ENEMIES OF PLANTATIONS. 45 



several months before they are able to begin taking up moisture. 

 Even very early fall planting, which has given the trees opportunity 

 for root growth before cold weather, has yielded unsatisfactory 



results. 



ENEMIES OF PLANTATIONS. 



Forest protection is everywhere recognized as one of the chief 

 functions of forestry, and especially so in the United States with its 

 virgin forests, but it is nowhere of greater moment than in the sand 

 hills. Almost every kind of forest enemy has been encountered since 

 planting w T as begun in Nebraska. Of the enemies of the embryo 

 forest nothing can be considered of so great import as fire. 



FIRE. 



Probably for centuries the prairie fire has been the expected, and 

 sometimes the desired, thing in the sand-hill region. Prairie fires 

 temporarily improve grazing conditions by destroying the old grass, 

 which has no forage value, and making room for a more vigorous 

 growth of the new grass. But they undoubtedly have done the 

 sand hills permanent injury by destroying the humus which other- 

 wise would have collected in the soil and would have improved its 

 composition and productivity. The most destructive prairie fires 

 come in the early spring before new grass has sprouted. Even the 

 lightest of fires destroys small coniferous trees, which burn readily, 

 though jack pine at Halsey has sometimes recovered after a light 

 scorching. 



To protect the plantations properly requires constant care during 

 the danger season and the preparation each year of plowed fire lines. 

 As with most fire lines, these are valuable principally as a basis for 

 back-firing and can not be depended upon to check a fire. For 

 complete safety from outside fires all of the plantations are sur- 

 rounded by double guards, consisting of two strips of furrows with a 

 grassy strip between them from 60 to 100 feet wide, which is burned 

 off annually. Then, there is the additional problem of protecting 

 from fires which may arise within the plantation, either as a result of 

 lightning or through the carelessness of laborers and hunters. This 

 internal protection is afforded to the plantation as a whole by divid- 

 ing it into tracts of 40 acres or more, separated by fire lines. While 

 absolute protection is hard to achieve, the fire danger will decrease 

 somewhat as the trees become older and more resistant and as the 

 grass is shaded out. As soon as the trees become so large that they 

 will not be broken off or browsed stock may be used to keep the 

 grass down. 



INSECTS. 



The only destructive insect which has appeared in the Nebraska 

 plantations is the Nan tucket pine-tip moth (Retiniafrustrana), which 

 appeared in 1909. Similar insects had been noted in the Pine Ridge 



