20 BULLETIN 153, U. S. DEPARTMENT OF AGRICULTURE. 



Snow and frost may also cause considerable damage; the former 

 weighs down and breaks off branches and leaders; the latter, when 

 occurring late in spring or early in autumn, may kill the succulent 

 wood. Damage from snow is less likely with hardwood trees than 

 with conifers, because the bare branches of the former do not permit 

 as much of it to accumulate. Frost damage may be partly avoided 

 by planting hardy species or by utilizing sites on north, northeast, or 

 northwest slopes, where growth begins comparatively late in spring 

 and stops early in the fall. Low sites on which there is poor circu- 

 lation of air should be avoided. 



GRAZING ANIMALS. 



Sheep, cattle, or horses should never be allowed in a young planta- 

 tion. They browse upon leaves and tender shoots and trample the 

 trees, which become crooked, branchy, and dwarfed. If pasturing is 

 continued the trees will eventually be killed. Bulletin 200 of the 

 Wooster (Ohio) Agricultural Experiment Station, sums up, for Ohio, 

 the damage from this source : 



The acres of young forest which have been needlessly destroyed within the State 

 foot up into the millions. Their value, had they been protected from live stock, would 

 to-day amount to double the sum which has been realized from the pasture. This is 

 demonstrable, for the investigations of the experiment station have shown that the 

 value of young forest- tree growth exceeds the value of woodland pasture more than 

 two to one. There is no such thing as profitable woodland pasture. The combination 

 of grass and forest is incompatible. Cattle derive but little, if any, benefit from brows- 

 ing or from the shaded innutritious grasses, but they do damage the trees. The losses 

 from this practice are larger to-day than ever before because of the constantly increas- 

 ing value of the trees which are destroyed. 



In a plantation of green ash at Kanaw^ha, Iowa, trees which had 

 been protected from cattle were from 10 to 17 feet high, while others 

 of the same age which had been browsed by cattle were for the most 

 part only 4 feet high. In a 5-year-old plantation of black locust in 

 Michigan, grazed by both sheep and cattle, ungrazed trees had 

 reached an average height of from 8 to 14 feet, when those browsed 

 by the stock were only from 2 to 3 feet high. In a 10-year-old plan- 

 tation of black walnut in Indiana, grazed by cattle, 25 per cent of the 

 living trees had been broken by stock, and averaged from 5 to 6 feet 

 in height; the unbroken trees were from 19 to 25 feet high. The 

 owner stated that the trees were pretty well tramped out at one time, 

 which accounts for the fact that of the trees originally planted 78 per 

 cent are now missing. 



In older plantations the damage done by stock consists largely in 

 packing of the soil. As a result of the stock running at large, the 

 humus is destroyed and the roots of the trees exposed and perhaps 

 wounded, while the soil becomes impervious to water. The stand, of 

 course, suffers accordingly. Moreover, fungi may enter the trees 

 through wounds around the base or in the roots. 



