Thanks!
@Foxley: I spent some time browsing through the google image results for "
snow covered pine sapling" before I started on the small pine trees. It helped immensely.
@kylekrack: Here is a gif showing the ramp I used. I only used a 3-color ramp. More would have been overkill. Notice that I mixed two different brown ramps. That is a (very simple) example for the cross-ramp stuff that 0ion9 and TMC were talking about in the palette thread. Mixing your own ramps out of colors from different but similar ramps can produce good results
Specifically for tree trunks, I like browns that lean towards grey or white, and avoid browns that lean towards red (unless it is supposed to be a cedar, or a manzanita, or something that is *supposed* to be very red)