The surface inch of soil had slightly, but significantly, higher water content 

 under heavier concentrations of slash, probably because of less evaporation from the 

 soil due to greater shading. Soil water averaged 28 percent under heavy slash and 

 26 percent under light slash. 



Soil Temperatures 



Prescribed fires caused little heating within the surface soil (table 3). The 

 clearcuts and groups of small clearcuts burned more completely than the burned shelter- 

 wood cutting. Soil heating was greatest at the soil surface on block 23 (upper clear- 

 cut), where 60 percent of the sample points reached at least 113°F (45°C) ; only 20 

 percent of these points reached 138°F (58.9°C) (near the lethal temperature for living 

 plant tissue). The greatest depths that reached m'F (45°C) and 158°F (58.9°C) were 

 2.4 inches (6.10 cm) and 1.4 inches (3.56 cm), respectively. Rarely did the surface 

 soil reach 200°F (93.3''C) . 



Root Mortality 



Low soil warming associated with the prescribed fires caused low root mortality, 

 even within the surface 1 inch of soil (table 4) . Least root mortality occurred under 

 the shelterwood cutting where much of the block failed to burn. Because of the low 

 root mortality near the surface, recovery of perennial plants from root sprouts was 

 prolific in 1976 on all burned areas. 



Table --Maximum and average soil depth that reached or exceeded three temperatures as estimated 

 by Tempilaq melt during prescribed fires, September 1975, Coram Experimental Forest 



Block 





Sample 

 points 

 burned ^ 





113°F 







138°F 







200°F 





: Max 



: Ave : 



Points 



: Max 



: Ave 



Points 



: Max 



: Ave 



Points 







Percent 



— Inches — 



Percent 



— Inches — 



Percent 



— Inches — 



Percent 



Shelterwood ^ 



(11) 

























Shelterwood 



(21) 



30 



1.3 



0. 1 



10 



0.6 



<0. 1 



10 



0.0 



0.0 







Small Clearcuts 



(12) 



85 



1.4 



_ 2 



45 



.6 



.1 



20 



_ 2 



< .1 



5 



Small Clearcuts 



(22) 



85 



.0 



.0 







.0 



.0 







.0 



.0 







Clearcut 



(13) 



100 



.8 



2 



55 



. 3 



< . 1 



15 



.0 



.0 







Clearcut 



(23) 



90 



2.4 



. 3 



60 



1.4 



. 1 



20 





< .1 



5 



^Twenty points sampled in each block. 

 ^Shelterwood block 11 not burned. 



Table 4 .- -Mortality of nonconifer roots (percent) in the surface 

 inch of soil, before and after prescribed burning, by 

 cutting method. Coram Experimental Forest 1975 



: Living roots : Mortality 



Cutting method : Before : After : (difference) 



Shelterwood 



(H) 



90 



i _ _ 



1 _ . 



Shelterwood 



(21) 



82 



76 



6 



Small clearcuts 



(12) 



95 



69 



26 



Small clearcuts 



(22) 



88 



50 



38 



Clearcut 



(13) 



80 



44 



36 



Clearcut 



(23) 



92 



76 



16 



Not burned. 



11 



