The Martian Terraforming Research habitat is a terrarium in both name and type. The interior has been carefully fine-tuned to match temperate-zone martian conditions once terraforming has completed and stabilized, and seeded with desirable plants and animals. In the time to come, the ecosystem will be allowed to evolve to suit the conditions of terraformed Mars, with some guidance in the form of genetic engineering.
The trees grow massive in the light gravity, becoming ecosystems themselves, like the largest trees on Earth. Goat-like, long-limbed "rust deer" leap great distances and climb unintuitively well, when not resting to store oxygen. Great gliding eagles pluck resource efficient monkey-sloths from the great trees. This is Mars as it will be.
Plot Hook: Terraforming has been opposed by most barsoomians, wishing to maintain their ways of life on a cold, dry Mars, although some would welcome a livable wilderness. As an @-rep favor, a player is asked to help design a pathogen to attack the martian ecosystem. As a high @-rep favor, a player is asked to participate in the introduction of the pathogen.