FORESTRY 



The forest industry harvests and manages forests and processes wood products. 

 These activities generate waste (e.g., slash on site and effluents from 

 processing plants) and modify habitats (e.g., clear cutting and use of 

 herbicides). The forest industry primarily affects the terrestrial, 

 lacustrine, palustrine, and riverine systems; although the estuarine system is 

 affected locally by waste products from paper mills and wood products 

 industries (i.e., mills along the Presumpscot, St. Croix, and Penobscot 

 Rivers) and by receiving wastes that originate upstream. 



Harvesting practices employed in Maine are discussed in chapter 19, 

 "Commercially Important Trees." Two major methods are employed: uneven-aged 

 management and clearcutting. Uneven-aged management employs a selective 

 harvest system, removing only selected, mature trees that normally would be 

 lost through natural mortality. This harvest system is best for regenerating 

 shade-tolerant tree species, because it maintains a closed canopy at all 

 times. Selective harvest usually does little damage to forest systems. Some 

 disturbance of the forest floor and understory vegetation by machinery and 

 road construction does take place, however. These disturbances could affect 

 threatened and rare forest plants (see chapter 20, "Endangered, Threatened, 

 and Rare Plants"). Opening the forest canopy may affect songbird density and 

 the species composition of wildlife (see chapters 16 to 18). Streams and 

 palustrine wetlands may be affected adversely by road construction, which 

 increases siltation and alters drainage patterns. 



Clearcutting severely alters water and nutrient cycles, interrupting patterns 

 of productivity, biomass accumulation, decomposition, and mineralization. 

 Removal of the forest canopy increases solar radiation, raising soil and water 

 temperatures. Removal of trees curtails transpiration, thereby reducing the 

 rate at which water is removed from the soil and temporarily raising the water 

 table. Higher soil temperature and moisture levels promote accelerated 

 nitrification and decomposition of litter, which releases more nutrients into 

 the available nutrient pool. The forest vegetation no longer participates in 

 the flow of water through the systems, resulting in increased losses of water 

 to streamflow and higher peak runoff during storms. Increased runoff 

 aggravates the erodibility of the forest floor, which increases particulate 

 matter and nutrient loss in the local ecosystem. A detailed discussion of 

 the effects of wood harvesting on the nutrient cycle of a forest in New 

 Hampshire can be found in chapter 9, "The Forest System." Quantitative data 

 on Maine's forests are unavailable, but the results of the New Hampshire study 

 are generally applicable to coastal Maine. 



The extent to which forest systems are affected by harvesting depends on the 

 care with which logging is carried out. Excessive disturbance of the forest 

 floor and residual understory vegetation by heavy machinery exposes the soil 

 to erosion and thereby delays forest regeneration. Threatened and rare forest 

 plants can be affected severely by clearcutting, especially if site- 

 preparation techniques are employed (i.e., bulldozing, burning, or use of 

 herbicides). Improperly placed roads can stimulate excessive (and avoidable) 

 erosion and cause soil compaction. Cutting too close to streams may cause 

 erosion of banks and exposes stream surfaces to the sun, which increases water 

 temperature. Significant changes in species composition (e.g., fish and 

 insects) in streams as a result of forest clearcutting and agricultural 



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