ARBORICULTURE 



49 



Wind carries the leaves to other fields, 

 adding- in their fertilization. 



The waste in soil erosion is greatly 

 lessened, and often checked entirely. 



The injurious effects of hot drying 

 winds is largely overcome by heavy belts 

 of trees, which guide the air currents 

 above the surface. 



The influence of the trees upon the 

 climate, rainfall and sudden changes of 

 temperature is recognized by every in- 

 telligent person. 



A forest of economic trees is better 

 than a life insurance policy, for a great 

 majority of companies fail aTter receiv- 

 ing premiums for many years. 



TABLE OF ANNU.AL GROWTHS. 



Careful measurements made by the 

 writer in the last thirty years, and obser- 

 vations in nearly all the states in the 

 Union, establish the fact that young and 

 thrifty trees develop very rapidly, many 

 species enlarging their trunk diameter 

 one inch each year up to the twentieth 

 year, after which, owing to the exhaus- 

 tion of plant food within reach, and 

 interference by roots of adjacent trees, 

 the growth is somewhat diminished. 



Average annual increase in girth after 

 planting : 



\sh 2.8 



Birch 44 



Buckeye 2.1 



Chestnut . . 2.9 



Catalpa 3.4 



Cottonwood . . 5.0 



Elm, American 3.2 



Hemlock 1.7 



Hickory 2.4 



Honey Locust . . 3.0 



Kentucky Coffee 2.6 



Larch 3.0 



Locust 4.0 



Lombardy Poplar 5.5 



Linn 3.3 



Maple, White 5.8 



Maple, Norwaj' 2.0 



Maple, Sugar .... 2.1 



Mulberry 4.0 



Oak. Red 3.;:^ 



Oak, Black 2.3 



Oak, Burr .... • • 2.5 



Oak, Willow 2.5 



Pine, White . . 2.2 



Sweet Gum 2.6 



Sycamore 3.9 



Spruce, Norway 2.4 



Tulip Trees 2.7 



Weeping Willow 7.0 



Wild Cherry 1.8 



Erosion. 



NOTHING remains stationary in 

 nature. Changes are constantly 

 occurring. Worlds move con- 

 stantly in their orbits through the hea- 

 vens. The earth ever continues to tear 

 down the wondrous monuments of past 

 epochs, and to erect new geological for- 

 mations. One great force of nature 

 upheaves the land at one place, depress- 

 ing it elsewhere, and in these operations 

 mountain chains are elevated, volcanoes, 

 earthquakes seismic exhibitions are but 

 partial effects of this enormous force. 

 Another element is at work tearing down 

 the mountains, leveling the hills and 

 sweeping down to lower levels the looser 

 portions of the surface, from the moun- 

 tain* plain and valley. This power is 

 erosion. 



Alternate freezing and thawing of the 

 water on the higher mountains rend 



asunder the granite rocks, and hurl them 

 far down the valleys ; torrents of water 

 roll these fragments along the mountain 

 streams, grinding them into powder, 

 which is borne by the currents to the 

 ocean. This same power, flowing water, 

 washes the soil from ten thousand farms, 

 and mingles it with the debris from 

 granite peaks ; strewing it about the 

 deltas of all great rivers. 



It is this erosion, by flowing waters, 

 that so constantly channels out the farms 

 on rolling lands, and removes the richest 

 portions of fertile fields of every thrift- 

 less farmer. The tendency to clear away 

 all forest growths from every steep hill- 

 side, to bare the banks of every stream, 

 for the purpose of obtaining a few crops 

 while the land is new and the soil fertile, 

 is destructive of farm lands and a very 

 injurious practice. 



