Chapter 9 



The Forest System 



Author: Craig Ferris 



Forests, the major terrestrial habitat in Maine, comprise about 857o of the 

 coastal land area (table 9-1). They largely determine the characteristics of 

 the hydrology, microclimate, soil structure, nutrient flow, and animal 

 composition of the terrestrial habitats of coastal Maine. 



In ecological terms forests are systems. They are somewhat independent of 

 other ecosystems but require sufficient nutrients and minerals from the soil, 

 nutrient inputs from precipitation and the atmosphere, and energy from the 

 sun. Mature forests have a large standing biomass of plant tissue, extensive 

 root systems and a large photosynthetic surface area. Forests are among the 

 most productive terrestrial habitats and support numerous and diverse forms of 

 animal life, including insects and other invertebrates, reptiles (snakes), 

 amphibians (frogs, toads, and salamanders), birds, and mammals. In spite of 

 the abundance of above-ground animal life, nearly all of the annual production 

 of plant material in forest systems falls to the forest floor where it becomes 

 the source of energy for a complex detritus-based food web. 



Although forests tend to be independent of other ecosystems their output 

 sometimes strongly influences other systems. The nutrients transported out of 

 forest systems in surface and underground runoff represent very small amounts 

 of the annual productivity. Although this loss is insignificant to the forest 

 system it may form the primary energy source for streams that receive runoff 

 from forest land. Forest vegetation also moderates the flow of water out of 

 forest systems, reducing the peak flows in streams. Herbicides or pesticides 

 applied to a forest and carried in the runoff could pollute the streams. 



Major disturbances or perturbations to forest systems include fire, logging, 

 wind storms, and insect dama^^e. Normally forests recover rather quickly from 

 these perturbations, because regrowth of herbaceous and woody vegetation and 

 trees usually repopulate the area within a year or two. After 40 to 60 years 

 a disturbed area may support a mature forest. On the other hand, excessive 

 disturbance resulting from severe fire or careless forestry practices may 

 result in erosion of both organic matter and mineral soil, which exposes 

 infertile soils on which forest recovery is slow. 



9-1 



10-80 



