from summaries of previous tests was used in a series of direct seeding trials in 

 northern Idaho and western Montana during the period 1937 to 1940 (Schopmeyer and 

 Helmers 1947) . Results show that with effective protection from animals ponderosa 

 pine can he seed-spotted successfully on favorable sites that have been recently and 

 severely burned (Helmers 1946) . 



The two major difficulties in direct seeding are animals and the harsh environ- 

 mental forces (Wagg and Hermann 1962) . Hand-sown seed and the seedlings germinating 

 from them suffer from the same agents of first-year mortality as naturally sown seed 

 and seedlings. Planting, on the other hand, partially overcomes these destructive 

 agencies . 



Ground preparation. — Any of the methods described in the section on site prepara- 

 tion can successfully reduce competition, but for direct seeding a method that exposes 

 mineral soil should be chosen because pine seeds germinate best in that medium. Culti 

 vating or loosening the soil on the spots before sowing increased germination in one 

 test (Loewenstein and Pitkin 1966) and had no appreciable effect in another test 

 (Schopmeyer and Helmers 1947) in northern Idaho. 



Sowing rates. — In early seeding studies the tendency was to sow large numbers of 

 seeds to insure establishing some seedlings. For example, 20 to 25 seeds were sown 

 per spot, and this often resulted in spots with many seedlings in close competition. 

 Some foresters believed the excessive numbers of seedlings necessitated thinning to 

 prevent stagnation, loss of growth, or the development of poorly formed trees (Stein 

 1957; Wagar and Myers 1958) . One northern Idaho study showed that the number of seed- 

 lings per spot significantly affected both diameter and height growth of dominant 

 ponderosa pine trees for 17 years after spot seeding (Foiles 1961). Although a satis- 

 factory stand developed without thinning, sparsely stocked plots had a notable growth 

 advantage . 



In recent years, a trend toward reduced sowing rates reflects greater experience 

 with direct seeding and a preference for lower initial stocking in reproduction stands. 

 Most management guides now recommend 400 to 500 established seedlings per acre. Sowing 

 rates should be based on the ratio of the number of viable seeds sown to the number of 

 established seedlings at some predetermined age. Unfortunately, the seed-to-seedling 

 ratio is not easy to predict. It varies by sites and is affected by site preparation, 

 seed viability, weather in a particular year, seed protection measures, and other 

 factors. Tests of seeding on different sites are needed to develop seed-to-seedling 

 ratios for sowing guides and to help determine which sites can be seeded economically. 

 Until results are known, the germinative capacity of individual seed lots will help 

 determine sowing rates . 



Sowing season. — Fall sowing usually has been more successful than spring sowing 

 (Wahlenberg 1925; Schopmeyer and Helmers 1947). Fall-sown seed is stratified 

 naturally over winter and is ready to germinate early in the spring. Spring sowing 

 is often delayed because the planting sites are inaccessible until mountain roads 

 become passable. If seed can be sown early enough, however, spring sowing does have 

 an advantage over fall sowing; protection from rodents and birds is needed for a much 

 shorter time. 



Seed protection. --Various methods of protecting planted seeds from rodents and 

 birds have been tried (Wahlenberg 1925; Schopmeyer and Helmers 1947; Maki 4 ). In 

 experimental seedings, losses to rodents have been reduced effectively by placing wire 

 screen cones over seed spots, but the screening method is too expensive for general use 



^\ E. Maki. Artificial seeding of tree species in the Intermountain Region. 

 Intermt. For. $ Range Exp. Stn. , Moscow, Idaho. File rep., 45 p. 1938. 



1" 



