608 



Yearboo\ of Agriculture 1949 



or the soil surface, so as to maintain 

 maximum possible rates of infiltration 

 of water into the mantle. Harvesting 

 methods should also provide for the 

 encouragement of the species that are 

 capable of transpiring large quantities 

 of water and thus maintain the great- 

 est storage capacity in the mantle. 



Logging operations can and often do 

 cause serious watershed impairment, 

 even though they leave the stand in 

 satisfactory condition for natural re- 

 generation. The chief injury is that 

 brought about by the clearing and 

 compaction of the soil along skid trails 

 and haul roads. Compaction and con- 

 sequent abnormally rapid surface 

 runoff is known to persist for many 

 years even though the land is quickly 

 revegetated. Skid trails and similar 

 disturbances to the soil should be held 

 to a minimum. There should be ade- 

 quate provision for the immediate 

 stabilization of loosened soil, for the 

 safe handling of drainage, and for the 

 reestablishment of plant cover so as to 

 prevent excessive runoff and acceler- 

 ated erosion. Where these watershed 

 maintenance requirements cannot be 

 met, there should be no logging. 



The most difficult of all watershed- 

 management jobs is to maintain satis- 

 factory watershed conditions on an 

 area heavily grazed by livestock and big 

 game. Many have considered this 

 solely a western problem. But that is 

 erroneous, for serious grazing-water- 

 shed problems exist in the Central 

 States, in the South, and in the East. 



The chief thing to avoid is overgraz- 

 ing. When the livestock overcrop the 

 herbaceous and shrubby forage, the 

 ground surface is bared to the direct 

 impact of the rain. This condition 

 opens the canopy, permitting the sun's 

 rays to hasten the disintegration of lit- 

 ter on the ground. Consumption of the 

 forage, though it puts pounds on the 

 grazing animals, robs the soil surface of 

 its normal annual accumulation of 

 dead grass stalks and leaves. Continued 

 over the years, this further exposes the 

 soil surface. In addition, the hoofs of 

 the grazing animals compact the soil 



or push it down hill. All these effects 

 lower the capacity of the land to soak 

 up and store water and therefore favor 

 destructive overland flow, accelerated 

 erosion, and greater sediment loads in 

 the streams. 



Overgrazing results in progressively 

 serious stages of watershed deteriora- 

 tion. With each decrease in the capac- 

 ity of a site to take up and store water, 

 less precipitation is required to cause 

 overland flow and accelerated erosion. 

 Once the processes of deterioration get 

 under way, there is less and less control 

 of runoff and more and more soil loss. 

 Thus, without any change of climate, 

 watershed impairment results in more 

 and larger storm flows and greater 

 sediment loads. 



The maintenance of satisfactory 

 watershed conditions under grazing re- 

 quires extreme care in the handling of 

 stock on the range and in the location 

 and use of driveways, water develop- 

 ments, salt grounds, bed-grounds, and 

 similar stock-control devices so as to 

 give a minimum of soil disturbance and 

 depletion of the plant cover. Grazing 

 use should be avoided when the soil is 

 wet, particularly on sites that are sus- 

 ceptible to compaction. In some places 

 satisfactory conditions can be main- 

 tained by postponing grazing until after 

 the season of high-intensity storms. 

 Great care is needed to make certain 

 that safely grazeable portions of a range 

 can be used without causing impair- 

 ment to adjacent lands. 



Finally, there is need for adequate 

 and frequent inspections. They should 

 be made by men who can determine 

 accurately the effect of grazing on the 

 condition and trend of the range. They 

 must not be limited solely to considera- 

 tion of the forage plants but must also 

 give adequate consideration to the soil 

 and its litter surface. Inspections must 

 be followed by prompt remedial action. 



The achievement of effective water- 

 shed management is a big task, but it 

 is not hopeless. We have learned much 

 by observing the effects of unplanned 

 exploitation of our forest and range 

 lands. Research in different parts of the 



