DISTANCE APART. 51 



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 each 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 Kim 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 acr^e 

 as when planted 4x4 feet, but the former distance has the advan- 

 tage 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 con- 

 ditions for many years, and to that extent fall short of an impor- 

 tant 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 

 consist 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 drawbacks 

 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, when properly made, have the following 

 advantages: (i) They make possible the growing of species 

 that form a protection in the least possible time, and still have 

 coming on in the same grove longer-lived and better kinds to 

 lake their places. (2) Many kinds that are somewhat tender 

 are helped very much by being grown among the hardier kinds 

 until well established. In this case the protecting trees are 

 called nurse trees. The Scotch Pine is seldom a success when 

 standing alone on our Western prairies, but when partially pro- 

 tected by some deciduous tree it stands very well. The same 



