Germination of Forest Trees 3 5 



of it that had never been attacked. Some of the questions that 

 are immediately called to mind by a mere statement of the prob- 

 lem are: Does light affect germination in any way? Does light 

 affect the germination of tolerant and intolerant species differ- 

 ently ? How does soil moisture content affect germination ? Do 

 drought-enduring species and moisture-loving species behave 

 alike in this respect? What is the effect of soil texture upon 

 germination? Has the amount of air or oxygen in the soil any 

 significance in germination? Since soil texture affects mainly 

 the moisture content of the soil, does soil texture affect drought- 

 enduring species in the same way as moisture-loving species ? 



The data collected upon the effect of habitat factors on germina- 

 tion will be presented in four parts. The effect of light, soil 

 moisture, and soil texture will be taken up in the order named 

 and following this there will be given a resume of the relative 

 effect of all habitat factors. The three most important points 

 to be noted in germination, are the number of days it took until 

 germination began, the total number of days in the germination 

 period, and the final germination per cent. The rate of germina- 

 tion is shown by curves for certain representative species. The 

 length of the germination period was taken as the total number 

 of days during which any seeds germinated. Records were kept 

 long after germination ceased, so that the germination period was 

 ended at the time the last seed germinated. To give data as to 

 the period of greatest activity involves certain arbitrary standards 

 and this method, though tried in compiling the present data, was 

 abandoned. The effect of light, soil moisture, and soil texture 

 upon the periods of greatest activity is best shown by the curves 

 offered for certain representative species. 



The original data was taken by two-day periods. Every other 

 day the number of seeds that germinated were counted and re- 

 corded. In most cases these were immediately pulled up ; but 

 where growth measurements were to be taken later the seedlings 

 were allowed to grow. 



The first three tables show the effect of light upon the germina- 

 tion of eastern species, Rocky Mountain species, and Pacific coast 

 species respectively. Three sets of figures are given under each 



