388 HORTICULTURE, FORESTRY, FLORICULTURE 



feet, especially in mixed plantations and on the prairies. The very 

 purpose of close mixed planting is to force the trees to prune them- 

 selves, and they can be depended upon to do this as it becomes 

 necessary. The lower branches aid very much in making the plan- 

 tation effective as a wind-break. While small and weak, in the 

 aggregate they make a strong barrier to the wind, and should be 

 left for this purpose, if for no other. A possible exception may be 

 named in the catalpa; but even in this tree the lateral branches 

 should only be removed as they show signs of dying, and then only 

 because, being persistent and not shed after a year or so, as with 

 most deciduous trees, they make defects in the timber of the trunk. 



Thinning. Thinning trees planted 3 by 3 feet is seldom if 

 ever necessary until from five to seven years after planting; and at 

 the first thinning the removal of comparatively few trees will be 

 advisable. It may be best to head in some of these trees by clipping 

 their lateral branches in the intervals between thinning, but our 

 strong Western soils should be able to carry the full stand until 

 from five to ten years old, and the subsequent thinnings should be 

 at intervals of from seven to ten years. 



Grazing Fire. Grazing animals should be rigorously excluded 

 from all tree plantations. Even if the trees are too large to be 

 broken off by the stock, every branch within reach will be browsed, 

 and the desirable forest conditions of shade, undergrowth, and litter 

 will be destroyed. In a well-established grove stock may do little 

 harm, but until the crowns of the trees are entirely out of reach 

 cattle should not be admitted. Even then injury may result from 

 the trampling of the soil. A heavy soil becomes packed so that it 

 .is nearly impervious to water, while a sandy one is worn and blown 

 away, leaving the roots exposed. The damage to large trees in 

 situations where moisture is abundant is not usually great, and the 

 protection furnished to stock in such a case may more than offset 

 the slight injury to the trees. Every tree plantation needs to be pro- 

 tected by some form of fire guard. Where conditions permit, a very 

 satisfactory guard is made by plowing two or three furrows about the 

 plantation close to the trees and then making a second series of 

 furrows from one to two rods outside the first. These lines may be 

 kept free from vegetation by replowing each year or they may be 

 used for crops that do not easily burn. The space between the two 

 series of furrows should be kept free of all combustible material by 

 burning it over at safe times. (Y. B. 1895; F. S. Cir. 54.) 



FENCE-POST TREES. 



A forest plantation may often serve both as a woodlot and as a 

 shelterbelt for crops, stock, and farm buildings. If trees suitable 

 for fence posts are grown, they will furnish the desired protection 

 and also yield a salable product. The best species for post produc- 

 tion are chestnut, European larch, catalpa, black locust, Osage 

 orange, and Russian mulberry. None of these trees should be used 

 except within their economic planting range and on soils adapted 

 to their growth. ^ In States where several of these trees can safely be 

 planted, the choice will naturally fall on the best grower or the one 



