Festuoa scahrella is the dominant vegetative species in the large openings and the 

 intermittent clearings within the stand. This species is also the major component of 

 the understory vegetation beneath the pine as long as the trees do not form a continuous 

 canopy. In heavily canopied areas, Catamagrostis ruhesoens is dominant. 



Livestock grazing has not been a significant factor since the early 1950' s and the 

 impact of deer and elk has been minimal. Some of the largest pine trees were selectively 

 logged in the early 1950 's, but their removal did not influence this study. 



METHODS 



The field plots were established in the summer of 1974 and involved two major 

 treatment groups. The first group of plots was situated within a ponderosa pine stand 

 and contained six treatments. The second group was located in large openings near, but 

 not under, the direct influence of the pine stand and had three treatments. Each treat- 

 ment had three replications giving 27 total plots. Each plot was a square, 13 feet 

 (4 m) on a side. The entire plot received a specific treatment and was fenced with 

 1/4-inch hardware cloth extending 30 inches (75 cm) above and 6 inches (15 cm) below 

 the ground. A 12-inch (30-cra) strip of heavy-duty aluminum foil was secured along the 

 top of the fence to discourage rodents from climbing into the plots. 



A 10- by 10-foot square (3- by 3-m) was centered and permanently marked within each 

 fenced plot. Each square was planted in November 1974 with 400 unstratified ponderosa 

 pine seeds collected on site a month earlier from dominant or codominant trees. After 

 the seeds were thoroughly mixed and their germinative capacity found to be about 84 per- 

 cent, they were planted in 20 rows and 20 columns spaced 6 inches (15 cm) apart. The 

 seeds were pushed slightly into the ground, but not buried, to prevent rolling or blow- 

 ing out of place. In plots with organic layers and vegetation left, the seeds were 

 placed next to mineral soil because this is where the majority of naturally fallen seeds 

 were found. 



The nine treatments were distinguished by differences in overstory canopy and vary- 

 ing amounts and methods of litter, duff, and vegetation removal (table 1). Treatment 

 designations indicate site features which were emphasized. 



A weather station was set up in a small opening near the middle of the study site 

 and a continuous record of air temperature, relative humidity, and precipitation was 

 kept from May 14 until November 11, 1975. Snow depths were determined on all plots on 

 March 24, 1975. 



Soil moisture contents were measured gravimetrically from soil samples collected 

 five times during the growing season. Sampling depth varies with collection dates, 

 starting with 0-2.8 inches (7.1 cm) on June 4, 0-4.3 inches (10.9 cm) on June 24, and 

 0-6 inches (15 cm) on July 21, August 13, and September 3. The depths of the first 

 two collection dates were approximately equal to the lengths of the longest roots of 

 newly germinated seedlings. This was done to compare moisture contents within the seed- 

 ling root zone. 



3 



