copying objects to other .blends

is there a way to move something from one .blend to another?
I have a tree in the default Lsystem .blend and a landscape in another can i put the two together and how

thank you for any help

Just hit Shift F1 with your landscape blend open, navigate to the Lsystem blend and go down the list to Object, click on that then pick the mesh in there and open.

you have to append the different objects into your final scene: SHIFT+F1, browse through the blend file as it was a directory, find the objects directory and from there, append the requested object(s).

For more on the topic: tutorial Append.html

hope this helps,