FARMERS' INSTITUTES. 85 



One of the most serious mistakes in woodlot management lias been the 

 pasturing of stock within its limits. The injury done may be great 

 or little according to the severity of the grazing, the topography and the 

 soil, the character of the stand, and the condition of the margin (open or 

 close) . To be very brief, grazing is injurious in two ways : 



1. It directly destroys the reproduction, and 



2. It indirectly lessens the supply of moisture in the soil. 



In regard to the first it is evident that with no regeneration of the 

 timber trees to take the place of those removed it is merely a matter 

 of time when the end must come, and the time when the stand will be 

 too open may be very soon at hand. The evil effect of this open condition 

 on the remaining stand will be discussed below\ The effectiveness of 

 grazing "in destroying reproduction will "depend naturally on the severity 

 of the grazing, or, in other words, on the number and kind of stock in the 

 woods. Goats are of course the most destructive, having a proverbial 

 fondness for the terminal buds. Next must be placed the fine-wooled 

 sheep, then coarse-wooled sheep, next horses and least destructive the 

 cattle. 



The injury to, the moisture supply of the soil by grazing is largely 

 due to the unchecked sweep of the winds through the woodlot in the 

 absence of any undergrowth. The loss of moisture is due to direct evapo- 

 ration and to the blowing of the fallen leaves, which should form a 

 natural mulch over all the surface of the soil, into heaps or entirely out of 

 the lot. The absence of this leaf cover also permits a more vigorous 

 ^'owth of moisture-robbing grasses on the forest floor. The treading of 

 the stock is also more or less destructive to the leaf mulch, and firms the 

 upper layers of the soil, thereby increasing the surface run-off during 

 heavy summer showers. 



Closely related to the injury done by grazing is the condition of the 

 margins of the lot which are exposed to the prevailing dry summer winds, 

 viz., the west and south margins. If these margins are protected by a 

 band of evergreens or even a heavy growth of low broad-leaved trees the 

 injury done to the soil moisture by grazing will be greatly reduced, and 

 vice versa, if the margins lie open the drying out of the soil will be greatly 

 increased. The open margin is a very serious defect of the average 

 Michigan woodlot. 



The fourth defect that I shall mention which is of very general occur- 

 rence is the too open condition of the average woodlot stand. In most 

 cases this has been the direct result of the axe aided by grazing. In some 

 cases it has been the result of a misguided effort to improve the woodlot, 

 and in not a few cases it has been gradually brought about by the 

 simple removal of the trees as they died — a result of depleted soil mois- 

 ture from one or more of the many causes that bring this about. What- 

 ever the cause, the results are disastrous. The striking of the sunlight 

 directly on -the forest soil stimulates the growth of grasses and other 

 moisture robbing herbs on the forest floor; it oxidizes the hvimus in the 

 soil thereby reducing its capacity to retain moisture, and it raises the 

 soil temperature, increasing the direct evaporation from the soil. The 

 influence of the light on the lower part of the crowns of the trees stimu- 

 lates an abnormal development of leaves and branches in that region, 

 often causing the so-called "water-sprouts" to develop from the trunk* 

 itself. These all tend to rob the top of the tree of needed moisture, and 



