141. 



parts of the west over large are*s. The "beetle hinders the black locust 

 all thru the eastern United States. The gypsy moth is now endangering 

 all the spruce all over the United States. The bark disease of the 

 chestnut threatens to annihilate it. The fungus Pisisa stopped the ex- 

 tension of -'uro^ean larch in Germany and France. The bamboo exterminates 

 whole forento in part? of the tropics. The Sphagnum moss has and is now 

 destroying million* of acres of forest. 



f . This matter is wore serious on poor soil and in cold cli- 

 mates because here we have little choice of species. Those same condi- 

 tions' are found in hot countries: moss in the north, chaparral in Cali- 

 fornia, bamboo and cnnes in the tropics. 



g. En general the forest is not driven out permanently by 

 other biotic factors. The forest is itself a tremendous biotic factor. 

 But it may be temporarily driven o.it, except in the cases of Sphagnum 

 and chaparral, which are on or less permanent. The extent of the effect 

 is therefore not emtim-vtaole, in general. Buffalo and other game animals 

 furnishc food, multiplied and became potent biotic factor :, together 

 with grazing animals, 'as they prob-bly checked forest growth and encour- 

 aged grasses. The fringe forest was restricted. 



Dually the effect is the loss of one or tv;o species and a tem- 

 porary change in composition. 



Biotic factor- are universally and always on hand; they every- 

 where tend to interfere Kith growth, with development in size and form, 

 and with reproduction. They are as import-nt to the woods as soil. 



2. Fungi and larger plants (herbaceous). 



>?/ fungi and bacteria actually help trees; most of them injure 

 trees. /-11 wood-destroying fungi are a necessary scavenger feature in th< 

 economy of the forest. It is necessary for Nature to employ such agents. 



^. Insects and larvae arc generally injurious, and next to man 

 .T. the great enemy of the forest. They are, however, useful as side 

 factor^ in regard to cross-f ertilization, and they are an especially tre 

 mendous factor in fighting each other. They may be adapted, therefore, ai 

 biotic factors in combating injurious insects. 



4. Rodents and browsing animals are generally injurious, but of- 

 ten are~useful bictic factors. Beechnuts and other seeds are frequently 

 planted by these animals, &&&&& including squirrels. Larger animals 

 act as a check on insect ravages. 



. Man is an important regulator and the worst destroyer of the 

 forent. He has removed the forest over enormous areas, he has destroyed 

 it by fire, he has used its wood, and introduced new species. 



Pf Classify, Judge, and Use the Site. 



A good reference is Hilgard, page 48? and following. Copy the 

 t-'ble from page 497 in that book. 



1.. Usually we classify sites in five classes. Ordinarily three 

 claf. ses"""are sufficient. 



a. The classif ication of site by volume of useful material is 

 scientific~and probably will be the final form everywhere. It is dif 

 cult to apply in the wild- oods because stands growing under reasonably 



