What is an ecosystem?
Ecosystem is the interaction of the community of plants, animals and the environment of an area. This can be:
•	Intact, as the environments aeolian to the limits of the Alpi 
•	Modified by the man, woods and pastures of high height . They are modified following human intervention but they can also last him without his intervention. 
•	Held up by the man, they are the countries and the cities, that remain what we see them to us thanks to the continuous human intervention.
In an area they coexist to various staircases different ecosystems, they are as ecosystems so much a rotten stump a slope wood.
What is a wood?
The wood is an ecosystem modified by the man characterized by presence of arboreal individuals that cover a remarkable part of the ground.To speak of a wood, with all the wealth of relationships among the various components of the ecosystem, it is therefore necessary there is a least surface of formation.
What is a forest?
The forest is an ecosystem who was born from interaction of many ecosystems that insist in a big area where woods are dominant.Within the forest we can find freshwater ecosystem, pasture, clearing, peat bog and other environments.

Why are there many interest for woods?
Because man has got many expecations in confrontation of woods and their coexistence isn't always easy and possible. So in many situations operation of man is necessary to realize these waits called functions of the wood.
Forestry is intervents possible in a wood.
Settlement and organisation of space an in time of intevents in forestry is a compromise between perception of the human time and perception of the wood.

What are the function of woods?
Productive, like the production of timber but in other area also mushrooms and little fruits.
Protective, they protecte the stability of a slope, of a source, or of the same wood if formation is instable that an intervent compromise the stabililty.
They have got tourist-recreational function for a direct fruition by people and for overview that makes agreeable a valley.
Naturally and environment for a determined species of interest or for an ecosystem that deserve protection; or fixation of carbon dioxide.
Hygienic-sanitary, for example a park near city that improves qualty of the air anf of the life.

Why do we speak about different kinds of woods?
To value what practise of forestry we should realize to maximize functionality is necessary a comparison and a a discussion.
The limit of the human mind can compare itself with other people in something if it gives some names, subdivides naturally variety in groups more or less homogeneus.
So it happens for plants and animals, as study and speak about it without to group them and give them names.