It's easy to animate your trees. In this example, we'll make the tree bend in the wind.

First, create a tree (any kind) by dragging it from the tool palette in the usual way.

Next, Move the sequencer arrow to the 1 second mark...

...and in the Model room, change the wind slider to 60%.

Move the sequencer arrow to 2 seconds, and put the wind slider back to zero percent.

Finally, render the movie, and save it. The result is the image at the top of this page. You've created and animated the wind!

The same technique demonstrated above can be used to animate gravity, sunlight, or any other parameter in the Tree Druid dialog box. You can even animate several of the tree parameters at the same time!