Although growth exceeds removal of total growing stock, the growth-to-removal 

 ratios of merchantable northern white cedar, northern red oak, white ash, 

 yellow birch, white pine, sugar maple, and beech show over cutting. These 

 trends can be expected to continue because of the increased demand for 

 firewood. Projections of future timber supply show that if present removal 

 trends continue hardwood removals will exceed merchantable growth within 10 

 years, and softwood removals will exceed merchantable growth before the turn 

 of the century. 



Old, mature trees are valuable to the forest system. The Maine State Planning 

 Office is currently evaluating existing stands of mature forests for 

 consideration as critical areas. Preserving mature forests helps perpetuate 

 an entire community of herbaceous species that do not tolerate repeated 

 disturbances, such as lumbering. Although trees are renewable natural 

 resources, replacement of very old trees requires many years, especially under 

 the conditions created by the short rotation (harvest) cycles currently 

 employed by the forest industry. 



Clearcutting often results in the fragmentation of forests. The effects of 

 forest fragmentation on wildlife are not known fully. However, studies of 

 songbirds and mammals have shown that as the size of undisturbed habitats 

 (e.g., forests) decreases (1) the number of species dependent on those 

 habitats decreases, and (2) the number of species using only small areas of 

 those habitats decreases, also. For example, certain songbirds that inhabit 

 forest interiors in New Jersey and Maryland are not found in woodlots smaller 

 than 20 acres (8 ha), even though they may utilize only a few acres. This 

 relationship between species abundance and size of continuous habitat follows 

 island biogeography theory, which predicts that the number of species will 

 decrease as island size decreases or as distance from the mainland (major 

 population pool) increases. In terrestrial habitats on islands, large blocks 

 of continuous natural vegetation are analogous to the mainland. 



Other practices associated with logging or regenerating the forest stands also 

 may affect the system. These include the spraying of herbicides and 

 pesticides and the piling and burning of slash. Herbicides are used in the 

 management of softwood (e.g., spruce-fir ) to kill deciduous trees, shrubs, 

 and herbaceous plants ( e.g., raspberry, cherry, birch, and aspen) that often 

 dominate clearcut sites for many years. These species prevail over the 

 commercially desirable softwood species at early serai stages in much of 

 Maine's forest land, and their dominance delays forest crop rotation. 

 Herbicides similarly affect endangered, threatened, and rare plant species. 

 Selective herbicides are used to kill these "weed" species when adequate 

 softwood regeneration is present or prior to planting softwood seedlings. The 

 long-term effect of removing these plants from regenerating forests is not 

 known. The effect of herbicides on the terrestrial system is discussed 

 further in chapter 9, "The Forest System." 



Herbicides (through direct application and runoff) can affect riverine, 

 palustrine, and lacustrine systems by killing aquatic vegetation, changing 

 local aquatic habitats, and depleting oxygen (through the decomposition of the 

 dead material). Very high doses of herbicides can kill fish. The effects of 

 the relatively low amounts that are used currently by the forest industry are 

 unknown but do not produce observable effects. 



3-6 



