INVESTIGATIONS OF THE ROTTING OF SLASH IN ARKANSAS. 11 



but also in Arizona and New Mexico, where the same conditions as 

 to the rotting of the limbs in the center of the piles were found to 

 exist. 1 



It is very evident that certain groups of fungi capable of rotting 

 the small twigs and branches of trees which have died in the forest 

 or of trees which have been felled are not capable of thriving under 

 the conditions found in the center of large and compact brush piles. 

 This is further accentuated by the fact that the bottoms of the brush 

 piles in Arkansas, when rotted at all, are not rotted by these fungi, 

 but are attacked by other fungi, such as Fomes annosus, which are 

 known to live in more or less shaded and underground habitats. 



What the factors are that dominate the growth and activity of 

 these various groups of fungi is not known. For instance, why 

 is it that usually Stereum rameale and S. Mrswtum rarely attack 

 limbs above 1 inch in diameter, while S. umbrinum and S. versi- 

 forme are rarely found in limbs larger than 2 or 3 inches in diameter? 

 Why do not these fungi usually attack logs and large branches? Is 

 the moisture content too high or the temperature too low? On the 

 other hand, Stereum fasciatum, the common fungus rotting the cull 

 logs and boles of the oak slash, usually does not attack the twigs and 

 small branches. Of course, the explanation for this fungus might 

 be that the twigs and small branches have not a sufficient amount of 

 moisture, but such an explanation could not be offered for the failure 

 of Stereum rameale, S. versiforme, and S. umbrinum to attack the 

 large branches and trunks. 



It would seem that but little is known concerning the real factors 

 controlling fungous activity in wood. It is evident, however, that 

 certain groups of fungi are capable of rotting the wood as it is nor- 

 mally found in nature; that is, when a tree dies, is killed by light- 

 ning, or is wind thrown. These are conditions which have been oc- 

 curring in nature through centuries, and certain fungi have adapted 

 themselves to such conditions. The same could be said of limbs and 

 logs which are in contact with the soil, or even buried in the soil, 

 since such conditions are normal and found generally in nature. 



Apparently there are no fungi capable of vigorous growth under 

 the artificial environments found in the center of large brush piles, 

 where the conditions do not approximate those existing either when 

 the brush is in contact with the soil or when it is exposed to the 

 sunlight. 



GENERAL DISCUSSION. 



Several factors, such as fire, reproduction, and the rotting of the 

 brush, are so intimately associated that it is impossible to discuss 

 any one phase of brush disposal without noting, at least briefly, the 



1 Long, W. H. Op. cit., p. 389-390. 



