44 ELEMENTARY FORESTRY. 



each way with the idea that when so planted they would quick- 

 ly shade the ground and consequently keep out grass and re- 

 tard evaporation. Some successful plantings have been made 

 on this plan, but when planted so closely together the branches 

 grow into the rows after a few years and cultivation must be 

 discontinued. In this section where we have so much very 

 bright sunshiny weather that grass can grow under foliage 

 that would kill it out in a more humid climate, we find that 

 trees planted four feet apart ea.ch way seldom afford sufficient 

 shade to kill the grass under them for many years. This is 

 especially true of such trees as the Cottonwood, Lombardy 

 Poplar and White Elm when planted alone as they have open 

 foliage that does not furnish a dense shade. Among tree 

 planters who have had a large experience in prairie planting 

 there has been a tendency of late years to plant two feet apart 

 in rows eight feet apart, and some of our most successful 

 planters prefer even more room than this between the rows. 

 When plantings are made 2x8 feet the same number of trees 

 are required for an acre as when planted 4x4 feet, but the, 

 former distance has the advantage over the latter in that the 

 space between the rows can be cultivated for perhaps ten years 

 or more by which time most trees will have formed a dense 

 shade and be able to take care of themselves. Where a much 

 greater distance than eight feet is allowed between the rows 

 we generally fail to get forest conditions for many years and 

 to that extent fall short of an important requisite in prairie 

 planting. The distances given here might need to be modified 

 to suit different varieties and local climatic conditions. 



Clear Plantings. Most of the plantings on our prairies con- 

 sist wholly of one kind. In some cases good results are thus 

 obtained but they are seldom as satisfactory as plantings 

 made up of several different kinds. One of the greatest draw- 

 backs to plantings made up entirely of one kind is the fact 

 that drouth, insects or fungous disease may destroy the whole 

 planting at one time while in a judiciously mixed planting 

 this could hardly occur. 



Mixed Plantings. The mixing of different varieties of trees 

 in prairie planting is so important that it should be very 

 carefully considered by planters. The European foresters, in 



