22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Ill 



From the qualitative standpoint, the trend ratios of table 9 give 

 a rather clear indication of the amount of agreement to be expected 

 between tree growth and rainfall where the two are as far apart as 

 any two of the rainfall stations. Quantitatively, trend coefficients 

 yield values to be expected in the same fashion. If variations in tree 

 growth mirror variations in rainfall to a high degree then the cor- 



Table 10. — Correlation behveen rainfall intervals at Chacon 



Trend coefficients and ratios of opposed trends 

 1909- 1941 

 Nov.-May vs. Jan.-Ma}' vs. 



Jan.-Aug 0.78 (0.26) Mar .-Apr 0.92 (0.22) 



Nov.-May vs. Jan.-May vs. 



Jan.-May 0.99 (0.06) Mar.-June 0.84 (0.22) 



Nov.-May vs. Jan.-May vs. 



Mar.-June 0.82 (0.29) May-Aug 0.14 (0.47) 



Jan.-Aug. vs. Jan.-May vs. 



Jan.-May 0.73 (0.28) May- June 0.18 (0.44) 



Nov.-May vs. Mar.- July vs. 



Mar.-July 0.77 (0.23) Mar.-Apr 0.67 (0.31 ) 



Nov.-May vs. Mar.-July vs. 



May-Aug 0.21 (0.48) Mar.-June 0.98 (0.12) 



Nov.-May vs. Mar.-July vs. 



May-June 0.17 (o.4S) May-Aug 0.85 (0.34) 



Nov.-May vs. Mar.-July vs. 



Mar.-Apr 0.90 (0.23) May-June 0.81 (0.22) 



Jan.-Aug. vs. Alay-Aug. vs. 



Mar.-June 0.87 (0.25) May-June 0.94 (0.25) 



Jan.-May vs. May-Aug. vs. 



Mar.-July 0.72 (0.22) Mar.-Apr —0.33 (0.66) 



Jan.-Aug. vs. May-Aug. vs. 



Mar.-July 0.97 (0.22) Mar.-June 0.66 (0.44) 



Jan.-Aug. vs. May-June vs. 



May-Aug 0.92 (0.25) Mar.-Apr —0.02 (0.47) 



Jan.-Aug. vs. May-June vs. 



May-June 0.69 (0.22) Mar.-June 0.87 (0.25) 



Jan.-Aug. vs. Mar.-Apr. vs. 



Mar.-Apr 0.56 (0.38) Mar.-June 0.90 (0.25) 



relation between Holman Pass trees and Chacon rainfall should closely 

 approach or possibly equal the average values set out in table 9. 

 Should this prove to be true, the conclusion is no doubt justified that 

 trees growing in a zone well above critical moisture conditions rather 

 faithfully record rainfall variations at the site from year to year, 

 barring the impact of an "accidental" factor in concentrated form in 

 any one year. 



Table 10 sets forth correlations between various month-intervals in 



