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 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 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 ect 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: (1) 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 
take 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 
