Can we Bake 2 Textures into 1 to Map the same Objects?

I make trees in Xfrog. Lately I been making game assets which requires only 1 texture map. I usually import the trees into Blender and Unwrap each part to map with an image using both bark and leaf images. It’s very tedious. I was wondering if there’s an easier way to do this. Is it possible to bake the 2 images from the tree and somehow apply the new texture that have both images combined back onto the tree automatically?