SEED SURVIVAL 



Large numbers of ponderosa pine seeds are usually destroyed on the ground prior 

 to spring germination. Seeds lost to rodents and other factors during the period 

 from dispersal to germination were determined at Bluesky (1948-1951, and 1953) and 

 at Dunn and Butler (1951, 1953, and 1954). 



Methods 



From 10 to 39 quarter-milacre duff samples were taken next to seed traps in May 

 of each year to study the number of unprotected seeds remaining over winter. The 

 differences between numbers of seed caught in the traps and the numbers found on these 

 duff plots represented the take by rodents and other seed destroying agents. 



Sunflower seeds coated with thallium sulphate were used to poison rodents and 

 protect the seed at the Dunn and Butler plots in early September 1951. Also, a 

 1000-foot buffer zone was treated on each side of the plots. 



Results 



Most of the pine and fir seed that reached the ground were destroyed prior to 

 germination. Squillace and Adams (1950) reported early in the study period that only 

 8 percent (5,800 seeds per acre) of the sound pine seed dispersed from the bumper 1948 

 seed crop at Bluesky remained undamaged at the time germination began in 1949. They 

 also found that 40 percent (1,200 seeds per acre) of the Douglas-fir seed that fell 

 from the poor crop in 1948 was available for germination the next spring. White-footed 

 mice and chipmunks were blamed for most of this loss based on population counts and 

 stomach analyses made on this area (Adams 1950). As this study continued, it was clear 

 that most of the seeds that reached the ground were destroyed by mice, chipmunks, or 

 other seed destroyers. The percent of seeds destroyed was always higher following 

 dispersal of poor or medium crops. 



During the 7-year period from 1949 to 1955, only 12 and 7 percent of the 

 cumulative number of pine and fir seeds, respectively, survived until spring. This 

 represented a total of only 14,000 pine and 20,200 Douglas-fir per acre. 



Seed eaters on the Dunn and Butler plots were not effectively controlled by a 

 single application of thallium sulphate-coated bait in early September of 1951. Initial 

 control was obtained, but invading mice took most of the seed by the following spring. 

 Although a few tree seeds probably were taken before poisoning, most were likely taken 

 after the fall rains leached the chemical off the bait. 



SEEDLING ESTABLISHMENT 



"Natural regeneration is almost always benefited by mineral soil seedbeds where 

 competing vegetation has been reduced by scarification, burning, or with chemicals. 

 Removal of competition increases the amount of water available for young seedlings. 

 This is particularly true for ponderosa pine that grows in the drier sites in western 

 Montana. 



10 



