34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Ill 



factors were eliminated and if the trees were properly selected from 

 the region and from the proper zone. 



Further to test the general relationships, the March- July and Jan- 

 uary-August rainfall of Chacon, Las Vegas, Taos Canyon, and Black 

 Lake were combined for the period 1 909-1 941 and correlated with 

 group 7. The results follow. 



Raw Smootliefl 



percentages percentages 



March-July 0.95 0.96 



(0.19) (0.22) 



January-August 0.96 0.86 



(0.16) (0.31) 



Although these values are high no advantage results from the use 

 of the combined rainfall. The raw percentage values for group 7 

 (restricted) correlated with combined rainfall of March- July are 

 0.955 and (0,22), and of January-August rainfall 0.955 and (0.12). 

 An analysis of table 17 shows, further, that altitude in general 

 has some effect: the correlations are slightly higher for group 9, 

 which is closer to the average elevation of the rainfall stations. 



Table 18. — Correlation of tree groups afui Las Vegas rainfall 

 Trend coefficients and ratios of opposed trends 



March-July 



1893- igio- 



1941 1941 



G 4 0.78 0.93 



(0.33) (0.28) 



5 0.73 0.81 



(0.31) (0.27) 



9 0.59 0.64 



(0.47) (0.44) 



7 0.79 0.91 



(0.35) (0.31) 



Trees HPC 3, 5, 7, and 9 were correlated with the stations listed 

 in table 17. The results are similar to those for the groups in the 

 table except for somewhat lower values. 



Tree growth and Las Vegas rainfall. — With the exception of 

 Santa Fe, Las Vegas has the longest rainfall record of any station in 

 the general area but it is some 37 miles distant from Holman Pass 

 and 3,000 feet lower. Table 18 gives the trend coefficients and the 

 ratios of opposed trends between tree growth and Las Vegas rainfall 

 for the intervals and years noted. On the whole, the correlations 



