How do I treat raw pine wood?

I am using the trunk of last year's christmas tree as a stand for a dress form. I cut all the branches off but I'm not sure what to do next. I want it to look relatively organic, (not drastically sanded down or anything), because i like the raw naturey look, but I also don't want it to quickly rot and I don't want it to feel sticky from sap residue. What kind of oil or varnish can I use on it to treat it? Thanks so much