for further detail i put scrap pieces on the base, doesn't matter what i looks like, could be anything, fallen trees, stones, growth of chaotic moss, just paint accordingly.
for further detail,if you score the dowels deeply you can add the smallest dowels you have to the trees to make branches, however these break and get in the way of models. the smallest i think you can get are 1/32. so if you add these be prepared to lose some. also if you are really brave use a torn up coffee filter to act as leaves you can either tear into small chunks to put on branches or you can use it like an umbrella cover and just drape it over the main body of your tree. these additions add a lot of time, and probably wont look great the first time you do it, but the more you do the better they get as you learn from mistakes
this process takes little time, if you want to paint go for it, but it eats up citadel paint, and the more detail you add the less you want to paint. i would say each base of trees took an hour to two to make and maybe another two to paint. these are just table top pieces, not supposed to be showcase elements, but they are better than paper forests.
all this is really cheap, 5 dollars of materials if that, at start buying tools is expensive but once you have them no need to spend, i suggest an exacto knife, some wooden dowel cutters, a metal ruler and a cutting board and of course glue, elmers works just fine.