Use 'File→Export material…' to save the model from the current view as a series of maps intended to be used as texture maps on another tree model. This technique is used largely when making real-time tree models but is also useful for making simple models for background rendering.
The basic idea is to create a model of a small part of the tree that you plan to replicate. Typically, this a section of branches and leaves which will become a leaf texture map on another tree model. The image below shows a model and the corresponding three maps created via 'File→Export material…'.
The leftmost image is that of the tree model itself. The three images on the right of the arrow depict the three maps generated by the tool: diffuse, normal, and specular. Notice that texture streaking is automatically applied to the diffuse and normal maps.
The 'Window' properties have two utilities that work in conjunction with material exporting: