Regeneration Development 

 and Protection 



When is a seedling established? This question is difficult to answer. From the 

 time forest tree seed reaches the ground, either in the nursery or in the forest, until 

 the tree is harvested, natural forces work against its survival. Disease, insects, 

 birds, mammals, cold, heat, snow, hail, shade, too much water, too little water, wind, 

 and fire, directly or indirectly, can kill trees of different ages. The first few 

 years of a tree's life are probably the most critical. Until the young tree has had 

 several years to develop its crown and root system, its chance for survival is pre- 

 carious. A seedling is never established in the strict sense of the word, but we 

 can decide on a time when, for practical purposes, a seedling can be considered so. 



The loss of seedlings in the first 3 years after germination or after planting 

 probably represents a greater rate of loss in stems per acre than at any time in the 

 life of a ponderosa pine stand, except for episodes of fire and epidemics (Meyer 1961; 

 Korstian and Baker 1925; Pearson 1950; Tackle and Roy 1953; Foiles and Curtis 1965a). 

 The most important causes of mortality in these first 3 years are drought, insolation, 

 animals, and damping-off and other fungal diseases (Curtis and Coonrod 1961; Foiles 

 and Curtis 1965a) . After 3 years the seedlings are stronger and less susceptible to 

 some of these agents. Then others such as higher mammals, insects, diseases of roots 

 and foliage, competing plants, and weather become more prominent (Meyer 1961; Wilson 

 1952; Adams 1951a, b; Dingle 1956). Because of the rather abrupt change in mortality 

 rate at this time, we may consider a tree seedling established 3 years after the seed 

 has germinated or the seedling or transplant has been outplanted on the forest site. 



Losses During Establishment 



Drought is the chief cause of seedling loss during the period of establishment. 

 In a large-scale study where 90 acres were planted each year for 5 years and where 

 three classes of stock were planted on three differently prepared sites, drought was 

 believed the principal cause of mortality each year (Curtis and Coonrod 1961) . In a 

 3-year study of natural reproduction establishment, drought and insolation together 

 accounted for 64 percent of total mortality of 1-year seedlings (Foiles and Curtis 



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