122 



and develop well as an understory in 

 a well-stocked stand of larger trees, 

 while intolerant trees are those that 

 cannot survive such a subordinate 

 position. 



From the examples I have cited, it 

 is apparent that species such as sugar 

 maple, white spruce, and the lowland 

 white fir are very tolerant of shade, 

 jack pine and loblolly pine are rather 

 intolerant, and western larch and east- 

 ern red oak have intermediate ratings 

 in the scale of tolerance. 



SEEDING CHARACTERISTICS of trees 

 are also important in arriving at work- 

 able methods of forest renewal. 



The means of natural dissemination 

 of seed are key factors and can be 

 divided into two major groups. The 

 largest group is the light-seeded species 

 whose seed can be disseminated by the 

 wind. Seed of these species are attached 

 to wings, downy material, or other 

 structures that aid in distribution by 

 the wind. In this group are the pines, 

 spruces, and firs, and many important 

 broadleaved species such as the yellow- 

 poplar, the ashes, maples, birches, elms, 

 poplars, and others. The second group 

 consists of heavy-seeded species whose 

 seed is distributed only by gravity, with 

 some rather ineffective aid by birds and 

 animals. This class includes the oaks, 

 walnut, hickories. Obviously with these 

 there can be little lateral distribution 

 from the parent tree by wind. Hence, 

 with this group, the trees chosen to 

 reseed an area must be more closely 

 spaced than with the group whose seed 

 is wind-borne. 



Seed-producing capacity is another 

 important characteristic to be con- 

 sidered. It may be poor because the 

 intervals between the good seed years 

 may amount to as much as 6 or 7 years 

 (with species such as red pine, longleaf 

 pine, and beech) or because not much 

 seed is produced, as is the case with 

 chestnut oak. Other species (such as 

 Virginia pine and scarlet oak) bear 

 good crops every year or two. 



Many other seeding characteristics 

 are of importance. One is the time over 



Yearbook^ of Agriculture 1949 



which seed is dispersed. Some species, 

 like white pine and the firs, spread 

 their seed within a few days or weeks. 

 Others, such as loblolly pine, spread a 

 considerable portion within a few 

 weeks, but continue to shed significant 

 quantities of seed for several months 

 after the cones open. Still others, such 

 as jack pine, lodgepole pine, and pond 

 pine, retain seed in persistent cones for 

 several years, shedding few or none 

 until opened either by the heat of a 

 fire or by exposure, after felling, to the 

 high temperatures that exist near the 

 soil surface in midsummer. 



As in basic requirements, seeding 

 characteristics vary widely between the 

 species, and knowledge of them is 

 needed by anyone who wants to ac- 

 complish forest renewal. 



As TO CUTTING i I mentioned earlier 

 that forest renewal is an integral part 

 of the harvesting process and how 

 readily light and associated factors can 

 be modified by cutting. Seeding char- 

 acteristics, too, can be taken advantage 

 of by cutting, because relatively few 

 trees are needed for regeneration pur- 

 poses where species produce good crops 

 of wind-borne seed. 



The knowledge of a species and its 

 requirements, coupled with the tools 

 of logging, are the basic equipment for 

 successful forest renewal. 



A forest composed of the tolerant 

 species, that is, those that develop well 

 in an understory position, if they are 

 protected from fire and grazing, will 

 contain on a single acre trees of many 

 sizes and ages. To the layman it may 

 present an unkempt appearance, and 

 his first reaction may be a desire to 

 clear away the underbrush. The wood- 

 land manager who deals with such a 

 forest feels fortunate, because his prob- 

 lems of forest renewal are relatively 

 simple and almost automatic. In this 

 type of forest, the scattered individual 

 mature trees or small groups of them 

 are removed at intervals along with 

 the deformed, diseased, overcrowded, 

 or otherwise unneeded trees. The rate 

 of such cutting is prescribed by a 



