Kimberly Howlett, age 8, of Gallup, N.M., for her question:

WHAT EXACTLY IS THE TUNDRA?

The tundra lands belong to the Arctic, where the winters are long and cold, long enough to freeze the ground solid way down deep below the surface. The summers are short and quite warm, but not warm enough to thaw the ground more than a few inches, or perhaps a foot deep. The key to life on the tundra is the fact that the ground just below the surface is frozen solid throughout the year.

This makes it impossible for trees to set down deep roots  and explains why the tundra is treeless. However, there are lots of low growing plants that burst into bloom during the short summer season. Many have only 40 days to grow, blossom and produce seeds. Zillions of insects come to life during the short summer and the season is just fine for flocks of birds who arrive to build their nests.