Landscape
 

How do we use this word and when?
is it well used in this sentence " it´s very important because every landscape has a function to regulate the climate like the amazon reinfotest to global warming."
There is sth in this sentence that I don´t like at all. Can anybody improve it?

I think the word you're looking for is "ecosystem".
"Landscape" is just a scenery, un paisaje.

Sometimes landscape is used to mean scenario or hypothetical vision of what is or can be, but as Angela states it usually simply means paisaje.
An example of landscape as scenario is the following: Terrorist attacks are designed to create a landscape of panic throughout a nation.

Could be "panorama" instead of "paisaje" in this example?

To be honest, I think that is an abuse of the word, not use. A landscape is a picture depicting inland scenery. It is used elsewhere when somebody can't think of a better word.

Now you're creating a different landscape altogether;)
I too prefer the paintings Heade or Bierstadt over a historian's or political analyst's interpretive landscapes.

Pinosolana,
I think panorama which usually means a wide vista can also mean scenario. Example: the panorama changed when the shah was toppled and....

+1 for "ecosystem"

A better sentence (in my opinion):
"It´s very important because every ecosystem has a function to regulate the climate such as the Amazon Rain Forest with global warming."

Yes, I think so. "Paisaje" wouldn't work for this, but "los ataques terroristas están hechos para crear un panorama de terror en todo el país" would sound a little too media-like to me, but it would be expressive enough. :)