Making Your Dungeon Ecology Work

Even in video games, one of the biggest problems that dungeon designers face is dealing with the ecology of each dungeon level. Worse, some have problems integrating the individual levels into the dungeon as a whole. There are simple ways that a GM can create a simple ecology and use it to make for better dungeons.

Why You Need an Ecology

Put simply, an "ecology" is how the life forms in a dungeon work together, however clueless of each other's participation in order to create a better living condition for everyone involved. That is, by eliminating the trash, providing what others need to survive, and helping defend the dungeon, each being helps to ensure that the dungeon is a livable environment.

From the perspective of players, creating a working ecology makes the dungeon that much more believable as well as adds to the experience. For players who love small details, it provides the details they need to get lost in the world; it helps build the world up for them and shows that the world has layers. They like it when the world shows some sign of persisting before and beyond them. Video gamers like those details because they love detailed worlds. In both cases, it just adds to the experience of knowing that the world is both lived in and a truly living environment.

What You Need

You're going to need a light source, some plants, some scavengers, some herbivores, and some carnivores. It may be weird to consider plants underground, but unless your dungeon is only a few levels deep you're going to have oxygen issues: Without oxygen, your animals are going to die either due to oxygen deprivation or poisonous gases. In order to have plants, you need light; all you need is a little bio-luminescence and darker leaves. This is why you see ferns so often underground; they don't need much light and the cooler temperatures work for them. You can also use lichens (the algae/fungi hybrid loves the moistness).

This is also why you see so many carnivorous plants underground: They need the extra nutrients and they are used as disposal for some of the more intelligent species. They also provide some solid defensive measures and the firelight from nearby inhabited areas is just enough for them to grow.

If plants underground seem weird, herbivores are even weirder. However, you need them to keep the plants under control; plants break down stone and you need something to slow that down. You may not have huge herbivores, such as cattle or even goats; you need to think smaller. Beetles are just what you need, and they can help pollinate the plants as well. Some of these will even provide a food source for your carnivores if they are big enough.

You should have two levels of scavengers, but three is great. You'll always have microbes, but you may want some insects and oozes to deal with the bigger remains; that takes care of your first two levels. If you have giant creatures, then you're going to need giant scavengers as well; someone needs to deal with the carcasses. If you have large bodies of water, even some decent ponds, you're going to need some crustaceans to deal with those chores. Some of your low-level carnivores will be more than willing to step in and help.

Speaking of the meat-eaters, you should debate another three levels. You're going to need low-level carnivores to make sure your herbivores and scavengers don't get out of control; these are your standard-issue cave spiders, bats, and larger insects and crustaceans. This can also include fish, who do well as herbivores as well. The second level consists of those who feed on them and are your backup scavengers; these are your wolves, hyenas, and even hawks, or just larger versions of what you have already. Definitely don't forget your apex-level predators; just like video game bosses, however, you should only have one or two per level. If you have any more than that, you're going to have problems explaining what they are eating.

And Then It Gets Weird

You should have a decent ecology, but you may want to add some flavor. The first way is to add a creature or plant that breaks the normal rules of physics, such as the undead, electric rats, or something that is the result of magical experimentation. Just decide what it eats and where it fits into the general ecology; you don't want it to overrun the ecology, after all, and even the undead don't eat everything.

The other, and why people are probably there, are the inhabitants. Inhabitants will usually be farmers (raising plants and herbivores), scavengers, or a warrior race using the dungeon as a sort of home (such as your typical goblins and orcs), or even your underground societies. The first two are pretty simple (farmers are just like village farmers (albeit possibly with strange powers) and the scavengers/warriors are just there "temporarily"), but you're going to need to put some serious thought into how the society works.

So there you be. This should allow you to set up a decent ecology. This should also add to the verisimilitude of the setting, giving detail-oriented players the details that they need; if you do it right, even your more combat-oriented players will be very happy with your ecology (they're just there for the bragging rights, such as from killing larger apex predators or really weird creatures). So have fun, be creative, and fill in the niches to your heart's content; this can be more than an exercise in creativity, especially if you have some real fun doing it.