Here is one example: Sarah Moon's Light Comes interweaves themes of mountaintop removal, the invention of the lightbulb, and the sacredness of earth.
See this script excerpt. Others of her Moon Plays show strong influences from Berthold Brecht's agitprop and Augusto Boal's "theatre of the oppressed" inspired by Paulo Freire. Boal has also influenced Montreal's Engrenage Noir.
The "environmental theatre" of natural or found settings was explored by Richard Schechner's Performance Group in New York, and in his book Environmental Theater (1994). See discussions in Helium.com and Wikipedia on site-specific theatre. Some recent examples are Times Up, the Church of Earthalujah (formerly Church of Stop Shopping), and New York Loves Mountains.
Eco-theatre draws on many other traditions: Butoh, Kabuki's hanamichi, Christian miracle plays, Hindu Ramlila, the Black Mountain festivals, happenings, Jerzy Grotowski, Jacques Lecoq and Ariane Mnouchkine, Tadeusz Kantor, Vselovod Meyerhold, Nikolai Okhlopkov, Eugenio Barba, Dario Fo, Peter Schumann's Bread and Puppet Theater, En Garde Arts, Forced Entertainment, James Slowiak and Jairo Cuesta's New World Performance Laboratory (NWPL), Mike Lawler's eco-theater, Jeff Burroughs' 9Thirty Theater, Restless Natives in Totnes, England (see their website and its links), Climate Change North, Confluence Theatre Co's (re)CYCLE plays, and numerous plans for greening theatre buildings. Dancer Tevyn East has created an eco-liturgy of movement and questions, Affording Hope.
Therapeutic theater and dance has blazed its own trails. A landmark is choreographer Bill T. Jones' moving, musical, marvellous Still/Here (1994) with real people facing life-threatening illnesses; a 60 min video/DVD shot in 1997 is available; see this online excerpt from Bill Moyers' PBS program. Some other notable artists in this genre are: Margie Gillis -- especially her M.Body.7 (2008) for dancers ranging in age from 12 to 73; Vida Simon; Petra Kuppers; Epiphany Productions in San Francisco -- see its video Fears of Your Life (2007); a group in a Calcutta jail; and many groups in Boston -- see also the Lesley University dance therapy website and its links.