278 FORESTRY INVESTIGATIONS IT. S. DEPARTMENT OF AGRICULTURE. 



particular " site/' under which term we may comprise the total effect of general climate, local 

 climate, and soil. The general climatic conditions are locally influenced, especially by the slope, 

 exposure, or aspect, and the surroundings. Thus we know that eastern exposures are more liable 

 to frost, western exposures more liable to damage from winds, southern more apt to be hot and to 

 dry out, and northern to be cooler and damper, having in consequence a shorter period of vegeta- 

 tion. Hollows and lowlands are more exposed to frosts and more subject to variations in soil 

 moisture, etc. 



Hence for these various situations it is advisable to select species which can best withstand 

 such local dangers. 



The use value, or utility, of the species is next to be considered. This must be done with reference 

 to the commercial and domestic demand, and the length of time it takes the species to attain its 

 value. The gi eater variety of purposes a wood may serve— i. e., the greater its general utility — 

 and the sooner it attains its use value, the better. White pine for the northeastern States as a 

 wood is like the apple among fruits, making an all-round useful material in large quantities per 

 acre in short time. Tulip poplar, applicable to a wider climatic range, is almost as valuable, while 

 oak, ash, and hickory are standard woods in the market. Other woods are of limited application. 

 Thus the black locust, which grows most quickly into useful posts, has only a limited market, 

 much more limited than it should have; hickory soon furnishes valuable hoop poles from the 

 thinnings, and later the best wagon material, not, however, large quantities in a shoit time; while 

 black walnut of good quality is very high in price, the market is also limited, and the dark color 

 of the heartwood, for which it is prized, is attained only by old trees. The black cherry, used for 

 similar purposes, attains its value much sooner. 



By planting various species together, variety of usefulness may be secured and the certainty 

 of a market increased. 



The forest value of the species is only in part expressed by its use value. As has been shown 

 in another place, the composition of the crop must be such as to insure maintenance of favorable 

 soil conditions as well as satisfactory development of the crop itself. Some species, although of 

 high use value, like ash, oak, etc., are poor preservers of soil conditions, allowing grass and weeds 

 te enter the plantation and to deteriorate the soil under their thin foliage. Others, like beech, 

 sugar maple, box elder, etc., although of less use value, being dense iohaged and preserving a 

 shady crown for a long time, are of great forest value as soil improvers. 



Again, as the value of logs depends largely on their freedom from knots, straightness, and 

 length, it is of importance to secure these qualities. Some valuable species, if grown by themselves, 

 make crooked trunks, do not clean their shafts of branches, and are apt to spread rather than 

 lengthen. If planted in close companionship with others, they are forced by these "nurses" or 

 "forwarders' 7 to make better growths and clean their shafts of branches. 



Furthermore, from financial considerations, it is well to know that some species develop more 

 rapidly and produce larger quantities of useful material per acre than others; thus the white 

 pine is a "big cropper," and combining with this a tolerably good shading quality, and being in 

 addition capable of easy reproduction, it is of highest "forest value." 



Hence, as the object of forestry is to make money from continued wood crops, use value and 

 forest value must both be considered in the selection of materials for forest planting. 



Mutual relationship of different species, with reference especially to their relative height growth 

 and their relative light requirements, must be consideied in starting a mixed plantation. 



Mixed forest plantations (made of several kinds) have so many advantages over pure planta- 

 tions (made of one kmcl) that they should be preferred, except for very particular reasons. Mixed 

 plantations are capable of producing larger quantities of better and more varied material, preserve 

 soil conditions better, are less liable to damage from winds, fires, and insects, and can be more 

 readily reproduced. 



The following general rules should guide in making up the composition of a mixed plantation : 



a. Shade-enduring kinds should foim the bulk (five-eighths to seven -eighths) of the plantation, except on 

 specially favored soils, where no deterioration is to he feared from planting only light-needing kinds, and in which 

 case these may even he planted by themselves 



b. The light-needing trees should be surrounded by shade-enduring of slower growth, so that the former may 

 not be overtopped, but have the necessary light and be forced by side shade to straight growth, 



