Contents

06 April 2001
Vol 292, Issue 5514

About The Cover

Cover image expansion

COVER A small tundra stream (~5 meters wide) flows between the Brooks Range and Toolik Lake at the Arctic Long-Term Ecological Research site in northern Alaska. Throughout North America, headwater streams such as this actively retain inorganic nitrogen from their watersheds. This retention limits the downstream transport of nitrogen and thereby helps control the eutrophication of downstream lakes and estuaries. See page 86 [Photo: B. J. Peterson]