FOREST FIRE 



to be much the same as they are in 

 the South. Sprouting of hardwood 

 species is greatly reduced by summer 

 fires, and several summer fires will 

 virtually eliminate hazel, the most 

 serious and widespread competitor of 

 pine regeneration in Minnesota. 

 Spring and fall burns are less effec- 

 tive and sometimes more erratic in 

 behavior. 



Use of fire for seedbed preparation 

 in black spruce has been developed 

 through research and is now being 

 used on a limited scale. Mature 

 black spruce is cut in strips. The 

 strips are burned while the water 

 table is high. The slash and certain 

 mosses, which are a poor seedbed for 

 spruce, are eliminated and a favor- 

 able seedbed of burned peat is created 

 on most of the area. Clearcut blocks 

 are also seeded artificially following 

 prescribed burning. 



In the West, fire is used mainly 

 in Douglas fir and pine types for 

 slash disposal after harvest cutting, 

 which also prepares the area for 

 seeding or planting. 



Needs and Limitations of 

 Prescribed Fire 



While fire is a very useful tool, 

 it requires great care to apply prop- 

 erly. Its effects are not known com- 

 pletely, even in the South, and it 

 has sharp limitations. It is applicable 

 for understory control only where 

 the overstory is resistant to fire, 

 which restricts its use for this purpose 

 to the hard pine types. It has some- 

 what wider applicability for site 

 preparation. 



Use of fire in the management of 

 forests has been applied with vary- 

 ing results, some promising, some 

 disappointing. One of the main prob- 

 lems is in understanding the total 

 effects of burning in order to achieve 

 consistent results either for forest 

 reproduction or wildlife management. 



To prescribe fire for specified re- 

 sults while avoiding damages to the 



stand and site, much more informa- 

 tion is needed on the relation of fire 

 intensity to weather factors and fuel 

 conditions, and the effect of various 

 fire intensities on the vegetation and 

 soils. While research may show that 

 particular weather and fuel condi- 

 tions will produce a certain fire in- 

 tensity, such narrowly specified con- 

 ditions will occur only infrequently 

 and for limited periods. Thus, the 

 duration of the required weather and 

 fuel conditions determines the acre- 

 age that can be burned, which may 

 often be less than planned. In addi- 

 tion, fire intensity will vary with 

 vegetational and fuel types over the 

 burn areas, with corresponding varia- 

 tions in results. Because of these 

 limitations and variations, fire can 

 only be an imprecise tool at best. 

 Consequently, if fire is to be used, 

 information to prescribe it correctly 

 is essential. 



Limitations of the Southern Expe- 

 rience — It is not safe to assume the 

 effects of fire on soils observed in 

 the South are applicable elsewhere, 

 for two reasons. The frequent past 

 burning in the South may be a factor 

 in the observed soil effects — any 

 pine area used to study fire effects 

 is likely to have been burned many 

 times in the past. And soils elsewhere 

 are not comparable to those in the 

 southern pinery. Even in the South, 

 however, the available information 

 comes from only a few studies in 

 limited localities. Consequently, the 

 effects of fire on erosion, soil struc- 

 ture, chemical characteristics, and 

 soil biology should be investigated 

 along with studies of vegetational 

 effects and development of techniques 

 wherever fire is to be used. Burning 

 undoubtedly releases mineral nutri- 

 ents contained in the forest litter, but 

 these might be largely lost on slopes 

 and deep sands. Very little is known 

 about fire effects on soil flora and 

 fauna beyond their immediate de- 

 struction in the burned portion of the 

 forest floor, yet they may be very 

 important in longer-term soil produc- 

 tivity and the health of the forest 

 vegetation. 



It should be recogni . ver, 



that burning for site prep; 

 done only once in the life ol 

 stand. In southern pines, a rotation 

 (time from establishment to harvest 

 of a timber stand) may be as short 

 as 20 or 25 years. In the North and 

 West, a rotation is much longer. 

 Burning for hardwood control during 

 the rotation is done more frequently 

 and the effects on soils may be more 

 important. 



Effect of Smoke — An aspect of 

 prescribed burning that has only re- 

 cently been recognized is that smoke 

 is an effect that needs to be con- 

 sidered. Weather and fuel conditions 

 satisfying prescriptions for burning 

 may occur simultaneously over ex- 

 tensive areas and many fires may be 

 burning at the same time. Locally, 

 low-lying palls of smoke can reduce 

 visibility enough to make automobile 

 driving hazardous. People in the 

 vicinity may suffer physical discom- 

 fort. On a larger scale, one could 

 speculate that weather might con- 

 ceivably be affected by fire under cer- 

 tain atmospheric conditions. Smoke 

 particles might serve as condensation 

 nuclei, resulting in cloudiness, or the 

 smoke itself might accumulate at tem- 

 perature-inversion levels, obstructing 

 back radiation and changing tem- 

 peratures at ground level. Thus, the 

 effects of the smoke alone might pre- 

 clude prescribed burning in some 

 localities. 



Needed Scientific Activity 



Several aspects of fire ecology 

 should receive serious attention: 



1. Effects of fire or burning are 

 long-range. Published reports 

 are often based on short-term 

 studies, both in management 

 and ecology. Long-term studies 

 with both ecological and man- 

 agement emphasis are needed. 



2. There should be more integra- 

 tion of ecological and manage- 

 ment research. The two are of- 



311 



