REPRODUCTION OF WESTERN YELLOW PIXE. 27 



The foresummer of 1915 did not bring the usual prolonged drought, 



but the summer rains were light. Records for sample plots 3a and 

 3b (Table 3) show a heavy loss of 1914 seedlings during the fall of 

 1915. and again in the spring of 1910, when no rain fell from April 

 1 to July 7. save for a shower of 0.35 inch in May. Nevertheless, the 

 seedlings which originated in 1914 were sufficient in number to make 

 a real start toward restocking sample plots 3a and 3b. This survival 

 is attributed to the absence of severe droughts in the fall of 1914 

 and the spring of 1915. Had the summer rains of 1915 been up to 

 the usual standard, and if the April-June drought of 1916 had been 

 less severe, it is reasonable to believe that a much higher survival 

 would have resulted. As it was. excellent reproduction took place on 

 local areas in the vicinity of Fort Valley and on extensive areas in 

 other localities. The poorer showing on sample plots 3a and 3b. as 

 compared with certain other areas, is attributed partly to the heavy 

 soil on these plots and partly to the fact that the seedlings were 

 forced to compete with a dense growth of grass. Results in this 

 region, as a whole, form the basis for the conclusion that if a good 

 seed crop is followed by one year of abundant and properly distrib- 

 uted rainfall, good reproduction will take place on the more favor- 

 able sites, but that on the more adverse sites two or more consecutive 

 years of favorable moisture conditions are required. 



Xo seedlings originated in 1915. because of a total absence of seed. 

 The rainfall graph from August 1 to October 31 points clearly to the 

 fate which would have awaited any seed which might have been 

 borne in 191-1. 



The light seed crop of 1915 gave rise to appreciable numbers of 

 seedlings. This result is attributed to the favorable summer and 

 fall of 1916 and the absence of a severe drought during May and June 

 of the following year. Beginning in the latter part of September, 

 1917. and extending to the middle of January. 1918. we had the long- 

 est continuous rainless period of 12 years. Notwithstanding heavy 

 losses of both first and second year seedlings, a few survived. Seed- 

 lings over 2 years old resisted the drought surprisingly well. Xo 

 doubt the mortality in all age classes would have been heavier but for 

 the fact that the soil did not become very dry until after the close 

 of the growing season. 



In the fall of 1918 a tremendous seed crop occurred generally over 

 the entire Colorado Plateau. It was particularly heavy in the 

 vicinity of the Fort Valley Experiment Station. Rain was abundant 

 and well distributed during practically the entire growing season 

 of 1919. For the first time on record germination took place in 

 May and early June. Most of these seedlings survived a light 

 drought in the latter part of June, and they were supplemented by 

 myriads during the summer rainy period, which began promptly 



