FORESTRY AND CONSERVATION 345 



lying such methods have been discussed in the chapter "How trees 

 grow ;" in the present chapter it is proposed to point out briefly 

 the special considerations which should guide the forest planter in 

 particular. 



What Trees to Plant. Adaptability to climate is the first 

 requisite in the species to be planted. It is best to choose from the 

 native growth of the region which is known to be adapted to it. 

 With regard to species not native, the reliance must be placed upon 

 the experience of neighboring planters and upon experiment (at 

 first on a small scale), after study of the requirements of the kinds 

 proposed for trial. Adaptation must be studied, not only with refer- 

 ence to temperature ranges and rainfall, but especially with refer- 

 ence to atmosphere humidity, requirements of transpiration and 

 height above sea level. 



Many species have a wide range of natural distribution, and 

 hence of climatic adaptation. If such are to be used, it is import- 

 ant to secure seeds from that part of the range of natural distribu- 

 tion where the plants must be hardiest, i. e., the coldest and driest 

 region in which it occurs, which insures hardy qualities in the off- 

 spring. For instance, the Douglas spruce from the humid and 

 evenly tempered Pacific Slope will not be as hardy as that grown 

 from seed collected on the dry and frigid slopes of the Rockies. Lack 

 of attention to this requisite accounts for many failures. It must 

 also be kept in mind that while species may be able to grow in an- 

 other than its native climate, its wood may not there have the same 

 valuable qualities which it develops in its native habitat. Adapta- 

 bility to soil must be studied less with reference to mineral constitu- 

 ents than to physical condition. Depth and moisture conditions, 

 and the structure of the soil, which influences the movement of 

 water in it, are the most important elements. While all trees 

 thrive best in a moist to "fresh" soil of moderate depth (from 

 2 to 4 feet) and granular structure, some can adapt them- 

 selves to drier or wetter, shallow, and compact soils. Fissures in 

 rocks into which the roots can penetrate often stand for depth of 

 soil, and usually aid in maintaining favorable moisture conditions. 

 In soils of great depth (i. e., from the surface to the impenetrable 

 subsoil) and of coarse structure water may drain away so fast as not 

 to be available to the roots. Soil moisture must always be studied in 

 conjunction with atmospheric moisture, for, while a species may 

 thrive in an arid soil, when the demands of transpiration are not 

 great, it may not do so when aridity of atmosphere is added. Trees 

 of the swamp are apt to be indifferent to soil moisture and to thrive 

 quite well, if not better, in drier soils. 



Adaptability to site. While a species may be well adapted to 

 the general climatic conditions of a region, and in general to the 

 soil, there still remains to be considered its adaptability to the par- 

 ticular "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 



