From The Free Dictionary:
A vast semiarid grass-covered plain, as found in southeast Europe, Siberia, and central North America.
I wanted to do this word because, quite frankly, though I have had a number of ecology classes over the years, I never really felt like I grasped the meaning. Numerous sources, including wikipedia, have mentioned that a steppe is a place with a climate that is too dry for a forest, but not quite dry enough to qualify as a desert and therefore the plant life it supports is usually in the form or grasses or shrubs. A similar concept, tundra is also unable to support trees but in this case the dryness results because the ground is permanently frozen (this is known as permafrost).
I became interested in steppe ecology after seeing some very interesting documentaries about Mongolian nomads and their amazing horses. These people have an amazing way of life and despite the fact that they are nomadic they seem to be surprisingly wealthy. If you get a chance, watch a little bit of this video from National Geographic.