Region
Africa
6
Alaska
5
Alaska, Southeast
1
Amazon River Region
2
America
1
Amsterdam
1
Angelina River Valley
2
Angelina River Valley (Tex.)
2
Antarctica
2
Appalachian Region
1
Arctic National Wildlife Refuge (Alaska)
1
Arctic regions
3
Arizona
1
Arusha National Park
1
Arusha National Park (Tanzania)
1
Asia
1
Assisi
1
Atlantic Coast
1
Australia
21
Australia, Southeastern
1
Baringo District
1
Baringo District (Kenya)
1
Berlin
2
Booderee National Park (A.C.T.)
1
British Columbia
1
California
9
California, Gulf of
1
Canada
4
Canada, Eastern
1
Caribbean Area
1
Cerro Azul Region
1
Cerro Azul Site (Peru)
1
China
2
Cold regions
1
Colorado
1
Columbia River Watershed
1
Costa Rica
4
Côte d'Ivoire
2
Darling River Watershed (Qld. and N.S.W.)
2
Developing countries
1
Earth (Planet)
1
East (U.S.)
3
Easter Island
1
England
2
Europe
6
Europe, Central
1
Flint River
1
France
1
Georgia
1
Germany
2
more ...