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In addition to chemical and physical properties of 

 the soil, suggested mechanisms for the retention of 

 nutrients after fire are: 1) recovery of herbaceous and 

 woody plants, 2) increased microbial assimilation, 

 perhaps involving altered species composition, 3) 

 increased growth of fungal rhizomorphs and fruiting 

 bodies, and 4) lichen and algal growth. Many factors, 

 notably fire intensity, affect post-fire nutrient 

 redistribution, causing individual sites to respond quite 

 differently after burning. 



Ecologists have noted that certain plant communities 

 have evolved with frequent fires, and such disturbances 

 perpetuate early successional stages. Prescribed fire, 

 then might be used to maintain subclimax forests such as 

 pine or oak. In dry climates of the western U.S. where 

 fire has been excluded, forest debris can accumulate to 

 hazardous levels, ultimately resulting in severe 

 wildfire. Periodic light fires reduce fuel and prevent 

 such disasters. Prescribed burning at short intervals 

 has been used in forestry practice for site preparation 

 and stand improvement in the southern U.S. The term 

 "prescribed burn" can be defined as fire set for the 

 purpose of burning fuels that naturally occur on the 

 forest floor, while "slash burning" following timber 

 harvest involves a much heavier concentration of fuel and 

 hotter fires. Both burning practices have been found to 

 be less expensive and may have less impact on forest 

 soils than compaction from heavy machinery, or wildfire 

 resulting from fuel accumulation. 



The utility of prescribed burning and its potential 

 effects in northern forests have not been established. 

 Several uses in southern New Hampshire are currently 

 under investigation. Prescribed fire has potential in 

 suppressing understory hardwood regeneration that 

 competes with larger, fire-resistant trees like white 

 pine, or impedes establishment of desired regeneration. 

 Improvement of wildlife habitat may result when trees and 

 shrubs respond to fire by sprouting at the ground level, 

 increasing availability and, perhaps, nutrient content of 

 succulent browse. If fires mobilize elements without 

 causing detrimental loss, increased levels of plant 

 nutrients might be channeled into tree growth as well. 



In New Hampshire forests, accumulated, slowly 

 decomposing surface organic material is an important 

 reservoir of potentially available plant nutrients and 

 contains a high concentration of plant roots. The 

 organic forest floor is often subdivided into 3 horizons: 

 1) L (litter) 2) F (fermentation) , 3) H (humif ication) . 

 Alternatively the organic horizons are designated as 01 

 (litter) and 02 (F + H) . Of the 3 horizons, the F is the 

 site of most active biological decomposition. Fires 

 which destroy this layer may begin to deplete the site's 

 nutrient pool, or diminish the ability to retain 



