to gloat that this confirmed my theory about a coming El Nino event this winter. Now NWS has jumped on my bandwagon http://www.cpc.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html (non peer reviewed) that Quercus agrifolia predicts future weather events more than a year in the future.
here is an abstract of a paper by Steinberg, Peter D. 2002
He thinks that from the studies he’s seen that there is probably no direct correlation between future (or even past) rainfall and acorn production. I believe that if it was correlated to future El Nino or future drought there might be a connection. And a convenient predictor 18+ months in advance of El Nino events. At least that’s what I’ve observed here over the last 3 El ninos in Topanga.
Also in a paper by W. Koenig et al; http://www.nbb.cornell.edu/wkoenig/K075TA_96.pdf the researchers were unable to reach a conclusion on a definitive correlation between rainfall and acorn production in subsequent years.
Of course acorn production is a more complicated mechanism than prior years precipitation and depends also on more than just future rainfall projections. It also depends on trailing indicators like insect predation, and possibly subtle temperature and humidity variations during spring pollination. Of course those variations could also be predictors of future high rainfall seasons.
Acorn crops usually fall in November, this year 2009 we are having a large fall now, Aug Sept.
But I haven’t seen at least posted on the web a link between acorn production and future El Nino events up to 18 months away.
Need to find acorn crop production chart.