Well, it is kinda funny that the Empire's natural habitat is scorched earth and volcanoes, but kinda cool at the same time.
What I would prefer from total barren wasteland in the "Deadlands" is not a lack of life, but simply a lack of safety. Half the plantlife would be carnivorous (like man eating giant fly traps/ little shop of horrors plants/ Needle grass that drinks blood).
The other half of the plant life would look alien and foreign, like the blood-vine, which draws water, iron, and other resources from the earth. If ever blood is spilled near the vine, it absorbs the blood almost as soon as it could soak into the earth (for the iron). For the same reason (iron), with exposure to oxygen the vine's juices turn blood-red, so if you cut a vine it will almost always "bleed." Another example would be the screaming willow. This willow mainly gets its nutrients from nitrogen rich "bubble bugs" with whom the willow eeks out a symbiotic relationship. The beetles live on the trees surface, and within the tree, while the nitrogen (and other gases) slowly leak into the tree. Due to the high conentration of gases within the tree and beetles, if someone cuts into the willow, the release of compressed gasses will give off a "screaming" sound. As it so happens, many of these Willows' outer bark tends to grow into the shape of a mortified toothy scream.
The creatures, meanwhile, are mostly leftovers from magics long forgotten, and many the result of experiments conducted by the Titans. Some are naturally nightmarish creatures that, given the fitting atmosphere of the Deadlands, while once rare have populated immensely to become regular denizens of the Empire's wilds. As the Fallen re-spread the Deadlands, such creatures come out of the caves and the burrows to once again roam their favored lands.
Tribes and characters you might find within the Deadlands include half-human, wingless Draginoid creatures called Thanelings. Some can breath fire, and some can speak common. All Thanelings, however, can speak Draconian and have raw contempt for outsiders. Fallen are barely welcomed any better than Humans within a Thaneling camp. Usually a tribe of thanelings have a particular dragon that they worship as their central god figure. They of course revere all dragons, but their primary dragon of worship is their patron god even if the Dragon isn't aware of it. Some Dragons, however, find their Thaneling followers amusing and will occasionally give tasks or quests for their thanelings. Some Dragons will ask the Thanelings to protect certain things the Dragon might be interested in, whether it be a cache of treasures or a hidden splendor of nature. The most common interaction between Dragon and Thaneling would be asking a Thaneling to retrieve a treasure that the Dragon is too large to pursue.
Other inhabitants include Demons. Demons are extremely rare, and are as arrogant as they are intelligent. The superior intelligence of a demon allows them to think ahead strategically by 100 steps farther than the average mortal. Because of this, making a deal with a demon is tricky business and more often than not tends to have significant unforeseen consequences, and sometimes even directly backfires onto the client. To find a demon, the best bet would be to search within abandoned castles and dungeons within the deadlands.
Trolls are far from "sentient" and live in Kingdom lands as well, however the larger tribes of trolls tend to live among the deadlands. Their is a cultural unspoken rule between Trolls and Fallen, and they generally tend to leave each other alone unless the Fallen are looking for soldiers. The Krax, on the other hand, often have to work harder to persuade even an individual troll to fight for them.