Bonny Portmore - a early lament about losing trees (well OK, one tree).
I believe Rise Up Singing has a section on ecology - don't have it handy but I'm sure someone does and could list the titles int hat section.
And then there's always the play list from the No Nukes concert - again, I don't have it handy (darn, why don't I keep my music collection here at work?) I'm sure someone else here at Mudcat has the vinyl or CD.