In general, they prefer a mix of low and medium-height vegetation with some trees, and avoid dense forests as well as treeless arid regions.

In this treeless region, hundreds of species of grass, wildflower, moss and lichen are found.

Dried manure (usually known as dung) of cows was, and still is, an important fuel source in countries such as India, while camel dung may be used in treeless regions such as deserts.

Tundra is the cold, treeless region around the poles that has permafrost as one of its defining features.

These blues have colonized the treeless alpine region, at a higher altitude than the habitats of their parents, said Zachariah Gompert, a graduate student in biology at Texas State and principal author of the group's paper, published in the Nov. 30 online edition of Science.

On isolated mountains, montane forests surrounded by treeless dry regions are typical "sky island" ecosystems.

It is, however, absent in the relatively treeless regions of the Great Plains and the northern coasts, which are outside the natural range of the snowshoe hare.

Many raptors, such as falcons and sparrow hawks, the American counterpart of the kestrel, are believed to have ultraviolet vision and, in treeless regions, this could be an aid to hunting.

In almost treeless regions it is used as firewood.