RESEARCH SUMMARY 



Study plots were established to determine the effects of various enviroa- 

 mental factors on ponderosa pine seed germination and initial seedling estab- 

 lishment and growth. A series of soil surface treatments were performed on 

 plots in two locations: within or under the influence of overstory pine trees 

 and in openings away fromthe pine influence. Seed germination was significantly 

 greater in the opening plots. The overstory canopy and forest floor restricted 

 the amounts of precipitation, light, and heat reaching the soil and probably 

 decreased germination. Cutworms, birds, and small mammals caused the 

 greatest seedling mortality. The largest seedUngs occurred in the fire- 

 treated plots. This was attributed to an increased nutrient supply and reduc- 

 tion of competition. Open-grown seedlings were larger than those growing 

 under the overstory canopy. Amount of sunlight, degree of competition, and 

 susceptibility to injury because of location appeared to be the major factors 

 contributing to the seedling size differences. Because of abnormally high pre- 

 cipitation during the growing season, results may not be tj^ical of average 

 growing seasons. 



CONTENTS 



Page 



INTRODUCTION 



1 



LITERATURE REVIEW 



1 



STUDY, 



3 



METHODS 



3 



RESULTS AND DISCUSSION 



6 



Fires 



General Weather Conditions .... 



Soil Moisture Content 



Natural Seed Occurrence 



Canopy Cover 



Solar Radiation 



Maximum Soil Surface Temperatures 



Soil Nutrient Analysis 



Seed Germination 



Seed Mortality 



Initial Seedling Establishment . . . 

 Seed Productivity 



6 

 6 

 7 

 8 

 9 

 9 

 9 

 9 

 11 

 13 

 16 

 17 



SUMMARY AND CONCLUSIONS 



23 



PUBLICATIONS CITED 



25 



