Nice painting mate, beakie with the power axe is my favorite, I guess traditionally spacewolves are based with snow,(going with the whole nordic theme and i guess deep pine forest is hard to show on a 25mm base)
Colour and theme wise I'll leave that up to wiser minds
But you can use dry pastels to base them,(I brought my pack from my local newsagent and use a pencil sharpener and the but of my knife to prepare them(because I'm stingy

) and weather them with the exact same colour and texture material.
(ideal for dry dusty enviroments or similar enviroments after heavy rain)