INVESTIGATIONS OF THE ROTTING OF SLASH IN ARKANSAS. 5 



BRUSH WHEN PILED. 



White-oak brush piles were examined, ranging from 1 to 5 years 

 in age. During the first year after the trees were cut hut little evi- 

 dence of rot could be seen except a discoloration of the sapwood. By 

 the end of the second or third year all of the leaves had fallen from 

 the twigs which were exposed to the sun's rays, and the brush at the 

 tops and sides of the piles where exposed to the sunlight had rotted 

 to some extent, while the slash in the middle of the piles not in actual 

 contact with the ground and yet protected from the sunlight was 

 rotted but slightly, if at all. The twigs and small branches at the 

 bottoms of the piles were more or less rotted by certain other fungi 

 (called "ground" fungi in this bulletin), which apparently entered 

 these branches from the soil. These ground fungi seem to rot the 

 brush more rapidly and more thoroughly than the regular slash-, 

 rotting fungi. 



Usually there is but little evidence of rot in the center of the piles 

 during the first four years after piling. However, around the edges 

 and through crevices in the top the sunlight sometimes penetrates 

 sufficiently to permit slight fungous growth. Nevertheless, there is a 

 marked difference between the rotting of the brush in the center of 

 the piles not adjacent to the ground and that at the top and bottom 

 of the pile. 



By the end of five years the top and bottom of the piles have rotted 

 to a considerable extent, while the brush in the center of the piles, 

 where it had become more or less exposed to the sun's rays, was 

 beginning to rot. 



For the brush in the center of the piles to rot completely it appar- 

 ently (1) must be brought within range of the soil moisture by the 

 rotting of the brush below it and by the settling of the pile, or (2) 

 the upper portion must disintegrate sufficiently for the sun's rays to 

 reach the center of the pile. Undoubtedly, both conditions finally 

 develop and aid in the rotting of the brush which was originally in 

 the center of the piles. 



In a white-oak brush pile the layer of brush at the bottom would 

 be the only one even in partial contact with the soil, while the 

 remainder of the pile would be held from the soil by this first layer 

 and therefore could not receive any benefit from the soil moisture. 

 Neither are the piles dense or compact enough to raise the moisture 

 content of the air around the brush in the piles sufficiently to encour- 

 age the growth of the ground fungi in branches not in actual contact 

 with the soil. On the other hand, the brush not in contact with the 

 soil in the piles and yet sheltered from sunlight is deprived of the 

 activity of the fungi which normally rot slash in the open; that is, 

 slash when left as it falls in the tree tops. 



