While we're on the subject of ecology and iconic epics, Frank Herbert's Dune - see the official Dune website - was probably the first work that made a genuine effort to construct a coherent ecological model. The desert planet Arrakis presents a highly complex ecology where a limited Earth-style biosystem (for which free water is vital) is in a precarious coexistence with an alien biosystem (to which water is largely fatal) which must be maintained as it produces "spice", an addictive drug critical to interstellar transportation.
While I think the central concept has been over-stretched by far too many sequels and spinoffs, the original Dune novel has stood the test of time, and works at many levels. There are various resonances with the historical and present Middle East. The "spice" (without which transportation would collapse) could be viewed an allegory for petroleum; and many of the situations and factions resemble historical ones, such as the fall of the Roman and Ottoman Empires, with their respective Praetorian Guard and Janissaries. The story of Paul Atreides, an outsider who joins and leads the Fremen in driving out an occupying army, has more than a passing resemblance to that of Lawrence of Arabia.
An interesting discussion at Language Log - Munroe's Law, concerning neologisms in novels - reminded me also of Arabic and Islamic themes in Frank Herbert's "Dune", which explains the terminology in Dune. For instance, the name for the Messiah-like "Kwisatz Haderach" comes from the Hebrew Kefitzat Haderech - literally, "shortening of the way" or "jumping of the path/road/way" - which refers to teleportation in Jewish folklore, an ability with various analogues including the Muslim Tay al-Ard ("folding up of the earth") and the Sufi Tay al-makan ("folding space" - exactly the term used within the Dune mythos for the mechanism of interstellar transportation.
I've seen both movie adaptations. Personally I like the 1984 David Lynch one a lot; it's memorable and visually stunning. And yet I think David Lynch's Dune: What Went Wrong? (Joshua Moss, Starport.com, 5 December 2000) summarises very fairly the problems: huge areas of complexity were dropped, and the Harkonnens were made into cartoon abominations. Furthermore, it completely lost a central point to Dune; as Herbert has repeatedly stated (as in Dune Genesis, Omni Magazine, July 1980) the intended message wasn't a simple good vs evil, but that visionaries are not be trusted: "Don't give over all of your critical faculties to people in power, no matter how admirable those people may appear to be". The 2000 miniseries, Frank Herbert's Dune, although it makes its own departures from the text and I think it's less striking in visual design, is rather more faithful to the spirit of the book.
P.S. Another thing Dune has in common with The Lord of the Rings
is having a not-very-good National Lampoon parody. I do rather like, though, the Dune redub at the movie parody site Sequential Pictures ("It's always fun to urbanize the ludicrous glossary that Herbert created. Is Dune the best movie of all time? Absolutely not. Is there a guilty pleasure in liking it? Perhaps").